Of cyclohexane derive

Among all the isomers as 1 2 dichlorocycio hexane is unique in that the ring flipping process typ ical of cyclohexane derivatives (Section 3 9) converts it to its enantiomer... 

The name naphthenic acid is derived from the early discovery of monobasic carboxyUc acids in petroleum, with these acids being based on a saturated single-ring stmcture. The low molecular weight naphthenic acids contain alkylated cyclopentane carboxyUc acids, with smaller amounts of cyclohexane derivatives occurring. The carboxyl group is usually attached to a side chain rather than direcdy attached to the cycloalkane. The simplest naphthenic acid is cyclopentane acetic acid [1123-00-8] (1, n = 1). 

Contrary to expectations, only an unusually small part of the diene exists in the conjugated form. Furthermore the formation of cyclohexane derivatives is noticeable. Their formation can be explained with the compounds listed on row 4 in Table 9. During the alkylation the monoolefin reacts on one side to LAB, on the other side to oligomers, and, depending on the excess of benzene, in part to the dialkylbenzenes found as byproducts in the so-called heavy alkylate (the residues of the raw alkylbenzene distillation). 

A number of cyclohexane derivatives with tertiary amino substituents, especially dimethylamine, have proven to be opioid analgesics. Tilidine, which was synthesized at the beginning of the 1960s, is one of these compounds. Its trans NMe2/C02Et configuration is important for activity since the corresponding cis-isomer is less potent. 

Cyclohexane. Here again, a comprehensive review of the different methods used to form cyclohexanes in carbohydrate chemistry appeared recently [198]. Only the general strategies developed are given in the following. The formation of cyclohexane derivatives... 

Further reactions that are highly suited to the synthesis of cyclohexane derivatives, such as cycloaddition processes, 1,3-dipolar additions, and Diels-Alder cyclizations, have been used extensively. In the latter set, carbohydrate-based dienes or dienophiles have been employed and, in addition, intramolecular processes have provided highly suitable means of synthesizing complex polycyclic systems. 

Aldose dithioacetals, which are devoid of leaving groups, notably oxygen-bonded functions at C-2, on treatment with strong bases, afford stable C-l carbanions that allow the formation of cyclohexane derivatives when suitable leaving groups are present at C-6. 

The cis-trans isomerism of cyclohexane derivatives (Section 5-1 A) is complicated by conformational isomerism. For example, 4-tert-butylcyclohexyl chloride theoretically could exist in four stereoisomeric chair forms, 1, 2, 3, and 4. 

Determining the Relative Stabilities of Conformations of Cyclohexane Derivatives... 

Draw the two chair conformations of cyclohexane derivatives and determine which is more stable. (Problems 6.21, 6.22, and 6.25)... 

Only one special paper concerning the ring interconversion in solution of cyclohexane derivatives was published. The ring inversion of cis-1,2-bis(trimethylsilyl)cyclohexane coalesces at 236 K, a values of AG =12.0 kcal/mol was calculated for this dynamic process, somewhat higher than that for cyclohexane (10.3 kcal/mol) (95MI25). 

The X-ray structures of a large number of cyclohexane derivatives were published the conformation of the cyclohexane ring and the conformations of substituents on the saturated six-membered ring are given in Table VII. 

Turova-Polyak and co-workers have carried out extensive studies of naphthene isomerization with AICI3, particularly of the substituted cyclopentanes. The conversion of mono- and disubstituted cyclopentanes to cyclohexanes was reported as an analytical technique for the determination of cyclopentanes in mixture with paraffins (411). Ethyl-cyclopentane at room temperature gave an 18-20% yield of cyclohexane derivatives (412). At 140-145°, an 85% yield of 1,3,5-trimethyl-cyclohexane was obtained. This work was also extended to 1,1-dimethyl-cyclopentane (410), up to 95% of which was converted to methyl-cyclohexane at 115°. Similar conversions of alkylated cyclopentanes were also reported by Shulkin and Plate (375). These researches parallel similar work done in the United States. 

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