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For medicinal purposes, the herb and flowers of meadowsweet are used. The leaves, flowers and roots of meadowsweet contain flavonoids, phytoncides, steroids, terpenes, glycosides, tannins, starch, essential oil, vanillin, and, most importantly, in large quantities, vitamin C. The grass of meadowsweet contains 0.2% essential oil ( the components of which are methyl salicylate and its bioside gaulterin, salicylic aldehyde, vanillin), phenolic glycosides (monotroposide, primverozide, salicin, spirein), flavonoids (4%: avicularin, hyperoside, spireoside), tannins - 15%, coumarins, steroids , vitamin C, trace elements.
Let us consider in more detail the action and properties of chemical compounds of meadowsweet.
Vitamin C. Participates in the biosynthesis of corticosteroid hormones, which are responsible for the adaptive reactions of the body; enhances immunity; eliminates inflammation; stabilizing effect on connective tissue; improves the psycho-emotional state, since it affects the formation of dopamine, norepinephrine, as well as serotonin and endorphins.
Tannins. These substances precipitate protoplasmic proteins, thereby exerting either an irritating or an astringent effect on the mucous membranes (it all depends on the concentration of the solution). Properties: astringent; hemostatic; antioxidant.
Phenolic compounds (monotropitin, spirein). Properties: stimulating (activates the functioning of the adrenal cortex); antiseptic; diuretic; adaptogenic (increase the body's defenses); antispasmodic; sedative; choleretic; hemostatic.
Salicylic acid... Action: normalizes capillary permeability, thereby preventing tissue edema; participates in the formation of inflammatory mediators; stops the biosynthesis of prostaglandins, which play an important role in the development of inflammation, as well as pain, which relieves inflammation.
Figure 5.1 - Salicylic acid
Flavonoids: avicularin. Properties: anti-inflammatory; antiallergic; antivirus; anticarcinogenic; antioxidant; choleretic; antiulcer; diuretic; antispasmodic.
Figure 5.2 - Avicularin
Catechins... These substances neutralize free radicals, thereby preventing the development of cancer. In addition, catechins resist the effects of bacteria and prevent cell destruction, thereby significantly slowing down the aging process of the body.
Phenol carboxylic acids. Action: relieve inflammation; accelerate the process of excretion of bile; enhance kidney function; stimulate the antitoxic function of the liver.
Essential oils. Components: methyl salicylate and salicin. The action of essential oils: normalizes the functioning of the cardiovascular system; soften cough; increase the separation of mucus from the bronchi; improve the work of the digestive tract. Properties: bactericidal; anti-inflammatory; antiseptic; stimulating; sedative.
Figure 5.3 - Methyl salicylate Figure 5.4 - Salicin
Fatty acid... The action of fatty acids: participate in the formation of energy; participate in the construction of membranes that make up the skeleton of cells; normalize metabolism, being components of various lipids.
Glycosides. Properties: diuretic; antimicrobial; sedative; laxative; expectorant; vasodilator; disinfectant. Starch. It is used as an enveloping agent in the treatment of inflammatory diseases of the gastrointestinal tract. In addition, starch belongs to the class of easily digestible carbohydrates, which, being transformed into glucose, quickly saturate the body with energy.
Figure 5.5 - Starch
Wax. Possesses bactericidal and astringent properties, therefore it is used in the treatment of difficult healing wounds and various skin diseases.
In 1828, the Munich pharmacist Johann Büchner isolated the anti-inflammatory substance salicin from the willow bark, the hydrolysis of which yielded salicylic acid, and in 1838 the Italian chemist R. Piria isolated spiraeic acid from the meadowsweet (spirea), which turned out to be a derivative of salicylic acid. It turned out that there is a lot of salicylic acid in willow meadowsweet - Spiraea salicifolia, and then Felix Hofmann, an employee of the German company "Bayer", developed a technology for the organic synthesis of acetylsalicylic acid, which received the commercial name "aspirin". This name is made up of two parts: "a" from acetyl and "spir" from Spiraea. In meadowsweet aspirin is in glycosylated form. Quite recently, diterpene alkaloids, called spiramins and spiratins, were isolated from the seeds and roots of meadowsweet. Their action is similar to camphor, caffeine, but the use does not cause an increase in blood pressure. According to scientists, spiramins protect brain cells from oxygen starvation. Anti-clotting agents have been isolated from Japanese meadowsweet.
The tannins of meadowsweet, undergoing oxidation, turn into substances with a bloody color - flobaphenes .
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MEDICINAL PLANTS AND RAW MATERIALS CONTAINING PHENOLIC COMPOUNDS (general characteristics).
The concept of phenolic compounds, distribution in the plant kingdom.
The role of phenolic compounds for plant life.
Classification of phenolic compounds.
Biosynthesis of phenolic compounds.
The concept of phenolic compounds, distribution in the plant world, the role of phenolic compounds for the life of plants.
Plants are capable of synthesizing and accumulating a huge amount of phenolic compounds.
Phenols are aromatic compounds containing in their molecule a benzene ring with one or more hydroxyl groups.
Compounds containing multiple aromatic rings with one or more hydroxyl groups are called polyphenols.
They are found in various parts of many plants - in the integumentary tissues in fruits, seedlings, leaves, flowers and
Pigments of phenolic nature - anthocyanins - give them color and aroma;
most polyphenols -
Active metabolites of cell metabolism,
play an important role in various physiological processes, such as photosynthesis, respiration, growth, plant resistance to infectious diseases, growth and reproduction;
protect plants from pathogenic microorganisms and fungal diseases.
Spreading.
Of phenolic acids, gallic acid is often found and salicylic acid (tricolor violet) is much less common. Phenolic acids and their glycosides are found in Rhodiola rosea.
To the group of phenols with one aromatic ring relate simple phenols, phenolic acids, phenol alcohols, hydroxycinnamic acids.
Phenologlycosides is a group of glycosides, the aglycone of which are simple phenols that have a disinfectant effect on the respiratory tract, kidneys and urinary tract.
Phenologlycosides are widespread in nature. They are found in the families of willow, lingonberry, saxifrage, tolstyanka, etc., are found in the leaves of bearberry and lingonberry.
Natural phenols often exhibit high biological activity:
Preparations based on phenolic compounds are widely used as
Antimicrobial, anti-inflammatory, hemostatic, choleretic, diuretic, antihypertensive, tonic, astringent and laxative.
Phenolic compounds have a universal distribution in the plant kingdom. They are characteristic of every plant and even every plant cell. Currently, over two thousand natural phenolic compounds are known. Substances of this group account for up to 2-3% of the mass of organic matter in plants, and in some cases - up to 10% or more. Phenolic compounds are found in both the lower ones; mushrooms, mosses, lichens, algae, and in higher spore (ferns, horsetails) and flowering plants. In higher plants - in leaves, flowers, fruits, underground organs.
The synthesis of phenolic compounds occurs only in plants, animals consume phenolic compounds in a ready-made form and can only transform them
In plants, phenolic compounds play important role.
1. They are obligatory participants in all metabolic processes: respiration, photosynthesis, glycolysis, phosphorylation.
Research of the Russian scientist biochemist VI Palladin (1912) established and confirmed by modern research that phenolic compounds are "respiratory chromogens", ie. they participate in the process of cellular respiration. Phenolic compounds act as hydrogen carriers at the final stages of the respiration process, and then they are again oxidized by specific enzymes, oxidases.
2. Phenolic compounds are regulators of plant growth, development, and reproduction. At the same time, they have both a stimulating and an inhibitory (slowing down) effect.
3. Phenolic compounds are used by plants as an energetic material, perform structural, support and protective functions (increases plant resistance to fungal diseases, have antibiotic and antiviral effects).
Classification of phenolic compounds.
The classification of natural phenolic compounds is based on the biogenetic principle. In accordance with modern concepts of biosynthesis and, based on the structural features of the carbon skeleton, all phenols can be divided into 8 groups:
1. From 6 - row -
simple phenols with one aromatic ring, one or more OHgr.
2.C 6 -C 1 -series-phenolcarboxylic acids
З. С 6 -С 2 - rows -
Phenolic alcohols
n-thirazole
8. (С 6 - С 3 - С 6) n - Phenolic compounds 4. С 6 - С 3 - derivatives
polyphenolic phenylpropane - oxycinnamic
With 
compounds of acids, coumarins, chromones
tannins
7.С 6 - С 2 - С 6 - 6. С 6 - С 3 - С 3 - С 6 - 5. С 6 - С 3 - С 6 - rows
row - quinones, row - lignans flavonoids
derivatives
anthracene
Biosynthesis of phenolic compounds.
Biosynthesis in various groups of phenolic compounds proceeds according to the same principled scheme, from common predecessors and through similar.intermediate products.
All phenolic compounds in plants are formed from carbohydrates (acetate-malonate pathway) and the products of their conversion, and in the process of biosynthesis pass the shikimate pathway.
The biosynthesis of many phenolic compounds is preceded by the formation of amino acids - L-phenylalanine and L-tyrosine.
Phenolic compounds are formed in three ways, the first two and third paths are mixed (separate parts of the same compound are synthesized in different ways).
Acetate-malonate pathway.
Installed by American scientists Birch and Donovan in 1955. The precursor is acetic acid, which is formed from sugars.
As a result of the stepwise condensation of acetic acid residues, polyketomethylene acids are formed. The attachment occurs according to the "head" - "tail" type with the obligatory participation of the enzyme Coenzyme A with the intermediate formation of acetyl-Coenzyme A, and then malonyl-Coenzyme, and therefore is called the acetate-malonate pathway). The cyclization of polyketones occurs under the action of the synthetase enzyme.
Biosynthesis scheme:
acetic acid polyketomethylene acid
C 2 -C 6 - H 2 O
phloroglucinol nucleus methyl salicylic acid
If the chain is extended to 16 carbon atoms (8 residues of acetic acid), an anthracene nucleus is formed.
The biosynthesis of simple phenols and anthracene derivatives in fungi and lichens proceeds along the acetate-malonate pathway; anthraquinones of the chrysacin group of rings A and C; anthraquinones of the alizarin group in higher plants; rings In the flavonoid molecule, gossypol, found in the bark of cotton roots.
Shikimate path.
Biosynthesis through shikimic acid, a compound close to aromatic compounds. In deciphering this biosynthesis pathway, a large role belongs to the scientist B. Davis (1951-55).
The initial products of biosynthesis are phosphoenolpyruvate and erythrose-4-phosphate, formed in the process of glycolysis and the pentose cycle of sugars. As a result of a number of enzymatic reactions and condensation, shikimic acid is formed from them.
Further, in the process of successive enzymatic reactions proceeding with the participation of ATP, another phosphoenolpyruvate, the number of double bonds increases to two - prefenic acid is formed, then up to three - phenylpyruvic acid or hydroxyphenylpyruvic acid is formed. Further, under the influence of enzymes, aromatic amino acids are formed - phenylalanine and tyrosine.
With the participation of ammonia lyase enzymes, ammonia is cleaved from amino acids and, respectively, cinnamic and p-hydroxycinnamic acids arise.
Biosynthesis scheme:
SHIKIMAT WAY OF BIOSYNTHESIS AROMATIC AMINO ACIDS (1)
phospho-erythroso-7-phospho-3-deoxy-3-dehydroquineenol-4-phosphate D-arabino-heptulo acid-pyruvate zonic acid
SHIKIMAT WAY OF BIOSYNTHESIS AROMATIC AMINO ACIDS (2)
These are the initial products of the synthesis of p- and o phenols in higher plants, coumarins, chromones, lignans, ring B in the flavonoid molecule, ring B of anthraquinones of the alizarin group in higher plants, hydrolyzable tannins.
Mixed way
A mixed pathway synthesizes flavonoids and anthraquinones, alizarin derivatives. Flavonoids are the source of the synthesis of condensed tannins.
Phenol glycosides (simple phenol glycosides)
1. The concept of phenologlycosides.
2. Classification of simple phenolic compounds.
3. Biosynthesis, localization, influence of environmental conditions on the accumulation of simple phenolic compounds.
4. Physical and chemical properties.
5. Methods for the analysis of raw materials containing simple phenolic compounds.
6. Raw material base of medicinal plants.
7. Features of collection, drying and storage of raw materials.
8. Ways of use and application in medicine of raw materials and preparations containing simple phenols.
Phenologlycosides are a group of glycosides, the aglycones of which are simple phenols, which, upon hydrolysis, are cleaved into aglycones containing one or more hydroxyl phenolic groups on one benzene ring and sugar, which is linked through a hydroxyl and has a disinfecting effect on the respiratory tract, kidneys and urinary tract.
In addition to phenolic hydroxyls, oxymethyl, oxyethyl, or carboxyl groups can be used as substituents in aglycones.
Most often, phenols are in a bound form, in the form of glycosides or esters, but they can be structural units of more complex compounds, such as flavonoids, lignans, tannins.
Phenologlycosides are widespread in nature. They are found in the families of willow, lingonberry, saxifrage, tolstyanka, bearberry and lingonberry leaves.
The simplest are phenyl-O-glycosides.
Classification.
Depending on the nature of the substituents in the benzene ring, phenolic glycosides can be divided into 3 groups:
1st group: From 6 - row
1) monohydric phenols
simple phenols (monophenols) - monohydroxy derivatives - are rarely found in plants.
phenol
Phenol itself is found in the needles and cones of Pinus silvestris, essential oils of the leaves of Nicotiana tabacum, Ribes nigrum, and lichens.
2) Dihydroxy derivatives - diatomic phenols (diphenols)
a) Pyrocatechol (1,2-dioxybenzene) found in ephedra leaves, onion scales, grapefruit.
b) Of the dioxybenzenes, the most common hydroquinone (1,4-dioxybenzene).
Its glycoside is arbutin, which is contained in representatives of the families: Ericaceae (bearberry leaves), Vacciniaceae (lingonberries), Saxifragaceae (badana).
Along with arbutin, these plants contain methylarbutin.
Its aglycon is methylhydroquinone
Arbutin methylarbutin
v) Resorcinol (1,3-dioxybenzene) (or m-dioxybenzene) found in various natural resins, tannins.
Triatomic phenols (triphenols).
The representative of trioxybenzenes is phloroglucinol (1,3,5-trioxybenzene), in free form, it is found in sequoia cones and onion scales, and in the form of florin glycoside - in the pericarp of fruits of various citrus species.
More complex compounds are phloroglucides (phloroglucinol glycosides), they can contain one phloroglucinol ring (aspidinol) or are dimers or trimers (flavaspidic and philicic acids).
Significant amounts of phloroglucides accumulate in the rhizomes of the male fern.
aspidinol
Group 2:
1) C 6 - C 1 - row - Phenol carboxylic acids
Phenolic acids are widespread in plants, but are not the main biologically active substances in them; these are typical accompanying substances involved in the therapeutic effect of total preparations.
Widespread in plants of the families: legumes, sumac, violet, lingonberry.
Widespread n-hydroxybenzoic acid
For instance, pyrocatechic acid characteristic of angiosperms.
Gallic acid maybe
accumulate in significant quantities (in bearberry leaves)
Salicylic acid is relatively rare, the salicylic acid glycoside aglycone contains a carboxyl group:
Its methyl esters are part of the essential oils of plants of the families of violet, birch, willow (field violet grass, raspberries, has anti-inflammatory and antipyretic effects).
3. C 6 - C 2 - rows - Phenolic alcohols and their glycosides are contained in Rhodiola rosea
Salidroside and salicin.
The aglycones of these glycosides are 4-hydroxyphenylethanol and 2-hydroxyphenylmethanol (salicylic alcohol). Along with phenolic hydroxyls, these aglycones have alcoholic hydroxyl groups, and their glycosidation can be based on phenolic and alcohol groups:
Salicylic alcohol
Salicin Salidroside
(2-hydroxyphenylmethanol)
Salicin was obtained from willow bark by the French scientist Leroux in 1828. There is a lot of it in the leaves and shoots of bearberry, lingonberry, pear, bergenia. It is often accompanied by methylarbutin in plants. Salidroside was first isolated in 1926 from willow bark, and later found in the underground organs of Rhodiola rosea.
C 6 - C 3 - row - hydroxycinnamic acids
The most common caffeic acid and its compounds:
Cinnamic acid n-coumaric acid caffeic acid 
Rosemary to-that chlorogenic to-that
Chlorogenic acid is found in green coffee beans (6%), tobacco leaves (8%); Rosmarinic acid was first found in medicinal rosemary, but it is also found in other representatives of the labiate.
The precursor of oxycinnamic acids is phenylalanine.
Hydroxycinnamic acids have antimicrobial and antifungal activity and exhibit antibiotic properties. Hydroxycinnamic acids and their esters have a targeted effect on the function of the kidneys, liver, and urinary tract. Contained in the herb of field horsetail, St. John's wort, tansy flowers, sandy immortelle.
Physicochemical characteristics.
Phenolic glycosides isolated in pure form are white crystalline substances with a certain melting point, soluble in water, ethanol, insoluble in ether and chloroform.
All phenolic glycosides are optically active due to the presence of a carbohydrate component (usually glucose) in their molecule.
Phenolic glycosides, like all O-glycosides, are characterized by the ability to hydrolyze when heated with mineral acids or when thermostated with enzymes.
During hydrolysis, cleavage occurs to the carbohydrate component and the corresponding aglycone. Aglycones are insoluble in water, but readily soluble in ether, chloroform, ethyl acetate.
Simple phenols have characteristic UV and visible absorption spectra.
Phenolcarboxylic acids are crystalline substances soluble in alcohol, ethyl acetate, ether, aqueous solutions of sodium bicarbonate and sodium acetate.
The chemical properties of simple phenols are due to the presence of:
aromatic ring
phenolic hydroxyl
carboxyl group
glycosidic bonds.
Phenolic compounds are characterized by chemical reactions:
Undergo hydrolysis reactions (due to glycosidic bonds) with acids, alkalis, enzymes.
Phenolic glycosides are easily oxidized, especially in an alkaline medium (even with atmospheric oxygen) to form compounds of the quinoid structure.
Phenolic compounds, possessing acidic properties, form water-soluble phenolates with alkalis.
They form colored complex compounds with metal ions (Fe, Pb, Al, Mo, Cu, Ni).
They enter into azo coupling reactions with diazonium salts, forming azo dyes from orange to cherry red.
Phenol carboxylic acids form esters (depsides).
Biosynthesis, localization and influence of environmental conditions on
accumulation of simple phenolic compounds.
The biosynthesis of simple phenols in higher plants follows the shikimate path.
Phenolic compounds are localized both in the aerial part (leaves and shoots of bearberry and lingonberry , and in underground organs (rhizomes of the male fern, rhizomes and roots of Rhodiola rosea, bark of cotton roots).
During the period of budding and flowering, aglycone hydroquinone accumulates in the raw materials of bearberry and lingonberry, which, when dried, undergoes oxidation to quinones - dark pigments, therefore, the raw materials harvested during the flowering period turn black.
The glycoside arbutin is formed in the fall during fruiting and in the spring before flowering. At the same time, the maximum accumulation of salidroside glycoside in the raw material of Rhodiola rosea, phloroglucides in fern rhizomes, gossypol in the bark of cotton roots.
The accumulation of simple phenols and their glycosides occurs in temperate and cold climates in plants growing in forest and tundra zones.
Selection and identification methods.
Phenolic glycosides are extracted from plant material with ethyl and methyl alcohols (96, 70 and 40 0), then purification is carried out.
Isolation of individual compounds is carried out, as a rule, by the method of adsorption chromatography on polyamide, silica gel, cellulose.
Water and aqueous alcohol are used as eluting mixtures, if the adsorbent is polyamide or cellulose, or various mixtures of organic solvents.
Phenolic glycosides in medicinal plant raw materials can be identified by chromatography in a thin layer of sorbent or on paper. When treated with specific reagents and scanning in UV light, they appear as colored spots with corresponding values Rf. For example, the main component of the underground organs of Rhodiola pink rosavin is detected after chromatography on plates in a thin sorbent layer under UV light in the form of a violet spot. And another component of rhodiola - salidroside - appears as a reddish spot with diazotized sulfacil. Chromatography in the presence of standard samples is widely used to identify the components under study.
For individual substances, the melting point, specific rotation are determined, UV and IR spectra are recorded.
To identify phenolic glycosides, chemical transformations (hydrolysis, acetylation, methylation) and comparison of the constants of the conversion products with literature data for the putative glycoside are widely used.
Phenolic glycosides, with a free hydroxyl group, give all the reactions characteristic of phenols (reaction with ammonium iron alum, with salts of heavy metals, with diazotized aromatic amines, etc.).
If phenolic hydroxyl is glycosylated, as in salicin, the reactions are carried out after preliminary hydrolysis of the glycoside with acids or enzymes. The same qualitative reactions are used to detect phenolic glycosides in chromatograms.
In the case of chromatography in a thin layer of silica gel, the chromatograms can also be treated with 4% H 2 SO 4 in absolute ethyl alcohol. In this case, phenolic glycosides, depending on the structure, are found in the form of yellow, red, orange or blue spots.
When processing chromatograms with a solution of silver nitrate and alkali, phenolic glycosides are found in the form of brown spots with a different shade.
. Methods for the analysis of raw materials containing simple phenolic compounds.
The qualitative and quantitative analysis of raw materials is based on physical and chemical properties.
Qualitative analysis.
Phenolic compounds are extracted from plant materials with water, then the extracts are purified from accompanying substances, precipitating them with solutions of lead acetate. Qualitative reactions are performed with the purified extract.
Simple phenols and aglycones of phenologlycosides give
typical for phenolic compounds reactions:
with iron ammonium alum
with salts of heavy metals
with diazotized aromatic amines.
Specific reactions (GF X1):
- for arbutin(raw bearberry and lingonberry) use color qualitative reactions:
with crystalline iron sulfate.
The reaction is based on obtaining a complex that changes color from lilac to dark with further formation of a dark purple precipitate.
from 10% solution of sodium phosphoromolybdic acid in hydrochloric acid.
The reaction is based on the formation of a blue complex compound.
on salidroside(raw material of rhodiola rosea):
azo coupling reaction with diazotized sodium sulfacyl with the formation of a cherry-red azo dye.
salidroside azo dye
Quantitation.
For the quantitative determination of simple phenolic glycosides in medicinal plant raw materials, various methods are used: gravimetric, titrimetric, and physicochemical.
1. Gravimetric method determine the content of phloroglucides in the rhizomes of the male fern. The method is based on the extraction of phloroglucides from raw materials with diethyl ether in a Soxhlet apparatus. The extract is purified, ether is distilled off, the resulting dry residue is dried and brought to constant weight. In terms of absolutely dry raw materials, the content of phloroglucides is not less than 1.8%.
2. Titrimetric iodometric method (based on the oxidation of hydroquinone with iodine, obtained after the extraction and hydrolysis of arbutin) is used to determine the content of arbutin in raw lingonberry and bearberry. Aglycone hydroquinone is oxidized to quinone with 0.1 M iodine solution in an acidic medium and in the presence of sodium bicarbonate after obtaining purified aqueous extraction and acid hydrolysis of arbutin.
The hydrolysis is carried out with concentrated sulfuric acid in the presence of zinc dust so that the liberated free hydrogen prevents its own oxidation of hydroquinone. A starch solution is used as an indicator.
3. Spectrophotometric method used to determine the content of salidroside in raw materials of Rhodiola rosea.
The method is based on the ability of colored azo dyes to absorb monochromatic light at a wavelength of 486 nm. Determine the optical density of the colored solution obtained by the reaction of salidroside with diazotized sodium sulfacyl using a spectrophotometer. The salidroside content is calculated taking into account the specific absorption rate of the salidroside E 1% / 1 cm = 253.
Raw material base of plants containing simple phenolic compounds.
The raw material base is sufficiently well provided, the need for raw materials of bearberry, lingonberry, fern and Rhodiola rosea is covered by wild plants. Cotton species are widely cultivated.
The common lingonberry is found in the forest and tundra zones, the bearberry is found in the forest zone of the European part of the country, in Siberia and the Far East. Lingonberry grows in pine and spruce forests, in humid places, on the outskirts of peat bogs. Bearberry in dry pine moss and deciduous forests, clearings, sunny, sandy soils.
Male fern (fern) grows in the forest zone of the European part, in the mountains of the Caucasus, Pamir, Altai. Prefers shady coniferous and small-leaved forests.
The area of Rhodiola rosea covers the polar-arctic, alpine and the zone of the European part, the Urals, the Far East, mountains of southern Siberia, Altai, Sayan) and East Kazakhstan. Rhodiola rosea forms thickets and river valleys, woodlands and wet meadows. The main thickets are in Altai.
In Central Asia and the Caucasus, cotton is widely cultivated, fam. Malvaceae.
Features of collection, drying and storage of raw materials,
Lingonberry raw materials are harvested in two periods - in early spring before flowering and in autumn (during fruiting). Air-shadow or artificial drying - at a temperature of no more than 50-60 ° C in a thin layer.
Raw materials of Rhodiola rosea ("golden root") are harvested in late summer and autumn. Dried at a temperature of 40 0 С.
The raw material of the male beard is collected in the fall, dried in the shade or in dryers at a temperature of no more than 40-50 ° C.
The raw material of cotton - the bark of the roots - is harvested after the cotton harvest.
Store raw materials according to the general list in a dry, well-ventilated area.
Shelf life is 3 years. The rhizomes of the male shieldwort are stored for 1 year.
Ways of using raw materials, containing simple phenolic compounds.
From medicinal plant materials containing phenologlycosides are obtained:
1. Extemporal dosage forms:
- decoctions (raw lingonberry, bearberry, Rhodiola rosea);
Fees (raw lingonberry, bearberry, Rhodiola rosea).
2. Extraction (galenic) preparations:
- extracts:
Liquid extract (rhizomes and kornirodiola rosea);
Dense essential extract (male fern rhizomes).
3. Preparations of individual substances:
Gossypol 3% liniment and eye drops - 0.1% gossypol solution in 0.07% sodium tetraborate solution (bark of cotton roots).
Medical use of raw materials and preparations,
1. Antimicrobial, anti-inflammatory, diuretic (diuretic) action is typical for raw lingonberry and bearberry. It is due to the presence of arbutin in the raw material, which, under the influence of enzymes of the gastrointestinal tract, is split into hydroquinone and glucose. Hydroquinone, excreted in the urine, has an antimicrobial and irritant effect on the kidneys, which causes a diuretic and anti-inflammatory effect. The anti-inflammatory effect is also due to the presence of tannins.
Dosage forms from raw lingonberry and bearberry are used to treat inflammatory diseases of the kidneys, bladder (cystitis, pyelonephritis, pyelitis) and urinary tract. Decoctions of lingonberry leaves are often used to treat diseases associated with impaired mineral metabolism: urolithiasis, rheumatism, gout, osteochondrosis.
Side effect: when taking large doses, an exacerbation of inflammatory processes, nausea, vomiting, diarrhea is possible. In this regard, it is recommended to take dosage forms from raw lingonberry and bearberry, in combination with other plants.
2. Antiviral the action is characteristic of phenolic compounds of the bark of cotton roots. In medical practice, gossypol preparations
Application.
Low molecular weight phenolic compounds and their derivatives have an antiseptic and disinfectant effect.
Phenolic glycosides containing arbutin have antimicrobial and diuretic activity. The glycoside salidroside, contained in the willow bark and underground organs of Rhodiola rosea, has a stimulating and adaptogenic effect.
Salicylic acid and its derivatives are known as anti-inflammatory, antipyretic and pain relievers. So, an extract from the bark of white willow, containing salicin, has long been used in folk medicine for feverish conditions, for inflammation of the oral mucosa and upper respiratory tract (in the form of rinsing), for skin diseases (lotions).
Male fern phloroglucides act as anthelmintic agents.
in the treatment of herpes zoster, herpes simplex, psoriasis (liniment), herpetic keratitis (eye drops).
3. Adaptogenic, stimulating and tonic the effect is exerted by preparations of rhizomes and roots of Rhodiola rosea. The drugs increase performance during fatigue, hard physical work, and have an activating effect on the cerebral cortex. Used for neuroses, hypotension, vegetative-vascular dystonia, schizophrenia.
Contraindications: hypertension, fever, agitation. Do not appoint in the summer in hot weather and in the afternoon.
4. Anthelmintic (antihelminthic) the effect is exerted by preparations of male fern rhizomes.
The thick extract is a sedentary green liquid with a peculiar smell and taste. It is produced in capsules of 0.5 g. The drug is stored in a dark place according to the list B.
The use of oil laxatives (castor oil) is unacceptable, since the drug dissolves in it, is absorbed into the bloodstream and there may be poisoning. Therefore, the drug is used only in hospitals under the strict supervision of a physician.
In addition, they are characterized by properties due to the presence in the molecule of both types of functional groups and a benzene nucleus.
Phenolic acids are crystalline solids. Phenolic acids, which contain one phenolic hydroxyl, are relatively slightly soluble in cold water, but dissolve well in hot water and many organic solvents. With an increase in the number of phenolic hydroxyls, the solubility of phenolic acids increases.
Distribution in nature[ | ]
Phenolic acids are very common in nature, so they can be extracted from natural raw materials (such as, for example, blood-red hawthorn, black chokeberry, propolis). Phenolic acid is the main component (55-85%) of the residue from the distillation of wood tar pitch.
Synthesis [ | ]
Synthetic methods are often used to obtain phenolic acids. In particular, 2-hydroxybenzoic (salicylic) acid is extracted from carbon dioxide in autoclaves at 180 ° C, followed by treatment of the reaction product with hydrochloric acid, Kolbe synthesis:
C6H5ONa + C02 180 C → C6H4 (ONa) COOH; C6H4 (ONa) COOH + HC1 → C6H4 (OH) COOH + NaCl
Chemical properties[ | ]
Phenolic acids simultaneously have the properties of carboxylic acids and phenols. In addition, they are characterized by properties due to the presence of both types of functional groups and a benzene nucleus in the molecule.
Heat decomposition[ | ]
Phenolic acids decompose when heated to form phenolic compounds and carbon dioxide. For example, when heated, salicylic acid decomposes into phenol and carbon dioxide:
HOC6H4COOH → C6H5OH + CO2 salicylic acid phenol carbon dioxide
Esterification reaction (by carboxyl group)[ | ]
Phenolic acids, like carboxylic acids, are capable of forming esters due to the presence of carboxyl and hydroxyl groups.
For example, the formation of an ester of salicylic acid - acetylsalicylic acid:
HOC6H4COOH + H3C-C (= O) -O- (O =) C-CH3 → C6H4 (COOH) -O-CO-CH3 + CH3COOH salicylic acid acetic ester acetylsalicylic acid acetic acid
and the formation of an ester of gallic acid, one molecule of gallic acid reacts with its carboxyl, the other with phenyl hydroxyl. Chinese tannin is a glucoside of digalic acid and glucose.
Salt formation[ | ]
Phenolic acids, like carboxylic acids, form salts. For example, the formation of sodium salicylate in the interaction of salicylic acid and sodium hydroxide:
HOC6H4COOH + NaOH → HOC6H4COONa + H2O salicylic acid sodium salicylate
Reaction with iron (III) chloride (by phenolic group)[ | ]
Often there is a need to identify the presence of salicylic acid and other phenolic acids in canned foods. Then 2-3 ml of the test solution is placed in a test tube and a few drops of a 1% solution of iron (III) chloride are added. A violet color appears. Unlike phenol, it can also appear in an alcoholic acid solution. Coloring occurs as a result of the formation of complex salts during the interaction of phenolic groups of six phenolic acid molecules with a FeCl3 molecule.
Gallic acid readily interacts with iron (III) chloride and forms a blue-black reaction product (ink).
Nucleophilic substitution reaction with halogens[ | ]
The presence of phenolic groups (-OH) in the phenolic acid molecule allows them to enter into reactions of substitution of hydrogen atoms of the benzene nucleus for halogens under normal conditions. Benzoic acid and common aromatic acids do not enter into such reactions.
For example, bromination of salicylic acid:
HOC6H4COOH + Br2 → HO (Br) C6H3COOH + HOC6H3 (Br) COOH + 2HBr salicylic acid p-bromosalicylic acid o-bromosalicylic acid
Phenol]] th group in the salicylic acid molecule acts as a substituent of the first kind - directs atomic groups and individual atoms to replace the benzene nucleus with a hydrogen atom in the o- and n-position relative to itself.
Typical representatives and their derivatives, the use of phenolic acids in medicine and industry[ | ]
2-hydroxybenzoic acid or salicylic acid is a typical phenolic acid, it is sometimes called hydroxybenzoic acid HOC6H4COOH. Salts and esters of salicylic acid - salicylates. For the first time it was extracted from the ethers contained in the tissues of some plants - the Gaultheria procumbers essential oil. Salicylic acid is a crystalline solid. Has a bactericidal effect. Its salts and esters are widely used in medicine and veterinary medicine as medicines. Salicylic acid is widely used for the production of drugs (for example, acetylsalicylic acid, phenyl salicylate), mordants, fungicides (for example), odoriferous substances (methyl salicylate, benzyl salicylate), antiseptics in the food industry, for canning, as a reagent for colorimetric determination in iron solutions and copper, as an acid-base indicator in luminescence analysis (at pH = 2.5 ... 4.6 and in the presence of acid, blue luminescence appears), etc.
3,4,5 - Trioxybenzoic, or gallic acid - phenolic acid containing one molecule
Union of Soviet
Socialist
Republics
State Committee
THE USSR. for inventions and discoveries (23) Priority
L.G.Shakirov, E.N.Molol'neö, A. 3.Bikkulov, P.M. Zobov and T.I.Safonova (72) Authors of the invention Ufa Oil Institute (71) Applicant (54) METHOD FOR ISOLATION AND PURIFICATION OF PHENOLCARBON
The invention relates to organic chemistry, specifically to the method. used for the isolation and purification of phenolcarboxylic acids to a high degree of purity. Phenolcarboxylic acids are used as medicinal agents, growth regulators, as well as intermediates for the synthesis of effective herbicides, fungicides, formation. masses, dyes.
A known method of obtaining phenol. carboxylic acids by carboxylation of granular alkali metal phenolate at 140-200 ° C under carbon dioxide pressure, followed by dissolution of the reaction products in water, acidification of the aqueous solution with a strong mineral acid and release of poorly soluble acids (13.
However, this method is characterized by a low degree of purity of the isolated acids due to the presence in the carboxylation products of unconverted phenolates of alkali metals and phenol formed as a by-product of the reaction.
To increase the purity of the isolated target product, methods for the purification of phenolcarboxylic acids have been proposed, M.
The known method, in which the acidification of an aqueous solution. alkali metal salts of phenol carboxylic acids are produced in the presence of the surfactant f23.
However, this method, although it allows to improve the color index of the target product, is unsuitable for the isolation of phenolcarboxylic acids of high purity from the carboxylation products of alkali metal phenolates, since it does not allow the target acids to be purified from coprecipitating phenols.
Known methods for the production of phenolcarboxylic acids by carboxylation of an alkali metal phenolate in a solvent or liquid diluent, making it possible to obtain phenolcarboxylic acids of a sufficiently high degree of purification. However, these methods, although they facilitate the transportation of raw materials and reaction products, greatly complicate the technology for isolating the target product.
For example, it is proposed to carry out the process of carboxylation of phenolate. potassium in the environment of light petroleum oils. At the end of the process, the reaction mass is cooled to 150 ° C and the reaction mixture is poured with a certain amount of water. The aqueous layer after settling is separated and subjected to extraction with toluene to recover phenol, after which it is "acidified with a strong mineral acid to isolate p-hydroxybenzoic acid. Petroleum oil and toluene are further subjected to regeneration for reuse f3).
The closest to the pre) term in technical essence and the achieved result is a method for producing phenolcarboxylic acids by carboxylation of an alkali metal phenolate at 100-180 C, a carbon dioxide pressure of up to 0.5 MPa and a reaction time usually 30-90 minutes, in a polar solvent followed by cooling, distillation. solvent, dissolving the residue in water, neutralizing the solution with hydrochloric acid, extracting phenol with benzene and isolating the target product after acidifying the solution to pH 1-3. The target product has a purity of 55.8-98.1% (4).
The disadvantages of the known method are the complex technological scheme of the process, including, in addition to the unit for carboxylation of phenolates of alkali metals, a unit for the regeneration of solvents and extractants, low productivity per unit volume of the reaction device. distillation.
The aim of the invention is to simplify the process and increase the purity of obtaining phenolcarboxylic acids.
This goal is achieved by the fact that according to the method of isolation and purification of phenol carboxylic acids obtained by carboxylation of an alkali metal phenolate at an elevated temperature and pressure of carbon dioxide, followed by cooling, treatment with a lower alcohol or ketone with a carboxylation product-alcohol or ketone ratio of 1: (2- 6), respectively, and by isolating the target product by acidifying the obtained salt with mineral acid.
The purity of the target product is higher
99% (table 1).
Treatment of products obtained by carboxylation of dry alkali metal phenolates with carbon dioxide, selective solvents that dissolve unreacted feedstock and phenols formed as by-products, and non-dissolving target carboxylation products - salts of alkali metals of phenol carboxylic acids, makes it possible to obtain pure phenol carboxylic acids from the technological scheme of the production of phenolcarboxylic acids of high purity of the stage of neutralization of the reaction mass and extraction of phenol.
Example 1. 15.0 r of the reaction products obtained by carboxylation of dry sodium i-chlorophenolate at 180 C, a CO2 pressure of 1.5 MPa and a reaction time of 90 min, containing 12.50 r of sodium 5-chloro-2-hydroxybenzoaa (5x10BNa), 182 g of sodium i-chlorophenylate (p-CPNa) and 0.33 r of p-chlorophenol (p-CP) are treated
30.00 g ethanol (ratio of ethanol: carboxylation products =
2: 1 /. The resulting suspension is stirred for 15 minutes, after which it is centrifuged to separate the 5-X-2-OBNa precipitate. Acidification of the precipitate with hydrochloric acid is used to isolate
11.00 g of 5-chloro-2-hydroxybenzoic acid (5-X-2-0BK) (98.7% of potential) with a purity of 99.9b.
Example 2. 15.03 r of p-CPNa carboxylation products obtained under conditions similar to example 1, 30 containing 12.58 g of 5-X-2-OBNa, 1.83 r p-CPNa and 0.33 r p-CP, are treated
45.09 g ethanol (ratio ethanol: carboxylation products = Zr1).
The 5-X-2 OSNa precipitate is isolated similarly to Example 1. By acidifying the precipitate with hydrochloric acid, 10.77 g
5-X-2-OBK (98.1% potential) with a purity of 99.9%.
Example 2. 12.33 g of products
40 carboxylation of p-CPNa, obtained under conditions similar to example 1, containing 10.33 g of 5-X-2-OBNa, 1.50 g of p-CPNa and 0.27 g of p-CP, are treated
49.33 g ethanol (ethanol ratio of carboxylation products = 4: 1).
The 5-X-2-OBN precipitate is isolated 9.00 g
5-X-2-OBK (98.15% of potential) with a purity of 99.9%.
Example 4; 7.85 g of p-CPNa carboxylation products obtained under conditions similar to example
5.43 r 5-X-2-OBK (93.2% of potential) with a purity of 99.9b.
Example 5. 12.22 g of p-CPNa carboxylation products, obtained under conditions similar to example 1, containing 10.23 g of 5-X-2-OBNa, 1.40 g of p-CPNa and 0.26 r p-CP, are treated with 48, 88 g isopropyl alcohol
5 (ratio of isopropyl alcohol to carboxylation products = 4: 1). Sediment 5-X-2-OBNa. isolated analogously to example 1. Acidification of the precipitate with nitric acid isolate 9.01 r
5-X-2-OBK (99.0% of potential) with 5 purity 99.7%.
Example 6. 12.24 g of p-Chna carboxylation product obtained under conditions similar to example
1.49 g of p-Chna and O, 27-g of p-CP, are treated with 48.96 g of acetone (ratio of acetone: carboxylation products = 4: 1). 1. Acidification of the precipitate with hydrochloric acid yields :, t 9 0? g 5-X-2-OBK (99.0% of the potential). with a purity of 99.7%.
Example 7. 15.33 r of the reaction products obtained by carboxylation of dry potassium 2,4-dichlorophenolate (2-4-DCPA) at: 190 ° C, CO2 pressure 0.5 MPa and reaction time
Potassium 3,5-dichloro-2-hydroxybenzoate (3p5-DC-2-OBA), 6.37 g 2,4-DCPA and
1.00 g of 2,4-dichlorophenol (2,4-DCP) is treated with 45.99 g of ethanol (ethanol: carboxylation products ratio = 3: 1). The precipitate of 3,5-DCH-2-0BK is isolated analogously to example 1. By acidifying the precipitate with hydrochloric acid, 6.20 g of 3,5-dichloro-2-hydroxybenzoic acid (97.3% of potential) with a purity of 99.5% are isolated.
Example 8 12.32 g of 2,4-DCPA carboxylation products 35 obtained under conditions analogous to example
By acidifying the precipitate with hydrochloric acid, 4.89 g of 3,5-dichloro-2-hydroxyben-45-zoic acid (95.6% of potential) with a purity of 99.7% are isolated.
Example 9. 14.86 g of the reaction products obtained by carboxylation of potassium o-chlorophenolate (o-CPA) at 180 C, a CO2 pressure of 1.0 MPa and a reaction time of 150 min, containing 11 21 g of potassium 3-chloro-2-hydroxybenzoate (3 -X-2-OBK). 2.75 g of OCPA and 0.64 g of o-chlorophenol (OCP) are treated. 44.58 g of ethanol are obtained (the ratio of ethanul: carboxylation products =
3: 1). Sediment 3-X-2-OBK is isolated analogously to example 1. By acidification
"precipitate with hydrochloric acid is isolated
8.98 g 3-chloro-2-hydroxybenzoic acid (97.4% of potential) with a purity
Example 10 .. 4.53 g of o-CPA carboxylation products obtained under conditions similar to Example 9, containing 3.16 g of Z-X-2-OBA, 0.86 g of o-CPA and 0.27 g HHF is processed
18.12 g ethanol (ratio ethanol: carboxylation products = 4.1).
The precipitate 3-X-2-08K is isolated analogously to example 1. By acidifying the precipitate with hydrochloric acid, 2.46 g of 3-chloro-2-hydroxybenzoic acid (94.7% of potential) with a purity of 99.7% °
Example 11 ° 2 80 r of the reaction products obtained by carboxylation of dry sodium i-cresolate at 150 ° C, a CO pressure of 1.0 MPa and a reaction time of 20 min, containing 10.93 g of sodium 5-methyl-2-hydroxybenzoate (5 -M-2-0BBa), 0.63 g of sodium d-cresolate (p-KNa) and 1.24 g of p-cresol (p-K) are treated with 51.20 g of tanol (the ratio of ethanol: arboxylation products and 4: one). Sediment
: 5-M-2-0BNа. Is isolated analogously to example 1. By acidifying the precipitate with hydrochloric acid, 10.74 g of 5-methyl-2-hydroxybenzoic acid (5-I-2-OBA) is isolated, (98.3% of the potential) with a purity of 99.9%.
Example 12. 13.33 g of p-KNa carboxylation products obtained under conditions similar to those at-. measure. 11 containing 11.39 g of 5-M-2-08Na, 0.65 g of i-KNa and 1.29 r p-K are treated with 53.32 g of acetone (the ratio of acetone to carboxylation products = 4: 1). The 5-M-2-OBya precipitate is isolated analogously to example 11. Acidification of the precipitate with hydrochloric acid is used to isolate 11.16 g of 5-M-2-OBK (98.0% of potential) with a purity of 99.9%.
Example 13. 12.04 g of p-KNa carboxylation products obtained under conditions analogous to example 11, containing 10.28 r 5-M-2-0Bia, 0.59 g of p-Kya, and 1.17 g of p-K are treated
48.16 g of isopropyl alcohol (ratio of alcohol: carboxylation products = 4: 1). The 5-M-2-OZia precipitate is cured analogously to example 11. By acidifying the precipitate with hydrochloric acid, 10.09 r 5-M-2-OBK (98.15% et potential) with a purity of 99.7% are cured.
The main advantages of the proposed. method: simplification of the process for the production of phenolcarboxylic acids., high purity at the stage of isolation of salts of target acids by treating the products of carboxylation of alkali metals with solvents (alcohols, ketones), allowing selective isolation of salts of phenolcarboxylic acids, which makes it possible to exclude the stage of neutralization of the reaction mass from the technological scheme of production ... and phenol extraction.
Phenolcarboxylic acid
Experimental acid number
Acid number, theoretical - some
Acid purity, b
Experimental melting point, С
7 3.5-DKh-2-OBK 269.6
Note: 5-X-2-OBK - 5-chloro-2-hydroxybenzoic. acid
3, 5-DC-2-OBK - 3, 5-dichloro-2-hydroxybenzoic acid;
3-X-2-OBK -, 3-chloro-2-hydroxybenzoic acid
5-M-2-OSK - 5-methyl-2-hydroxybenzoic acid.
The formula of the invention is treated with stirring, with an organic solvent -. lower specials of isolation and purification by feyrt. or ketone at a ratio of boonic acids to ee products, nii 1: (2-6), followed by solution of eHHEitx by carboxylation with phenonium of the purified residue in water.
Sources of information taken into account in the examination
1. UK patent
50, Р 1101267+ cl. C 2 C, publ. 1968.
2. UK patent
1167095, cl. C) 2 C, published 1969.
3. French patent M 1564997, class C 07 C, publ. 1969.
55 4. Japanese patent R 43-29943, cl. 2-2355, published 1968 prototype).
Compiled by N. Kulish
Editor A. Khimchuk Tehred E. Kharitonchik Proofreader E. Roshko
Order 1788/29 Edition 4.16 Subscription
VNIIPI of the USSR State Committee for Inventions and Discoveries
113035, Moscow, Zh-35, Raushskaya nab., 4/5
Branch of PPP "Patent", Uzhgorod, st. Project, 4
: nolka obtained alkali metals with carbon dioxide at elevated pressure and temperature, by separating the impurities with an organic solvent, followed by the isolation of the target acid from the aqueous solution of the purified residue after acidification with mineral acid, that, in order to simplify the process and increase the purity of the target acid, the products of carboxylated 325, 2
Similar patents:
The invention relates to a new method for producing a mixture of 2-hydroxybenzoic acid and 4-hydroxybenzaldehyde or their derivatives, in particular to a method for producing 3-methoxy-4-hydroxybenzaldehyde-vanillin, and 3 ethoxy-4-hydroxybenzaldehyde-ethyl vanillin, in which a mixture of phenolic compounds, of which one compound (A) contains a formyl or hydroxymethyl group at position 2, and the other compound (B) contains a formyl or hydroxymethyl group at position 4, corresponding to the general formula (IIA) and (IIB), in which Y1 and Y2 are the same or different, mean one of the following groups: group - СНО; group - CH2OH; Z1, Z2, and Z3, which are identical or different, represent a hydrogen atom, a C1-C4 alkyl radical, an alkenylC2-C4 or alkoxyC1-C4 linear or branched radical, a phenyl radical, a hydroxyl, a halogen atom; is subjected to selective oxidation, in which the formyl or hydroxymethyl group at position 2 of compound (A) is oxidized to a carboxyl group and, possibly, the hydroxymethyl group of compound (B) at position 4 is oxidized to a formyl group, and the oxidation is carried out in the presence of a base in an amount from 2 to 10 moles per mole of phenolic compounds (IIA) and (IIB), and a catalyst based on palladium and / or platinum, and a mixture of 2-hydroxybenzoic acid and 4-hydroxybenzaldehyde or their derivatives is obtained
The invention relates to new compounds of formula (I), in which Ar is phenyl, furanyl, thiophenyl, thiazolyl, pyridinyl; R1 is independently selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, halogen, and nitro; R2 is independently selected from the group consisting of hydrogen and halogen; R4 is hydroxy or a pyrrolidine-2-carboxylic acid, piperidine-2-carboxylic acid or 1-aminocyclopentanecarboxylic acid residue linked through the nitrogen atom of the amino acid residue; n means 0, 1, 2, 3, 4 or 5; m means 0, 1, 2, 3 or 4; p is 0 and s is 0, or their pharmaceutically acceptable salts, provided that the compound is not S-1-pyrrolidine-2-carboxylic acid, 5- (biphenyl-4-yloxymethyl) furan-2-carboxylic acid , 3- (biphenyl-4-yloxymethyl) benzoic acid, 2- (biphenyl-3-yloxymethyl) benzoic acid, 4- (biphenyl-3-yloxymethyl) benzoic acid, 4- (biphenyl-4-yloxymethyl) benzoic acid, 5 - (biphenyl-4-yloxymethyl) thiophene-2-carboxylic acid
In addition, they are characterized by properties due to the presence in the molecule of both types of functional groups and a benzene nucleus.
Phenolic acids are crystalline solids. Phenolic acids, which contain one phenolic hydroxyl, are relatively slightly soluble in cold water, but dissolve well in hot water and many organic solvents. With an increase in the number of phenolic hydroxyls, the solubility of phenolic acids increases.
Distribution in nature
Synthesis
Synthetic methods are often used to obtain phenolic acids. In particular, 2-hydroxybenzoic (salicylic) acid is extracted from sodium phenolate and carbon dioxide in autoclaves at 180 ° C, followed by treatment of the reaction product with hydrochloric acid, Kolbe synthesis:
C6H5ONa + C02 180 C → C6H4 (ONa) COOH; C6H4 (ONa) COOH + HC1 → C6H4 (OH) COOH + NaCl
Chemical properties
Phenolic acids simultaneously have the properties of carboxylic acids and phenols. In addition, they are characterized by properties due to the presence of both types of functional groups and a benzene nucleus in the molecule.
Heat decomposition
Phenolic acids decompose when heated to form phenolic compounds and carbon dioxide. For example, when heated, salicylic acid decomposes into phenol and carbon dioxide:
HOC6H4COOH → C6H5OH + CO2 salicylic acid phenol carbon dioxide
Esterification reaction (by carboxyl group)
Phenolic acids, like carboxylic acids, are capable of forming esters due to the presence of carboxyl and hydroxyl groups.
For example, the formation of an ester of salicylic acid - acetylsalicylic acid:
HOC6H4COOH + H3C-C (= O) -O- (O =) C-CH3 → C6H4 (COOH) -O-CO-CH3 + CH3COOH salicylic acid acetic ester acetylsalicylic acid acetic acid
and the formation of an ester of gallic acid, one molecule of gallic acid reacts with its carboxyl, the other with phenyl hydroxyl. Chinese tannin is a glucoside of digalic acid and glucose.
Salt formation
Phenolic acids, like carboxylic acids, form salts. For example, the formation of sodium salicylate in the interaction of salicylic acid and sodium hydroxide:
HOC6H4COOH + NaOH → HOC6H4COONa + H2O salicylic acid sodium salicylate
Reaction with iron (III) chloride (by phenolic group)
Often there is a need to identify the presence of salicylic acid and other phenolic acids in canned foods. Then 2-3 ml of the test solution is placed in a test tube and a few drops of a 1% solution of iron (III) chloride are added. A violet color appears. Unlike phenol, it can also appear in an alcoholic acid solution. Coloring occurs as a result of the formation of complex salts during the interaction of phenolic groups of six phenolic acid molecules with a FeCl3 molecule.
Gallic acid readily interacts with iron (III) chloride and forms a blue-black reaction product (ink).
Nucleophilic substitution reaction with halogens
The presence of phenolic groups (-OH) in the phenolic acid molecule allows them to enter into reactions of substitution of hydrogen atoms of the benzene nucleus for halogens under normal conditions. Benzoic acid and common aromatic acids do not enter into such reactions.
For example, bromination of salicylic acid:
HOC6H4COOH + Br2 → HO (Br) C6H3COOH + HOC6H3 (Br) COOH + 2HBr salicylic acid p-bromosalicylic acid o-bromosalicylic acid
Phenol]] th group in the salicylic acid molecule acts as a substituent of the first kind - directs atomic groups and individual atoms to replace the benzene nucleus with a hydrogen atom in the o- and n-position relative to itself.
Typical representatives and their derivatives, the use of phenolic acids in medicine and industry
2-hydroxybenzoic acid or salicylic acid is a typical phenolic acid, it is sometimes called hydroxybenzoic acid HOC6H4COOH. Salts and esters of salicylic acid - salicylates. For the first time it was extracted from the ethers contained in the tissues of some plants - the Gaultheria procumbers essential oil. Salicylic acid is a crystalline solid. Has a bactericidal effect. Its salts and esters are widely used in medicine and veterinary medicine as medicines. Salicylic acid is widely used for the production of drugs (for example, acetylsalicylic acid, phenyl salicylate), mordants, fungicides (for example, salicylanilide), odoriferous substances (methyl salicylate, benzyl salicylate), antiseptics in the food industry, for canning, as a reagent for colorimetric determination iron and copper, as an acid-base indicator in luminescence analysis (at pH = 2.5 ... 4.6 and in the presence of acid, blue luminescence appears), etc.
3,4,5 - Trioxybenzoic, or gallic acid - phenolic acid containing one molecule
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