1- Methylcyclohexanecarboxylic

In addition to the present method,2 1-amino-1-methylcyclo-hexane has been synthesized by the following procedures Ritter reaction, e.g., with 1-methylcyclohexanol (76%, 67%)3i 4 or 1-methylcyclohexene (35%,) 4 5 Hofmann reaction with 1-methyl-cyclohexanecarboxamide (80% as hydrochloride) 6 reduction of 1-methyl-l-nitrocyclohexane (63%) 6 Schmidt reaction with 1-methylcyclohexanecarboxylic acid (42%).6... 

The enthalpy of fomation of two such species has been measured, namely the cyclopropane and cycloheptane derivatives. The difference between the values for these two species, both as solids, is 238.1 kJmol . Is this difference plausible Consider the difference between the enthalpies of formation of the parent cycloalkanes as solids, 194 kJ mol . The ca 44 kJ mol discrepancy between these two differences seems rather large. However, there are idiosyncracies associated with the enthalpies of formation of compounds with three-membered rings and almost nothing is known at all about the thermochemistry of compounds with seven-membered rings. Rather, we merely note that a seemingly well-defined synthesis of cycloheptyl methyl ketone was shown later to result in a mixture of methyl methylcyclohexyl ketones, and superelectrophilic carbonylation of cycloheptane resulted in the same products as methylcyclohexane, namely esters of 1-methylcyclohexanecarboxylic acid. The difference between the enthalpies of formation of the unsubstituted alicyclic hydrocarbons cycloheptane and methylcyclohexane as solids is 33 kJmol . This alternative structural assignment hereby corrects for most of the above 44 kJ mol discrepancy in the enthalpies of formation of the two oximes. More thermochemical measurements are needed, of oximes and cycloheptanes alike. 

Methylcyclohexanecarboxylic acid can be prepared by car-bonation of the Grignard reagent from 1-chloro-l-methylcyclo-hexane3 or by Friedel-Crafts condensation of 1-chloro-l-methyl-cyclohexane with methyl 2-furancarboxylate followed by saponi-... 

This procedure illustrates a general method of carboxylating saturated hydrocarbons that have a tertiary hydrogen.7 It has been used to convert isopentane to 2,2-dimethylbutanoic acid, 2,3-dimethylbutane to 2,2,3-trimethylbutanoic acid, and methyl-cyclohexane to 1-methylcyclohexanecarboxylic add. 

Another example is the synthesis of 1-methylcyclohexanecarboxylic acid from crude 2-methylcyclohexanol. ... 

Scheme 9.147. A representation of the reaction between the methyl ester of cyclohexanecar-boxylic acid (methyl cyclohexanecarboxylate) with lithium diisopropylamide (LDA) to generate a carbanion on the carbon a- to the carbonyl. The carbanion so formed then acts as a nucleophile toward methyl iodide (CH3I) to yield methyl 1-methylcyclohexanecarboxylate, lithium iodide, and recovered base, diisopropylamine ([(CH3)2CH]2NHj.

Substitution processes focused around the carbonyl group as well as at the carbonyl group are, of course, also possible. Consider the case depicted in item 7 of Table 9.9. As noted immediately above for the intermolecular and intramolecular versions of the Claisen condensation, success depends upon generation of an anion a- to the carbon of the carbonyl. Generation of such anions, particularly at fairly high dilution (where reaction between esters is less likely) with hindered bases, followed by addition of an electrophilic species to the reaction medium, results in overall substitution of the electrophilic species for the proton that was removed. In item 7 of Table 9.9, as shown in Scheme 9.147, the methyl ester of cyclohexanecar-boxylic acid (methyl cyclohexanecarboxylate) does not react with the hindered base (LDA) at the carbon of the carbonyl. Rather, the base removes the proton on the carbon a- to the carbonyl and the carbanion so formed then acts as a nucleophile toward methyl iodide (CH3I). Substitution yields methyl 1-methylcyclohexanecarboxylate, lithium iodide, and recovered base, diisopropylamine [(CH3)2CH]2NH. ... 

How might you use an alkylation reaction to prepare ethyl 1-methylcyclohexanecarboxylate COjEt -CH3... 

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