THE literature contains references to the instability of sulphonic esters of benzyl and ally1 alcohol and to the relatively unstable esters of some secondary alcoho1s.l In all these decompositions, the free sulphonic acid is formed together with dark resin: from the esters of some secondary alcohols, formation of olefin has been reported.2To aid another investigation, cyclohexyl, cyclopentyl, and 1 : 3 : 3-trimethylbutyl toluene-+-sulphonate were examined. The pure esters can be preserved for months in the absence of moisture or acid : less pure samples decompose after a week or so with the formation of toluene-+-sulphonic acid and olefins and their polymers. The decomposition is hastened by heat and by addition of free sulphonic acid. At 120" the cyclohexyl ester decomposes completely in 1 hr. if sulphonic acid is added. The neutral product is resolved by distillation into well-defined portions corresponding to the C,, and the C,, hydrocarbon and a considerable amount of higher polymers. The C,, fraction contains a high proportion of saturated hydrocarbons : dicyclohexyl is present, and hydrocarbons which could not be dehydrogenated completely to aromatic hydrocarbons and presumably contain methylcyclopentane rings. The C,, fraction was obviously a mixture and contained unsaturated hydrocarbons. Decomposition of the cyclopentyl ester gave similar products, The third ester gave a dimer which was largely unsaturated and still retained in part the original structure of the alcohol; trimers and polymers were also formed.Exflerimental.-Preflaration of cyclohexyl toluene-p-sulphonate. Attention to detail is necessary for the best yield : in particular the pyridine should be dry and freshly distilled over barium oxide; the sulphonyl chloride also should be dry and free from toluene-p-sulphonic acid and from hydrochloric acid. cycloHexano1 (180 g., 1.8 moles) and pyridine (650 c.c.) were mixed in a 1.6-1. round-bottomed three-necked flask fitted with a Hirschberg stirrer driven by a heavy-duty motor. At -8' toluene-p-sulphonyl chloride (323 g., 1.7 moles) was added in three equal portions to the stirred solution, sufficient time being allowed to elapse between each addition to keep the temperature below -3". The mixture became deep pink; i t was stirred for 4 hr. after the chloride had been added and the temperature allowed to rise to 0'. The w-hole was stored a t 0" overnight. The mixture, which had become solid, was removed with cold water (1500 c.c.) and treated with concentrated hydrochloric acid (1 1.). The crude ester was a golden-yellow oil which solidified (410 g., average of 15 preparations).Purification is best effected by dissolving the crude ester in the minimum amount of light petroleum (b. p. 40-60°), separating the clear upper layer, and chilling it while stirring. cycZo-Hexyl toluene-p-sulphonate separates as a white powder, m. p. 45-5-46" (350 g.) (Tipson et aZ.3 give m. p. 45-46').cycZoHexy1 toluene-p-sulphonate (350 g.) and toluene-fi-sulphonic acid (50 g.) were heated with occasional shaking a t 120'...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.