Tertiary carbon atom, peroxidation products

A low yield of octanes was formed when ethylene was heated with 2,2-dimethylbutane (i.e., neohexane) in the presence of di-t-butyl peroxide and 20% hydrochloric acid (Expt. 12). The low conversion was probably due to the difficulty in abstracting a hydrogen atom attached to a neopentyl carbon atom (i.e., a secondary carbon atom attached to the tertiary carbon atom of a t-butyl group). The principal octane (about 75% of the octane product) was 2,2,3-trimethylpentane formed by ethylation at the secondary carbon atcxn 2,2-dimethylhexane formed by condensation at a primary carbon atom (the neohexyl carbon atom) was obtained in... 

The peroxide-induced ethylation of isobutyl chloride in the presence of 19% hydrochloric acid involved monoethylation at all of the carbon atoms in the molecule (Expt. 23). As might be expected, the chief product was l-chloro-2,2-dimethylbutane, produced via abstraction of the hydrogen atom attached to the tertiary carbon atom. Also formed were l-chloro-2-methylpentane (ethylation at a methyl group) and 3-chloro-2-methylpentane (ethylation at the carbon at< n holding the chlorine atom). Some 1-chlorohexane was also obtained in this case, its formation was undoubtedly due to telomerization of the ethylene with hydrogen chloride rather than by a reaction involving the isobutyl chloride. 

The product formed in largest amount by the hydrochloric acid-promoted and peroxide-induced reaction of isopentyl chloride with ethylene was also that formed by alkylation at the tertiary carbon atom, namely 1-chloro-3,3-dimethylpentane (Ig.) (Expt. 25). The remaining constituents of the reaction product were all obtained in very minor amount and were all alkyl chlorides. Among these were 4-chloro-2-methylhexane (y), 1-chlorohexane (formed by telomerization) and some chlorononanes including 5-chloro-3,3-dimethyl-heptane (3 ) formed by ethylation of 12, 4-chloro-2-methyloctane (15) and l-chloro-3-methyloctane (IT). ... 

It may be concluded that primary alkyl chlorides undergo peroxide-induced, hydrogen chloride-promoted, alkylation with ethylene to yield products formed by alkylation at a tertiary carbon atom, at a penultimate secondary carbon atom, or at a primary carbon atom holding a chlorine atom. In the absence of hydrochloric acid, n-butyl chloride underwent little peroxide-induced reaction with ethylene presumably because hydrogen chloride is necessary for propagating the reaction chain via abstraction of hydrogen from the hydrogen chloride to produce the ethylated product and a chlorine atom which maintains the chain by abstraction from the alkyl chloride. 

Ethers. Low yields of several compounds were obtained when ethvl ether was heated at 130-140 under ethylene pressure in the presence of di-t-butyl peroxide and hydrochloric acid (Expt. 26, Table V). Ethylation took place in the normal fashion to yield ethyl sec-butyl ether by monoethylation together with at least three ethers having eight carbon atoms di-sec-butyl ether, (ethylation at both secondary carbon atoms of the ethyl ether), ethyl 1-methyl-l-ethylpropyl ether (ethylation at the tertiary carbon atom of the primary product) and ethyl-1-methylpentyl ether formed by telomerization of the primary radical with two molecules of ethylene). Some Cio ethers were also formed. 

As with the poly (dienes), the polyolefins peroxidise to biodegradable products through the intermediate unstable hydroperoxides. Scheme 3 illustrates this process for poly(ethene), (PE). Poly(propene) (PP) peroxidises much more rapidly than PE due to the tertiary carbon atom (Scheme 2) and the higher proportion of vicinal hydroperoxides formed [6,9]. In-chain hydroperoxide formation continues steadily in all the polyolefins provided oxygen is available and the rate of biodegradation correlates with the rate of abiotic peroxidation. 

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