Synthesis of Carbynoid Materials by Chemical Dehydrohalogenation of Halogen-Containing Polymers - Polyynes: Synthesis, Properties, and Applications - page 249

Similarly, dehydrochlorination of poly(1,2,3-trichlorobutadiene) should
bring about the formation of the cumulene form of carbyne as it seems to be
predetermined by chemical structure of intermediate polyene, viz. poly(2,3-
dichloro-2-butene-1,4-diylidene) (Scheme 12.3).

SCHEME 12.3

In reality, however, the dehydrochlorination products of these two
poly(trichlorobutadiene)s contain both types of carbon chains owing to
notorious intrinsic defects (in this case these are head-to-head-, 1,2-, and
3,4-links incorporated in the polymer backbone, as well as branching
points), side reactions, and possible isomerization of both original polymers
and final products [3].
More recently, Cataldo reported on chemical dehydrohalogenation of
chlorinated oligoethylene (molecular weight 6000) and paraffin waxes

C 22-30 [15-17], which afforded soluble intermediates and even partially
soluble ultimate products. The chlorine content after chlorination was found
to be 73.7% in oligoethylene wax [16], 70% in chlorinated paraffin wax
[15,17], and 72.7% in chlorinated docosane [16], which is close to that in
poly(vinylidene chloride) (73.14%). The predominant structure of chlori-
nated hydrocarbons was reported to be analogous to that of poly(1,2-
dihaloethylene)s [15,16]. The dehydrochlorination process in this case could

be expected to proceed in the way shown in Scheme 12.1 . However, the

presence of side chains in oligoethylene and in paraffin wax, as well as some
over-chlorination of oligoethylene, and under-chlorination of paraffin wax
and docosane, results in the deviation of the halogen-to-carbon ratio from 1,
which makes exhaustive elimination impossible (Scheme 12.4).

SCHEME 12.4