Mixed 1,4-Dimethylcyclohexanes

Note According to Chevron Phillips Company s (2005) product literature, >99.5 wt % 1,2-dimethylcyclohexane (mixed stereoisomers) contains o-xylene at a maximum concentration of 300 ppm. 

Ammoxidation is also used for the manufacture of isophthalonitrile from m-xylene. The catalysts claimed in the patents are mixed oxides, e.g., of Mo, V, and Sb. The dinitrile is hydrogenated to m-xylylene diamine and m-diamino-dimethylcyclohexane, used for the production of the corresponding diisocyanates that are less toxic than toluene diisocyanate TDL A different use is for the production of tetrachloroisophthalonitrile, a potent fungicide. 

Knoevenagel condensation of aldehydes with malononitrile under mechanochemi-cal mixing in the presence of MgO resulted in adducts of general structure 138 (Scheme 27), which were further treated with either ethylacetoacetate or 5,5-dimethylcyclohexane-l,3-dione to provide products 139 and 140 [63]. The transformation of 138 and 139 or 140 proceeded via a Michael-type nucleophilic addition of the enolizable ketoester or dione, followed by intramolecular cyclization. 

The various factors affecting the entropies of mixing and rotation of the dimethylcyclohexanes are collected in Table 1. For computation of equilibria in such a complex system it is convenient to define an equilibrium constant, as being the ratio of two isomers that differ by only one, gauche interaction. Then for a pair of isomers that differ in energy by n interactions,... 

A soln. of 5,5-dimethylcyclohexane-l,3-dione in methanol mixed with an aq. soln. of cupric bromide and KBr, stored 65 hrs. at room temp. 2-bromo-5,5-dimethylcyclohexane-l,3-dione. Y 85%.—KI serves to keep the resulting cuprous bromide in soln. F. e. s. A. W. Fort, J. Org. Chem. 26, 765 (1961) steroid derivatives cf. E. R. Glazier, J. Org. Chem. 27, 2937 (1962). 

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