Rubber hydrochlorination

Chlorination and hydrochlorination of natural rubber are industrial processes carried out on solutions of uncrosslinked rubber in chlorinated solvents [Allen, 1972 Ceresa, 1978 ... 

Subramaniam, 1988]. Hydrochlorination, usually carried out at about 10°C, proceeds by electrophilic addition to give the Markownikoff product with chlorine on the tertiary carbon (Eq. 9-33) [Golub and Heller, 1964 Tran and Prud homme, 1977]. Some cyclization of the intermediate carbocation (XXVI) also takes place (Sec. 9-7). The product, referred to as rubber hydrochloride, has low permeability to water vapor and is resistant to many aqueous solutions (hut not bases or oxidizing acids). Applications include packaging film laminates with metal foils, paper, and cellulose films, although it has been largely replaced by cheaper packaging materials such as polyethylene. 

Use Production of vinyl chloride from acetylene and alkyl chlorides from olefins, hydrochlorination (see rubber hydrochloride), polymerization, isomerization, alkylation, and nitration reactions. 

Synthetic polyisoprene rubbers were found by Harries during 1910 [19], to be successfully hydrochlorinated. These synthetic polyisoprenes resemble natural rubber, which is also a polymer of isoprene which occurs naturally and therefore hydrogen chloride is rapidly added when the rubber is exposed to it thus forming a protective film of chlorinated rubber or hydrogen chloride. Polybutadiene, and butadiene acrylonitrile rubbers do not add hydrogen chloride from hydrochloric acid. 

Hydrochlorination of natural rubber is often accompanied by cyclization ... 

Hydrochlorination of rubber in solution causes a different kind of double-bond shift ... 

Characteristic examples of industrial fast chemical reactions are the electrophilic polymerisation of isobutylene [7], its copolymerisation with isoprene [10], chlorination of olefins [17] and butyl rubber [18], ethylene hydrochlorination [17], sulfation of olefins [19], neutralisation of acidic and basic media [20], isobutene alkylation (production of benzines) [21-23], and so on. These examples of fast liquid-phase reactions and a variety of such processes assume a formal approach for their calculation and modelling, based on material and heat balance in the industrial implementation of respective products. It is a priori acknowledged that is not difficult to achieve an isothermic mode for fast chemical exothermic processes if you are aware of the process behaviour and can control it. 

The addition of hydrogen chloride to unsaturated elastomers has also received considerable attention. Extensive work has been done on the hydrochlorination of Hevea [poly(cis-l,4-l,4-isoprene)] and Balata [poly(rrans-l,4-isoprene)] rubbers since 1940 [36,37]. Both cis-1,4 and tram cis-1,4-polyisoprenes readily add hydrogen chloride following Markovnikov s rules with only a small amount of cyclization. 

Examples include the polyamides synthesized from fatty adds obtained via ozoanization of vegetable oils, chlorinated or hydrochlorinated natural rubber to obtain plastic materials, and the various modifications of cellulose or chitin. 

Natural rubber was chlorinated by G.A. Englehard and H.H. Day in 1859, hydrochlorinated in 1881 and isomerized by Leonhardi in 1881 (12). However, these rubber derivatives were not commercialized until the early part of the twentieth century. Likewise, polyvinyl chloride was described by Regnault in 1838, by Meyer in 1866 and by Baumann in 1872 (13,14) but was not commercialized until the 1930 s. It is of interest to note that Baumann considered the solid polymer to be an isomer of vinyl chloride. 

The hydrochlorination of natural rubber is a straightforward addition reaction which proceeds according to Markownikoff s rule ... 

Hydrochlorination of natural rubber usually yields a polymer with slightly less than the theoretical chlorine content for complete reaction (e.g. 33 5 cf. 33-9%). NMR studies (Golub and Heller, 1964) have established that some cyclization occurs during hydrohalogenation and this can account for the discrepancy. 

Hydrochlorination of rubber Production of vinyl and alkyl chlorides... 

Hydrochlorinated rubber Poly(imino( 1-oxohexamethylene)) (nylon 6) Poly(iminoadipoyliminohexamethylene) (nylon 6,6) Poly(iminoadipoylimino tetramethylene) (nylon moulding 6,10) oriented fibres... 

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