Conversion into adipic acid

T. Iwahama, K. Syojyo, S. Sakaguchi, and Y. Ishii, Direct conversion of cyclohexane into adipic acid... 

Direct conversion of cyclohexane into adipic acid has been achieved under the Ishii oxidation reaction conditions [34e], The selectivity of adipic acid formation was 73% at 73% conversion in the presence of NHPI and Mn(acac)i at 100 °C for 20 h. The oxidation of other cycloalkanes is presented in Table IX.3 [34e],... 

The epoxidation method developed by Noyori was subsequently applied to the direct formation of dicarboxylic acids from olefins [55], Cyclohexene was oxidized to adipic acid in 93% yield with the tungstate/ammonium bisulfate system and 4 equivalents of hydrogen peroxide. The selectivity problem associated with the Noyori method was circumvented to a certain degree by the improvements introduced by Jacobs and coworkers [56]. Additional amounts of (aminomethyl)phos-phonic acid and Na2W04 were introduced into the standard catalytic mixture, and the pH of the reaction media was adjusted to 4.2-5 with aqueous NaOH. These changes allowed for the formation of epoxides from ot-pinene, 1 -phenyl- 1-cyclohex-ene, and indene, with high levels of conversion and good selectivity (Scheme 6.3). 

The total hydrogenation of benzene derivatives represents an important industrial catalytic transformation, in particular with the conversion of benzene into cyclohexane, a key intermediate in adipic acid synthesis, which is used in the production of Nylon-6,6 (Scheme 1). This reaction is still the most important industrial hydrogenation reaction of monocyclic arenes [1]. 

Similarly, cyclohexane is readily oxidized by cobalt(III) acetate in acetic acid at moderate temperatures.29Sa d In the absence of oxygen at 80°C the main products were 2-acetoxycyclohexanone and cyclohexyl acetate. Cyclohexane was about half as reactive as toluene under these conditions. Oxidation with Co(III) acetate in the presence of oxygen gave adipic acid as the main product. This reaction has been developed into a process for the single-stage oxidation of cyclohexane to adipic acid.296,297 Selectivities of approximately 75% have been claimed at roughly 80% cyclohexane conversion. 

Diselenane (25 R = H), a low-weight polymer (monomeric in solution), is available from 1,4-dibromobutane in two steps first conversion into the 1,4-diselenocyanate (24 R = H), and then treatment of this product with alcoholic potassium hydroxide in the presence of oxygen (Scheme 13) <29JCS1096>. The l,2-diselenane-3,6-dicarboxylic acid (25 R = C02H) can be synthesized in a similar way from meso-2,5-di(selenocyanato)adipic acid <33AK(27)6>. 

United Nigeria Textile (Ltd) UNTL Kaduna is making nylon 6,6 from hexamethylenediamine and adipic acid. One batch is made on every 8-h shift. In each batch equimolar reactants are used and conversion is usually 98.0%. At the end of the run the bulk product is extmded and chopped into pellets. 

Before it will be practical to consider using a microbial catalyst to manufacture adipic acid, significant challenges must be addressed. To improve catalyst stability and increase the percent conversion of D-glucose into product, further development of the microbial catalyst will be needed. The scale of the reaction also requires adjustment from laboratory shake flasks to fermentation tanks, which would then be readily scaled to industrial production. Future efforts will focus on these challenges. 

If a bifunctional compound (e.g., adipic acid) is condensed with a trifunctional one (e.g., glycerol) in a functional group molar ratio of 1 1, then after a certain time the viscous mass changes into an elastic gel. This transition is sufficiently sharp for it to be possible to speak of a gel point. Immediately after passing the gel point, this gel contains a fraction that is insoluble in all solvents plus a soluble fraction. It is thus only partially cross-linked. As the conversion increases, the soluble fraction becomes progressively smaller. 

In the shikimic acid area, the conversion of D-glucose into the industrially important compound adipic acid using mutant enzymes derived from the shikimate pathway has been reported." ... 

In our original work, an E. coli host containing three plasmids was used to catalyze the conversion of glucose into cw,cw-muconic acid under shake flask conditions.Our most recent construct uses a single plasmid and catalyzes the conversion of glucose into c/5,cw-muconic acid under controlled, fed-batch fermenter conditions similar to those employed for microbe-catalyzed synthesis of shikimic acid and quinic acid from glucose. After removal of the biocatalyst, the clarified fermentation broth is treated with activated carbon to remove unidentified molecules in the broth that poison platinum catalysts. The d5,ci5-muconic acid can then be hydrogenated over a platinum-on-carbon catalyst to afford adipic acid in nearly quantitative yield. 

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