Adipic acid (1,4-butanedicarboxylic acid) HOOC(CH 2) 4 COOH, molecular weight 146.14; colorless crystals; m.p. 153°C, b.p. 265°C/100 mmHg Art.; easily sublimes; d 4 18 = 1.344; decomposition point 210-240°C; () = 4.54 (160°С), 2.64 (193°С); ; , . Solubility in water (g per 100 g): 1.44 (15°C), 5.12 (40°C), 34.1 (70°C). Solubility in ethanol, in ether - limited.

Adipic acid has all the chemical properties characteristic of carboxylic acids. Forms salts, most of which are soluble in water. Easily esterified to mono- and diesters. Forms polyesters with glycols. Salts and esters adipic acid are called adipates. When interacting with NH 3 and amines adipic acid gives ammonium salts, which, when dehydrated, turn into adipamides. With diamines, adipic acid forms polyamides, with NH 3 in the presence of a catalyst at 300-400 ° C - adipodinitrile.

When adipic acid is heated with acetic anhydride, a linear polyanhydride is formed BUT [--CO (CH 2 ) 4 SOO--] n H, during the distillation of which at 210°C an unstable cyclic anhydride (formula I) is obtained, which at 100°C again turns into a polymer. Above 225 °C, adipic acid cyclizes to cyclopentanone (II), which is more easily obtained by pyrolysis of calcium adipate.

In industry, adipic acid is obtained mainly by a two-stage oxidation of cyclohexane. At the first stage (liquid-phase oxidation with air at 142-145°C and 0.7 MPa), a mixture of cyclohexanone and cyclohexanol is obtained, separated by distillation. Cyclohexanone is used to produce caprolactam. Cyclohexanol is oxidized with 40-60% HNO 3 at 55°C (NH 4 VO 3 catalyst); the yield of adipic acid is 95%.

Adipic acid can also be obtained:

a) oxidation of cyclohexane with 50-70% HNO 3 at 100-200°C and 0.2-1.96 MPa or N 2 O 4 at 50°C;

b) oxidation of cyclohexene with ozone or HNO 3 ;

c) from THF according to the scheme:

d) carbonylation of THF to adipic anhydride, from which the acid is obtained by the action of H 2 O.

The use of adipic acid

The main area of ​​application for adipic acid is the production of polyamide resins and polyamide fibers, and these markets have long been established and are experiencing fierce competition from polyester and polypropylene.

The use of adipic acid in the production of polyurethanes is increasing. Now the growth rate of production and consumption of polyurethanes exceeds the growth rate of production and consumption of polyamides, especially polyamide fibers. For example, the demand for adipic acid from Western European polyurethane producers is constantly increasing, and today its growth rate is approximately 12-15% per year. However, the demand for polyamide (nylon) for plastics production is also increasing, especially in Asian region. This is explained by the fact that for the production of polyurethanes in the Asia-Pacific countries, polyethers are more often used, in the synthesis of which adipic acid does not take part, therefore up to 85% of adipic acid is used here in the production of polyamides. This feature has a ripple effect on the demand for adipic acid in the region, so the average annual growth rate of global demand for this product is projected at 3-3.5%. In Russia own production adipic acid is not yet available, although there are very favorable conditions for this: a developed raw material base (cyclohexanol, cyclohexanone, nitric acid), there are large consumers of end products (plasticizers, monomers). The prospective need for adipic acid for Russia is estimated at several tens of thousands of tons per year. AT Russian Federation adipic acid is used for the production of plasticizers, polyamides, pharmaceuticals, polyurethanes.

So, adipic acid is a strategically and economically important raw material in the production of polyhexamethylene adipamide (~ 90% of the acid produced), its esters, polyurethanes; food additive (gives a sour taste, in particular in the production of soft drinks). That is, products based on adipic acid are widely used in the production of polyamides, plasticizers, polyesters, polyester resins for PU, PPU, in the industrial processing of glass, in the radio-electronic and electrical industry, in the production of disinfectants, in the food and chemical-pharmaceutical industries, in the production of varnishes and enamels, solvents, self-curing compositions.

Adipic acid

Product chemical formula: C 6 H 10 O 4 / HOOC (CH 2) 4 COOH

Trade designations of the product:

• Adipic acid

• 1,4-Butanedicarboxylic acid
• 1,6-Hexanedioic Acid
• Acifloctin
• Hexanedioic acid
• E-355

Product description:

Adipic acid (also called hexanedioic acid) is a white crystalline compound of a dicarboxylic acid with a straight C6 chain; Slightly soluble in water and soluble in alcohol and acetone. Almost all commercial adipic the acid is obtained from cyclohexane through two successive oxidation processes. The first oxidation is the reaction of cyclohexane with oxygen in the presence of cobalt or manganese catalysts at a temperature of 150-160°C, which form cyclohexanol and cyclohexanone. The intermediates are then further reacted with nitric acid and air with a catalyst (copper or vanadium) or without nitric acid. Cyclohexane can be obtained by hydrogenation of benzene. Other methods exist, such as reactions using phenol, butadiene, and various fats as starting material. Consumption adipic acid almost 90% is associated with the production of nylon by polycondensation with hexamethylenediamine. Nylon, which has a protein-like structure, is further processed into fibers for use in carpets, car tires and clothes. Adipic acid used in the production of plasticizer components and lubricants. Used in the manufacture of polyester polyols for polyurethane systems. Adipic acid food grade is used as a gelling aid, acidifier, leavening agent and buffering agent. Adipic acid has two carboxylic acids, -COOH, groups that can give two kinds of salts. Its derivatives, acyl halides, anhydrides, esters, amides and nitriles are used in the production of end products such as flavors, internal plasticizers, pesticides, dyes, textile treatments, fungicides and pharmaceuticals through further substitution reactions, catalytic reduction, metallization Hydride reduction, diborane reduction, keto formation with organometallic reagents, electrophilic bonding in oxygen, and condensation. A dicarboxylic acid is a compound containing two carboxylic acid groups, -COOH. Straight chain examples are shown in the table. General formula is HOOC(CH2)nCOOH where n is oxalic acid, n = 1 for malonic acid, n = 2 for succinic acid, n = 3 for glutaric acid, etc. In the replacement nomenclature of their name Formed by adding -dioic "as a suffix to the name of the parent compound. They can give two types of salts, since they contain two carboxyl groups in their molecules. The range of carbon chain lengths is from 2, but longer than C 24 is very rare. The term long chain refers usually to C 12 to C 24. Carboxylic acids have industrial applications directly or indirectly through halogen acids, esters, salts and anhydride forms, polymerization, etc. Dicarboxylic acids can give two kinds of salts or esters, since they contain two carboxyl groups in a single molecule This is useful in a variety of industrial applications There are nearly endless esters derived from carboxylic acids Esters are formed by removing water from an acid and an alcohol . Esters of carboxylic acid are used in both a variety of and indirect applications. Lower chain esters are used as flavoring base materials, plasticizers, solvent carriers and binding agents. Higher chain compounds are used as components in metalworking fluids, surfactants, lubricants, detergents, lubricants, emulsifiers, wetting agents, textile treatments, and emollients. They are also used as intermediates for various target compounds. Almost infinite esters provide a wide range of viscosities, specific gravity, vapor pressure, boiling point and other physical and Chemical properties to select the correct application.

Physical and chemical properties of Adipic acid.

	index	meaning
	Physical state Adipic acid	solid at 20°C
	The form Adipic acid	crystalline powder
	Color Adipic acid	white
	Smell Adipic acid	weak
	Molecular weight Adipic acid	146.14 g/mol
	Melting temperature Adipic acid	150.85°C
	Boiling range Adipic acid	337.5°C
	Flash point Adipic acid	196°C
	Flammability Adipic acid	Not flammable
	Explosive properties Adipic acid	Non-explosive
	Steam pressure Adipic acid	0.097 hPa at 18.5 °C
	Solubility Adipic acid in water	23 g/l at 25°C
	Water distribution coefficient in Adipic acid	0.09 at 20°C
	Auto ignition temperature Adipic acid	400°C

Transportation and storage of Adipic acid:

crystalline adipic acid tends to form conglomerates. Parameters that can influence the formation of conglomerates include not only storage time, but also humidity, temperature, and particle size. It is recommended that the molten adipic acid was subject to storage due to its parameters. Store and transport under nitrogen atmosphere. The main risk of dealing with adipic acid is an explosion hazard. Adipic acid dust suspended in the air can ignite at temperatures of 500-550°C. According to the Bureau of Mines, the dust adipic acid has an explosion severity index of 1.9 and a relative explosion rating. Crystal adipic acid must be stored under a nitrogen atmosphere or in a mixture of nitrogen and air with an oxygen content of less than 10%. During pneumatic conveying adipic acid both nitrogen and air can be used. However, in the latter case, precautions must be taken to avoid the risk of dust ignition. In particular, transport equipment must have blast holes to dissipate the force of any possible explosion, and all equipment must be properly grounded to prevent static charges. Solid adipic acid and her aqueous solutions attack mild steel even at room temperature, but do not significantly affect stainless steel and aluminium.

Product Applications:

1. In medicine. Adipic acid was incorporated into controlled release prescription drug matrix tablets to provide pH independent release for both weakly basic and weakly acidic drugs. He was also included in polymer coating hydrophilic monolithic systems to modulate the pH of the intracellular layer, resulting in the release of a zero order hydrophilic drug. Enteric pH disintegration of enteric shellac is reported to be improved when adipic acid is used as a pore-forming agent without affecting acid release. Other controlled release formulations include adipic acid in order to obtain a release profile at the end of the burst. Adipic acid used to make bisobrin antifibrinolytic.
2. AT Food Industry. Small but significant quantities adipic acid used as a food ingredient as a flavoring and gelling agent. It is used in some calcium carbonate antacids to make them tart. As an acidifier in baking powders, it avoids the undesirable hygroscopic properties of tartaric acid. Adipic acid, rarely found in nature, occurs naturally in beets, but is not an economical source of commerce compared to industrial synthesis.
3. At home. Adipic acid buy and applied in the manufacture of a wide range of products for use in the home, such as carpets, indoor furnishings, and fragrances.
4. In an office environment. Adipic acid buy and apply in the production of office floor coverings and furniture.
5. in the automotive industry. Adipic acid used in the production stages of a wide range of lightweight automotive parts, as well as seat upholstery and car floor mats.
6. in daily recreational activities. Adipic acid It is used in the production of specialized footwear, equipment for recreation, as well as recreational specialized clothing.
7. BUT dipic acid and is used in the production of nylon 6-6, which is widely used throughout the world.
8. Adipic acid used in the production of a wide range of adsorbents and absorbents.
9. Adipic acid used in the production of finishing materials.
10. Adipic acid used in the manufacture of lubricants and lubricants.
11. Hexanedioic acid used in the manufacture of plasticizers.
12. Hexanedioic acid used in the manufacture of paints and specialized paint additives.
13. Hexanedioic acid It is used as an agent-separator of solids in industrial production.

ESSAY

"Adipic acid"

Donetsk, 2013

Introduction ................................................ ................................................. ............3

1. Physical and chemical properties of adipic acid .......................................... 4

2. Importance of production. The use of adipic acid ............................... 6

3. Methods for obtaining adipic acid .............................................................. ........7

4. Development of adipic acid production and modern technological aspects .............................................................. .........................................ten

5. Production of adipic acid by oxidation of cyclohexanol..........11

6. Batch and continuous methods for the production of adipic acid .................................................... ................................................. ....................eighteen

Tubular type reactor ............................................................... ................................................21

Conclusions................................................. ................................................. ............24

List of references .............................................................................. ................25

Introduction

Adipic acid is one of the most important products of the chemical industry.

The main area of ​​application of adipic acid is the production of polyamide resins and polyamide fibers, and these markets have long been formed and are experiencing fierce competition from polyester and polypropylene.

The use of adipic acid in the production of polyurethanes is increasing. Now the growth rate of production and consumption of polyurethanes exceeds the growth rate of production and consumption of polyamides, especially polyamide fibers. In Ukraine and Russia, there is no own production of adipic acid yet, although there are very favorable conditions for this: a developed raw material base (cyclohexanol, cyclohexanone, nitric acid), there are large consumers of end products (plasticizers, monomers). The prospective need for adipic acid is estimated at several tens of thousands of tons per year.

So, adipic acid is a strategically and economically important raw material in the production of polyhexamethylene adipamide (~ 90% of the acid produced), its esters, polyurethanes; food additive (gives a sour taste, in particular in the production of soft drinks). That is, products based on adipic acid are widely used in the production of polyamides, plasticizers, polyesters, polyester resins for PU, PU foam, in the industrial processing of glass, in the electronic and electrical industries, in the production of disinfectants, in the food and chemical-pharmaceutical industries, in obtaining varnishes and enamels, solvents, self-curing compositions.

This paper highlights the development and state of production of adipic acid, environmental aspects production, its physical and chemical properties, fields of application.

Physical and chemical properties of adipic acid

Adipic acid (hexanedioic acid) HOOC (CH 2) 4 COOH is a dibasic limiting carboxylic acid. It has all the chemical properties characteristic of carboxylic acids.

Table number 1. Physical and chemical properties of adipic acid

Nomenclature
Trivial name	Adipic acid
Systematic name	Hexanedioic acid or 1,4-butanedicarboxylic acid
Gross formula	C 6 O 4 H 10
Properties
Molar mass	146.14 g/mol
Appearance	colorless crystals
Density	1.36 g/cm3
Solubility in water (g per 100g)	1.44 (15 0 С); 5.12 (40 0 С); 34.1 (70 0 С)
Solubility in ethanol, acetone, diethyl ether	limited soluble
Melting temperature	153 0 C
Decomposition temperature	210-240 0 C
Boiling point (at 100 mmHg)	265 0 С
Decarboxylation temperature	300-320 0 С
Acidity constants	k 1\u003d 3.7 10 -5, k2\u003d 0.53 10 -5
Dynamic viscosity	4.54 MPa s (160 0 С)
Absolute value dipole moment	13.47 10 -30 C m
Enthalpy of combustion	-2800kJ/mol
Enthalpy of fusion	16.7 kJ/mol
Enthalpy of vaporization	18.7 kJ/mol

Adipic acid has all the chemical properties characteristic of carboxylic acids

when reacting with various metals, their basic hydroxides and oxides gives the corresponding salts.

Can displace weaker acid from its salt.

In the presence of an acid catalyst, adipic acid reacts with alcohols. In this case, esters are formed.

When heated, ammonium salts of adipic acid form their amides.

· under the influence of SOCl 2 adipic acid is converted into the corresponding acid chloride.

Easily esterified to mono- and diesters;

Forms polyesters with glycols. Salts and esters of adipic acid are called adipates;

when interacting with NH 3 and amines, adipic acid gives ammonium salts, which, upon dehydration, turn into adipamides;

With diamines, adipic acid forms polyamides;

· with NH 3 in the presence of a catalyst at 300-400 °C - adipodinitrile.

· when adipic acid is heated with acetic anhydride, a linear polyanhydride HO[-CO(CH2)4COO-]nH is formed, upon distillation of which at 210°C an unstable cyclic anhydride is obtained, which at 100°C again turns into a polymer. Above 225 °C, adipic acid cyclizes to cyclopentanone (II), which is more easily obtained by pyrolysis of calcium adipate.

Federal Agency for Education

State educational institution higher professional education

Samara State Technical University

Department:"Organic chemistry"

“SYNTHESIS OF ADIPIC ACID”

Course work

Completed:

Supervisor:

Samara, 2007

1. Introduction

1.1. Properties of adipic acid

1.2. The use of adipic acid

1.3. Synthesis of adipic acid

2. Literary review. Methods for obtaining dicarboxylic and polycarboxylic acids

2.1. Carboxylation and alkoxycarbonylation

2.2. Condensation reactions

2.3. Michael reactions

2.4. Oxidative Methods

3. Experimental technique

Bibliography

1. Introduction

1.1. Properties adipic acid

Adipic acid (1,4-butanedicarboxylic acid) HOOC(CH 2) 4 COOH, molecular weight 146.14; colorless crystals; m.p. 153°C, b.p. 265°C/100 mmHg Art.; easily sublimes; d 4 18 = 1.344; decomposition point 210-240°C;

() = 4.54 (160°С), 2.64 (193°С); ; , , . Solubility in water (g per 100 g): 1.44 (15°C), 5.12 (40°C), 34.1 (70°C). Solubility in ethanol, in ether - limited.

Adipic acid has all the chemical properties characteristic of carboxylic acids. Forms salts, most of which are soluble in water. Easily esterified to mono- and diesters. Forms polyesters with glycols. Salts and esters of adipic acid are called adipinates. When interacting with NH 3 and amines, adipic acid gives ammonium salts, which, upon dehydration, turn into adipamides. With diamines, adipic acid forms polyamides, with NH 3 in the presence of a catalyst at 300-400 ° C - adipodinitrile.

When adipic acid is heated with acetic anhydride, a linear polyanhydride is formed BUT [-CO (CH 2) 4 COO-] n H, during the distillation of which at 210°C an unstable cyclic anhydride (formula I) is obtained, which at 100°C again turns into a polymer. Above 225 °C, adipic acid cyclizes to cyclopentanone (II), which is more easily obtained by pyrolysis of calcium adipate.

In industry, adipic acid is obtained mainly by a two-stage oxidation of cyclohexane. At the first stage (liquid-phase oxidation with air at 142-145°C and 0.7 MPa), a mixture of cyclohexanone and cyclohexanol is obtained, separated by distillation. Cyclohexanone is used to produce caprolactam. Cyclohexanol is oxidized with 40-60% HNO 3 at 55°C (NH 4 VO 3 catalyst); the yield of adipic acid is 95%.

Adipic acid can also be obtained:

a) oxidation of cyclohexane with 50-70% HNO 3 at 100-200°C and 0.2-1.96 MPa or N 2 O 4 at 50°C;

b) oxidation of cyclohexene with ozone or HNO 3 ;

c) from THF according to the scheme:

d) carbonylation of THF to adipic anhydride, from which the acid is obtained by the action of H 2 O.

1.2. Application adipic acid

The main area of ​​application of adipic acid is the production of polyamide resins and polyamide fibers, and these markets have long been formed and are experiencing fierce competition from polyester and polypropylene.

The use of adipic acid in the production of polyurethanes is increasing. Now the growth rate of production and consumption of polyurethanes exceeds the growth rate of production and consumption of polyamides, especially polyamide fibers. For example, the demand for adipic acid from Western European polyurethane producers is constantly increasing, and today its growth rate is approximately 12-15% per year. However, demand for polyamide (nylon) for plastics is also on the rise, especially in the Asian region. This is explained by the fact that for the production of polyurethanes in the Asia-Pacific countries, polyethers are more often used, in the synthesis of which adipic acid does not take part, therefore up to 85% of adipic acid is used here in the production of polyamides. This feature has a ripple effect on the demand for adipic acid in the region, so the average annual growth rate of global demand for this product is projected at 3-3.5%. In Russia, there is no own production of adipic acid, although there are very favorable conditions for this: a developed raw material base (cyclohexanol, cyclohexanone, nitric acid), there are large consumers of end products (plasticizers, monomers). The prospective need for adipic acid for Russia is estimated at several tens of thousands of tons per year. In the Russian Federation, adipic acid is used for the production of plasticizers, polyamides, pharmaceuticals, and polyurethanes.

So, adipic acid is a strategically and economically important raw material in the production of polyhexamethylene adipamide (~ 90% of the acid produced), its esters, polyurethanes; food additive (gives a sour taste, in particular in the production of soft drinks). That is, products based on adipic acid are widely used in the production of polyamides, plasticizers, polyesters, polyester resins for PU, PU foam, in the industrial processing of glass, in the electronic and electrical industries, in the production of disinfectants, in the food and chemical-pharmaceutical industries, in obtaining varnishes and enamels, solvents, self-curing compositions.

1.3. Synthesis adipic acid

Into a 5 liter round bottom flask equipped with a mechanical stirrer, thermometer and separating funnel ca. In 1 liter, place 2100 g (16.6 mol) of 50% nitric acid (specific gravity 1.32; in fume hood). The acid is heated almost to boiling and 1 g of ammonium vanadate is added. Start the stirrer and slowly add 500 g (5 mol) of cyclohexanol through a separating funnel. First, 40-50 drops of cyclohexanol are added and the reaction mixture is stirred until the reaction starts (4-5 min), which becomes noticeable by the evolution of nitrogen oxides (Note 3). Then the reaction flask is placed in an ice bath, the contents of the flask are cooled until the temperature of the mixture reaches 55-60 0 C. After that, cyclohexanol is added as soon as possible, maintaining the temperature within the limits indicated above. Toward the end of the oxidation (after 475 g of cyclohexanol had been added), the ice bath was removed; sometimes the flask even has to be heated in order to maintain the required temperature and to avoid cyclization of the adipic acid.

Stirring is continued for another hour after the addition of the entire amount of cyclohexanol. The mixture is then cooled to 0, the adipic acid is suction filtered, washed with 500 ml ice water and air dry overnight. The output of white crystals with so pl. 146-149 0 is 395-410g. By evaporation of the mother liquors, another 30-40 g of product with m.p. 141-144 0 С (note 4). Total yield of crude adipic acid: 415-440g, or 58-60% theoretical. (note 6). The resulting product is reasonably pure for most purposes; however, a purer product can be obtained by recrystallization of crude adipic acid from 700 ml of concentrated nitric acid sp. weight 1.42. cleaning losses are about 5%. Recrystallized adipic acid melts at 151-152 0 (Notes 6 and 7).

Notes.

1. It is suggested not to use a catalyst if the temperature of the reaction mixture, after the start of the reaction, is maintained at 85-90 0 (Hartman, private communication).

2. Used technical cyclohexanol, practically free of phenol. More than 90% of the product boiled within 158-163 0 .

3. It is very important that the oxidation begin before a significant amount of cyclohexanol is added, otherwise the reaction may become violent. The reaction must be carried out in a well-functioning fume hood.

4. Nitric acid mother liquors contain significant amounts of adipic acid mixed with glutaric and succinic acids. It turned out that the separation of these acids by crystallization is practically impractical. However, if nitric acid is removed by evaporation, and the remaining mixture of acids is esterified with ethyl alcohol, then a mixture of ethyl esters of succinic (bp. 121-126 0 /20mm), glutaric (bp. 133-138 0 /20mm) and adipic b.p. (142-147 0 /20mm) acids. These esters can be successfully separated by distillation.

5. The following modified recipe may give a better outcome. In a 3-liter flask equipped with a stirrer, reflux condenser and addition funnel, fixed in asbestos stoppers impregnated with liquid glass, place 1900 ml of 50% nitric acid (1262 ml of nitric acid sp. weight 1.42, diluted to 1900 ml) and 1 g of ammonium vanadate. The flask is placed on water bath, heated to 50-60 0 , and very slowly, with the stirrer running, add 357 g (3.5 mol.) of technical cyclohexanol so that the bath temperature is maintained at 50-60 0 . This operation lasts 6-8 hours. The reaction is terminated by heating the water bath to boiling until the evolution of nitrogen oxides ceases (about 1 hour). The hot reaction mixture is siphoned off and allowed to cool. Yield of crude adipic acid: 372g (72% theoretical).

4.8 out of 5

Studying the composition of the product described on its packaging, we can also find adipic acid among the ingredients. What is this substance and does it pose a health risk?

Adipic acid is one of the acidity regulators, it allows products to retain marketable qualities longer, protects against oxidation and spoilage. Sometimes it is used not only to extend the shelf life of the product, but also to give it a sour taste. Adipic acid is widely used in the production of soft drinks, chewing gums, dry mixes for baking cakes, often it is part of the fillings for cakes and jelly.

What is adipic acid

Adipic acid is one of the representatives of carboxylic acids. Another name for this substance is hexanedioic acid. It is a small colorless crystals, sour in taste. In nature, this substance is found in small quantities in red beets.

For industrial needs, adipic acid is most often obtained by a two-stage catalytic oxidation of cyclohexane. In addition, the substance is often obtained as a result of the interaction of cyclohexane with nitric acid or ozone. Adipic acid easily forms salts with a high degree of solubility in water.

The hazard class of adipic acid, according to GOST of January 12, 2005, is the third. It is considered to be of low toxicity. Adipic acid is also a combustible substance. It ignites at 320 degrees, and at a temperature of about 410 degrees it is capable of self-ignition. Acid dust is explosive.

The use of adipic acid in the food industry

As food additive adipic acid is allowed to be used in EU countries. However, due to the fact that the effect of this substance on human body not fully studied, some countries have banned its use in the food industry. In Russia, this food additive is not listed among the prohibited ones, but its scope is strictly limited.

In the Russian Federation, it is allowed to use adipic acid:

• in the production of dry flavored desserts - in the amount of not more than 1 g per kilogram of the product;
• in fillings and finishing semi-finished products for baking - no more than 2 g per kilogram of the product;
• in jelly-like desserts - no more than 6 g per kilogram;
• in dry mixes for preparing drinks - no more than 10 g per 1 kilogram of dry mix.

A relatively safe intake of adipic acid has been established. It should not exceed 5 mg per 1 kg of body weight per day. The maximum allowable content of a substance in water is 2 mg per 1 liter. In the air, per 1 cubic meter, may contain no more than 4 mg of this substance. At higher concentrations, the acid can irritate the mucous membranes of the upper respiratory tract and eyes (provided it is airborne in the form of aerosols or dust).

After acid intake with food or drink, adipates for the most part are excreted in the urine. A smaller part is broken down in the body and excreted with exhaled air.

The study of the effects of this acid on the human body continues. However, there are already grounds for believing that the consumption of such a substance in large quantities than 5 mg per 1 kg of body weight can cause serious damage to health.

Applications of adipic acid in other fields

A negligible fraction of the world's adipic acid is used as a dietary supplement, and in total, about 3 million tons of this substance are produced annually on the planet.

Most of the acid, about 90%, is used for the production of synthetic polyamide fibers (for example, the famous nylon) and polyurethanes. Polyamide fibers are different high strength, hygroscopicity, resistance to abrasion. They are used to make fabrics.

Polyurethanes are inexpensive and at the same time have strength and resistance to aggressive environments, due to which they are often used as substitutes for metal, rubber, rubber or plastic. Apart from wide application in instrumentation and mechanical engineering, polyurethanes are used for the manufacture of medical prostheses.

Adipic acid is used in the production of diesters and dyes, insecticides, and some types of lubricants. In addition, adipic acid is used in the production of plastics as a plasticizer. This substance is widely used in paper and cardboard production, and is also necessary component many cleaning products.

Since the hazard class of adipic acid is the third (this means low toxicity and danger to the human body), then given substance included as a main ingredient in most descaling products for various household appliances and kitchen equipment.

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