Adipic acid has been incorporated into controlled-release tablets to obtain a pH-independent release for both weakly basic and weakly acidic drugs. It has also been incorporated into polymeric coatings of hydrophilic monolithic systems to modulate the pH, resulting in zero-order release of a hydrophilic drug.
In foods, small but significant amounts of adipic acid are used as a food ingredient as a flavorant and gelling aid. It is used in some calcium carbonate antacids to make them tart.
Historically, adipic acid was prepared from various fats by oxidation. Currently, adipic acid is made from a mixture of cyclohexanone and cyclohexanol called “KA oil,” the abbreviation of “ketone-alcohol oil.” The KA oil is oxidized using nitric acid to produce adipic acid, via a multistep pathway. Early in the reaction, cyclohexane is converted to the ketone, which releases the nitrous acid.
Adipic acid is an organic compound with the formula (CH2)4(COOH)2. It is the most important of the dicarboxylic acids from the industrial perspective. Approximately 2.5 billion kilograms of this white crystalline powder are produced annually, predominantly as a precursor for the production of nylon 66. Adipic acid rarely occurs in nature.
The majority of the 2.5 billion kg of adipic acid produced annually is used as a monomer for the production of nylon by a polycondensation reaction with hexamethylene diamine forming 6,6-nylon. Other applications include some Polyurethanes. Esters of Adipic Acid, such as DOA (Di-2-Ethylhexyl Adipate) are used as plasticizers for PolyVinyl Chloride (PVC) resins.
Almost 90 percent of adipic acid produced is used in the production of nylon 66. The nylon, which has a protein-like structure, is further processed into fibers for applications in carpeting, automobile tire cord, and clothing. Adipic acid is also used to manufacture plasticizers and lubricant components.
TCC’s Adipic Acid is a mildly toxic, white, crystalline compound. The C6 straight-chain dicarboxylic acid is slightly soluble in water and soluble in alcohol and acetone. Nearly all commercial adipic acid is produced from cyclohexane.
Adipic acid, HOOC(CH2)4COOH, is a white crystalline solid used primarily in the manufacture of nylon-6,6 polyamide. In industry, adipic acid is mainly produced by oxidation of cyclohexane with air and nitric acidfollowing a homogeneous two-step route. However, this process leads to the formation of nitrous oxide, a greenhouse gas that has to be decomposed. The aim of this study was the development of a clean technology at pilot scale in order to obtain and recover pure adipic acid, and the evaluation of its industrial practicability. Adipic acid was synthesized from cyclohexene and hydrogen peroxide in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant. The non-polluting catalyst sodium tungstate, which contains no heavy metal, was used and the reaction conducted under mild conditions (85 C, 8 h). Yields of up to 81% were reached at the 0.14 L scale. However at the end of the reaction the catalyst and the surfactant must be separated and recycled for subsequent cycles. The reuse of the reaction media enabled the conversion to be increased up to 92% but a loss of surfactant and/or catalyst through the cycles progressively reduced the yields. Yields at the bench scale (1.4 L) increased during the two first cycles and then decreased to conversions of between 60% and 70%. Globally the yield is a little lower at bench scale. The results obtained show that the synthesis of adipic acid by a heterogeneous one-step oxidation of cyclohexene in the presence of hydrogen peroxide is an attractive route for developing a future green industrial process.
APPLICATION OF GREEN CHEMISTRY TO SOLVE A PROBLEM
a THREAT CAN BE ELIMINATED BY APPLYING GREEN CHEMISTRY APPLYING SAFE RAW MATERIALS FOR PRODUCTION PROCESSES
aDIPIC ACID- PRODUCTION OF NYLON POLYURETHANES,LUBRICANTS AND PLASTICISERS
BENZENE- A STANDARD(TOXIC) SUBSTRATE NEEDED FOR THE PRODUCTION OF THE ADIPIC ACID
CHEMISTS HAVE DEVELOPED GREEN SYNTHESIS OF ADIPIC ACID BY USING A LESS TOXIC SUBSTRATE.
Quesada-Peñate, Isariebel and Lesage, Geoffroy and Cognet, Patrick and Poux, Martine Clean synthesis of adipic acid from cyclohexene in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant: From the laboratory to bench scale. (2012) Chemical Engineering Journal, vol. 200-202. pp. 357-364. ISSN 1385-8947
Qi, P.; Chen, H.-L.; Nguyen, H. T. H.; Lin, C.-C.; Miller, S. A. “Synthesis of Biorenewable and Water-Degradable Polylactam Esters from Itaconic Acid” Green Chem.,2016,18,4170-4175.
Back Cover Graphic for Green Chemistry, 2016, Issue 15
PRODUCTION OF ACID(BY GLUCOSE CONVERTED INTO ADIPTIC ACID BY AN ENZYME DISCOVERED IN BACTERIA) GUARDS THE WORKERS AND THE ENVIRONMENT FROM EXPOSURE TO HAZARDOUS CHEMICAL COMPOUNDS
THEREFORE GREEN CHEMISTRY PRINCIPLE 3 IS APPLIED!