Adipic acid or 1,6-hexanedioic acid . It is an organic compound of formula (CH 2 ) 4 (CO 2 H) 2 ; the most important dicarboxylic acid from the industrial perspective.
Despite its name (from the Latin adipis, body fat), this acid is not a constituent of natural fats, but it is found as a product of oxidative degradation of oils.
Summary
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- 1 Physical properties
- 2 Chemical properties
- 1 Reaction mechanism for the production of nylon
- 3 Obtaining
- 4 Alternative production methods
- 5 Applications
- 6 Health effects
- 1 Environmental toxicity
- 7 Sources
Physical properties
Adipic acid has a molar mass of 146.1g. and it is made up of carbon , hydrogen and oxygen . A sample of 3,276g. of this contains 1,615g. carbon and 0.226g hydrogen. According to this information, the molecular formula of adipic acid can be:
- a) C 5H 22O 4
- b) C 6H 10O 4
- c) C 6H 26O 3
- d) C 7H 14O 3
Adipic acid is also known as hexanedioic acid; 1,4-butanedicarboxylic acid.
- Appearance: White crystalline powder.
- Smell: Odorless.
- Solubility: Slightly soluble in water.
- Density: 1.36
- pH: 3.2 (0.1% soln. aq.) @ 25 º C
- % Volatiles by Volume @ 70ºF (21ºC): 0
- Boiling Point: 337 º C (639 º F) @ 760 mm Hg (decomposes)
- Melting Point: 152º C (306º F)
- Vapor Density ( Air= 1): 5.04
- Vapor Pressure (mm Hg): 1 @ 159.5 º C (320 º F)
- CAS No .: 124-04-9
- Molecular Weight: 146.14
- Chemical Formula: C 6H 10 O 4
- Product Key: A0074, A0075, A0076
About 2.5 billion kilograms of this crystalline white powder are produced annually, primarily as a precursor to nylon production . Adipic acid rarely occurs in nature .
Chemical properties
Reaction mechanism for the production of nylon
Obtaining
It was obtained by Dieterle by oxidation of castor oil with nitric acid . It was synthesized in 1902 from tetramethylene bromide. Historically, adipic acid has been prepared in different ways using oxidation. Currently this acid is produced by the mixture of cyclohexanol and cyclohexanone called ” KA oil “, which comes from the abbreviation “ketone- alcohol ” (” ketone- alcohol”). KA oil is oxidized with nitric acid to process adipic acid.
At the beginning of the reaction, cyclohexanol is converted to ketone, releasing nitrous oxide :
HOC 6 H 11 + HNO 3 → OC 6 H 10 + HNO 2 + H 2 O
Among its various reactions, cyclohexane becomes nitrous, determining the stage for cleavage of the CC bond:
HNO 2 + HNO 3 → NO + NO 3 – + H 2 O
OC 6 H 10 + NO + → OC 6 H 9 -2-NO + H +
Products derived from the method include glutaric and succinic acids.
Related processes start from cyclohexanol, which is obtained from the hydrogenation of phenol .
Alternative production methods
Many methods have been developed by the carbonylation of butadiene. For example, hydrocarboxylation proceeds as follows:
CH 2 = CHCH = CH 2 + 2 CO + 2 H 2 O → HO 2 C (CH 2 ) 4CO 2 H
Applications
Adipic acid is a chemical compound used for crosslinking of water based emulsions, and for fiber processing. It can also be used as a hardener for some polyepoxides. Most of the 2.5 trillion kg of adipic acid produced annually is used as a monomer for nylon production by a polycondensation reaction forming nylon 6,6. It is a compound widely used in the synthetic fabric industry.
Another of the most relevant applications also involves polymers , with which the monomer used in the production of polyurethane and its esters are plasticizers, especially in PVC. It is used in the Metallurgy Industry as a precipitating and resolving agent for the rare ear.
- Light industry: removing rust bleaching products from leather, wood and aluminum
- Printing Industry: Dyeing Agent
- Medicine Industry: To make hydrochloric acid etc.
- Others: As agent and laboratory reagent, activator of solvents and raw materials for the chemical industry
Small but significant amounts of adipic acid are used as a food ingredient as a flavoring, although it also helps in gelling. Excellent in food .
Health effects
Adipic acid, like most carboxylic acids, is a mild irritant to the skin , eyes, and respiratory tract. While mildly toxic, with an LD50 of 3,600 mg / kg by oral ingestion, for rats . May form combustible dust concentrations in air.
Environmental toxicity
When released to the ground , this material can biodegrade to a moderate dimension. When released into the soil , this material is not expected to evaporate significantly. When released into the water, this material is expected to rapidly biodegrade. When released into the air, this material can be moderately biodegraded by reaction with photochemically produced hydroxyl radicals.
