Cyclohexyl chloride

By using a lOOX excess of the metal (less than lOO for experiments on a large scale) one can save much time. Some Grignard reactions, especially those with tertiary alkyl chlorides and cyclohexyl chloride, are not easily started and it seemed desirable, therefore, to inform the user of this book about our experiences. 

For substituted cyclohexanes, the slow-exchange condition is met at temperatures below about —50 C. Table 3.5 presents data for the half-life for conformational equilibration of cyclohexyl chloride as a function of temperature. From these data, it can be seen that conformationally pure solutions of equatorial cyclohexyl chloride could be maintained at low temperature. This has been accomplished experimentally. Crystallization of cyclohexyl chloride at low temperature affords crystals containing only the... 

Cyclohexyl bromide, for exfflnple, is converted to cyclohexene by sodium ethoxide in ethanol over 60 times faster than cyclohexyl chloride. Iodide is the best leaving group in a dehydrohalogenation reaction, fluoride the poorest. Fluoride is such a poor leaving group that alkyl fluorides are rarely used as starting materials in the preparation of alkenes. 

Cyclohexyl chloride, 6, 24 Cyclohexylmagnesium bromide, 6, 20 Cyclohexylmagnesium chloride, 6, 24 3 Cyclohfxvi Propinf-i, 6, 26 Cyclopentanone, 5, 37 l Cystine, 5, 39... 

Secondary alcohols such as cyclohexanol or 2-butanol also react on heating for 20-120 min at 80 °C with TCS 14 in the presence of BiCl3 to give the chloro compounds cyclohexyl chloride 784 and 2-chlorobutane in 93 and 90% yield, respectively, HCl, and HMDSO 7 [11, 12]. Benzyl alcohol is transformed likewise by Me3SiCl 14 after 120 min. at 80 °C into benzyl chloride in quantitative yield. Analogously, esters such as 2-acetoxypropane 785 are also converted by TCS 14 in 100% yield into chloro compounds such as 786 and trimethylsilyl acetate 142. The yS-lactone 787 gives rise to 788... 

Finally, reaction of primary, secondary, or tertiary alcohols 11 with Me3SiCl 14 in the presence of equivalent amounts of DMSO leads via 789 and 790 to the chloro compounds 791 [13]. n-Pentanol, benzyl alcohol, yS-phenylefhanol or tert-butanol are readily converted, after 10 min reaction time, into their chloro compounds, in 89-95% yield, yet cyclohexanol affords after reflux for 4 h cyclohexyl chloride 784 in only 6% yield [13] (Scheme 6.5). 1,4-Butanediol is cyclized to tetrahydrofuran (THF) [13a], whereas other primary alcohols are converted in 90-95% yield into formaldehyde acetals on heating with TCS 14 and DMSO in benzene [13b] (cf also the preparation of formaldehyde di(n-butyl)acetal 1280 in Section 8.2.1). 

Phenylnaphthalene has been prepared by the reaction of a-halonaphthalenes with mercury diphenyl3 6 or with benzene in the presence of aluminum chloride,6 and by means of the Gri-gnard synthesis, starting with either bromobenzene, cyclohexyl chloride, and a-tetralone 7 or with a-bromonaphthalene and cyclohexanone.6 8 9 Dehydrogenation of the reduced naphthalene has been accomplished by the use of sulfur,6 bromine,8 platinum black, or selenium.7 The formation of the hydrocar-... 

Cyclohexyl chloride, c91 Cyclohexyl ketone, c366 Cyclohexyl mercaptan, c364 Cyclohexylmethane, m202 Cyclohexylmethyl bromide, b367... 

Scheme 123 Reduction of cyclohexyl chloride to cyclohexyl radicals by rhodium (0).

Constant-potential electrolysis of the [Rh(dppe)2]Cl in an MeCN-Bu4NCl04-(Hg) system gives RhH(dppe)2 (325) in ca. 90% yield. When cyclohexyl chloride (334) is added to the [Rh(dppe)2] (332) electrolysis solution, the radical intermediate (335) together with Cl is produced as shown in Scheme (123) [456]. The cyclohexyl radical (335) generated in this manner has several channels for product formation. 

I) the dipole moment of chlorobenzene Is lower than that of cyclohexyl chloride (ii) alkyl halides, though polar, are Immiscible with water ... 

Halogenation reactions of alkanes provide good examples of radical processes, and may also be used to illustrate the steps constituting a radical chain reaction. Alkanes react with chlorine in the presence of light to give alkyl chlorides, e.g. for cyclohexane the product is cyclohexyl chloride. 

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