Dehydrochlorinative trimerization

In borazine compounds having branched alkyl groups (other than t-butyl) at the N-atoms, a stepwise substitution of the (B)—H atoms in Grignard alkylation 84> is observed rather than the statistical substitution which occurs on alkylation of N-methylborazines with n-alkyl Grignard reagents 34>. It has been reported 49-85> that base dehydrochlorination of isobutylammonium trichlorophenylborate as well as that of isobutyl-amine-dichlorophenylborane results in a mixture of the trimeric and tetrameric N-isobutyl-B-phenylborazines [Eq. (20)]. 

The trimer of 1-piperidine, best prepared by dehydrochlorination of N-chloropiperidine, has been known for some time. 1-Pyrroline also appears to exist largely as the trimer. Both undergo Mannich reactions with electron-rich heterocycles. Indole reacts with 1-piperidine in a citrate buffer to afford 3-(2-piperidyl)indole in 40-55% yield (equation 45). ° The iV-methylpiperidyl analog has also been... 

Pyrolysis GC has been used in the determination of compositional analysis and microstructure of chlorinated polyethylene (CPE). This method utilized specific aromatic compounds which were formed through dehydrochlorination of trimers after pyrolysis of CPE polymers at elevated temperatures. The composition and microstructure calculation was based on the difference between the levels of ethylene and vinyl chloride trimers formed [19-22]. 

The unique phenomenon in the pyrolysis of vinylidene chloride/vinyl chloride copolymer is the trimer formation. Under pyrolysis conditions, the polymer will directly undergo the thermal dehydrochlorination to form a conjugated polyene [205]. The polymer will then unzip, followed by a radical cyclisation to form benzene, chlorobenzene, dichlorobenzene, and trichlorobenzene. The mechanism can be expressed as ... 

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