Hydrogen chloride with epoxides

Further dechlorination may occur with the formation of substituted diphenyhnethanes. If enough aluminum metal is present, the Friedel-Crafts reactions involved may generate considerable heat and smoke and substantial amounts of hydrogen chloride, which reacts with more aluminum metal, rapidly forming AlCl. The addition of an epoxide inhibits the initiation of this reaction by consuming HCl. Alkali, alkaline-earth, magnesium, and zinc metals also present a potential reactivity hazard with chlorinated solvents such as methylene chloride. 

The manufacture and uses of oxiranes are reviewed in (B-80MI50500, B-80MI50501). The industrially most important oxiranes are oxirane itself (ethylene oxide), which is made by catalyzed air-oxidation of ethylene (cf. Section 5.05.4.2.2(f)), and methyloxirane (propylene oxide), which is made by /3-elimination of hydrogen chloride from propene-derived 1-chloro-2-propanol (cf. Section 5.05.4.2.1) and by epoxidation of propene with 1-phenylethyl hydroperoxide cf. Section 5.05.4.2.2(f)) (79MI50501). 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladimn chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, - by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazone with sodium hydride. ... 

The furan (450) is also formed on photolysis of 1,3-diphenylindenone epoxide (449) in ethanol. Hydrolysis of the epoxide (449) in acetic acid with hydrogen chloride was also... 

Although the above authors did not advance a detailed mechanism, it appears probable that nitrosyl cation can in effeot function us a proton, forming an oxonium-type intermediate (Eq. 940). Attack hv Cl ion is thereby facilitated and occurs with Walden inversion, us in the cleavage of epoxides with hydrogen chloride itself. 

In the event, iodolactonization of the carboxylate salt derived from the ester 458 afforded 459, and subsequent warming of the iodo lactone 459 with aqueous alkali generated an intermediate epoxy acid salt, which suffered sequential nucleophilic opening of the epoxide moiety followed by relactonization on treatment with methanol and boron trifluoride to deliver the methoxy lactone 460. Saponification of the lactone function in 460 followed by esterification of the resulting carboxylate salt with p-bromophenacylbromide in DMF and subsequent mesylation with methanesulfonyl chloride in pyridine provided 461. The diazoketone 462 was prepared from 461 by careful saponification of the ester moiety using powdered potassium hydroxide in THF followed by reaction with thionyl chloride and then excess diazomethane. Completion of the D ring by cyclization of 462 to the keto lactam 463 occurred spontaneously on treatment of 462 with dry hydrogen chloride. 

Epoxides can stabilize polymers either by reacting with hydrogen chloride forming chlorohydrin or by inhibiting the radical decomposition... 

The trienone (74), either by reaction with diazomethane and pyrolysis of the derived pyrazoline or by treatment with dimethylsulphoxonium methylide anion, yielded28 the 1 a,2 -methylene derivative (75). Epoxidation followed by the action of hydrogen chloride gave (77). The methylene bridge was re-formed by the reaction of collidine, the product being (76). Halogenated steroids of use in determining the metabolic fate of 16-chloro-oestrone methyl ethers and of chlormadinone acetate have been synthesized.29... 

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