Cyclic Polyolefins. VII. Structure of the Eight-membered Cyclic Dimer of Chloroprene¹

Dimerization Products of Chloroprene are Background Contaminants Emitted from ALTEF (Polyvinylidene Difhioride) Gas Sampling Bags

“…Nevertheless, we are confident with the identification because of their distinctive mass spectra and separation by their boiling points as well as the identical set of the dimerization products II, III and VI reported in the previous studies. [24][25][26] These dimers were also detected in the chloroprene standard analyzed (Fig. 1b), and their mass spectra and the GC retention times matched those detected in the bags.…”

“…1a). Since the chloroprene dimers are not commercially available, their identities were deduced from information about their retention times and boiling points with reference to the literature 24,25,31 as well as from a manual interpretation of the mass spectra in aid of the NIST11 mass spectral library. Nevertheless, we are confident with the identification because of their distinctive mass spectra and separation by their boiling points as well as the identical set of the dimerization products II, III and VI reported in the previous studies.…”

“…The dimers II and III are formed from the monomer chloroprene via the Diels-Alder reaction. 24,25 The compound VI has been proposed to be formed from 1,2-dichloro-1,2-divinylcyclobutane (V), a less stable dimer of chloroprene whose structure is shown in Table 1, via the Cope rearrangement. 37 The compounds II, III and VI have been reported to be as dimerization products of chloroprene.…”

“…The four chloroprene dimerization products were identified by comparison with published literature [24][25][26] for the relative retention times and mass spectra and by manual interpretation in aid of the NIST11 mass spectral library. Additionally, they were confirmed by comparison with those of the purchased chloroprene standard solution where the dimers were detected.…”

Homologation of ketones into carboxylic acids

“…Re-oxidation to the radical was achieved with PbO 2 and finally hydrolysis of the ester gave the desired spin probe 85 in 68%. Tabushi et al has used this strategy to functionalize a bicyclo[3.3.0]-octane,85 Scheme 19.Cyanohydrin 87 was prepared from the sodium bisulfite adduct of 86 with potassium cyanide by Cope's procedure 83. Dehydration of cyanohydrin 87 86 produced two products 88a and 88b in a 45:55 ratio as determined by NMR or vapor phase chromatography.…”