Conversion of bis(trichloromethyl) carbonate to phosgene and reactivity of triphosgene, diphosgene, and phosgene with methanol(1).

Triphosgene was decomposed quantitatively to phosgene by chloride ion. The reaction course was monitored by IR spectroscopy (React-IR), showing that diphosgene was an intermediate. The methanolysis of triphosgene in deuterated chloroform, monitored by proton NMR spectroscopy, gave methyl chloroformate and methyl 1,1, 1-trichloromethyl carbonate in about a 1:1 ratio, as primary products.

X-ray structures and anionotropic rearrangements of Di-tert-butyl-substituted thiiranium and thiirenium ions. A structure-reactivity relationship.

The X-ray structures of c-2,t-3-di-tert-butyl-r-1-methylthiiranium 8 BF(4)(-), t-2,t-3-di-tert-butyl-r-1-methylthiiranium ion 10 BF(4)(-), and 2,3-di-tert-butyl-1-methylthiirenium 11 BF(4)(-) have been determined. The DeltaG()(298) values for the rearrangements from the cis and the trans tert-butyl groups of 8 SbCl(6)(-) to thietanium ion (two intramolecular S(N)2 displacements) and for the rearrangement of 11 SbCl(6)(-) to thietium ion (an intramolecular S(N)2-Vin displacement) are linearly correlated with the strengths of the C-S breaking bonds, suggesting that the two mechanisms are, in the absence of steric hindrance, uniquely governed by the nucleofugality of the sulfonium leaving group.

[Cerebral protection in surgery of the carotid arteries].

The authors, starting from the larger and larger spreading of the carotid surgery, consider the risks of cerebral ischemia involved and the measures suitable to reduce its incidence. So, they analyse the measures, both pharmacologic and mechanical, which, before, during and after operation, may contribute in reducing the possibility of incidence of such a deprecable complication.