Carbonyl chloride fluoride availability

Carbonyl chloride fluoride does not associate in the gas phase [1885], and possesses the expected planar Cj structure. The results of the published structural studies are summarized in Table 16.8 the most reliable determination is the result of the combined electron diffraction and microwave spectroscopic study [1531]. Remarkably, prior to these data being published, the fully optimized geometry calculated by ab initio molecular orbital methods [1532] was demonstrated (correctly) to be far superior to the best experimental results available (see Table 16.8). Rather unfortunately, a more recent ab initio study [2176a] performed rather... 

The commercial availability of carbonyl chloride fluoride is, to say the least, variable appearing on suppliers lists e.g. Fluorochem and Ozark-Mahoning) in some years, and not in others. When available, this material has a price that is disproportionately high relative to phosgene and carbonyl difluoride, reflecting the speciality nature of the compound and the absence of any bulk production. 

Acid anhydrides as activated derivatives of carboxylic acids have found little attention for the preparation of acid halides. Their use can be justified if they are obtained from other sources than from carboxylic acids, e.g. phthalic anhydride from the oxidation of naphthalene or o-xylene. It is, therefore, no surprise that there exist patents to convert phthalic anhydride to phthalic acid dichloride with carbonyl dichloride in the presence of catalysts. " However, there are some methods available thus a,a-di-chloromethyl methyl ether will convert acid anhydrides to acid chlorides and brenzcatechyl phosphorus tribromide will also achieve this transformation. Fluorides may be prepared similarly with the pyridine/HF mixture of 01ah. °... 

The synthesis of alkylidene and allylidene cyclopropanes reported in this section takes advantage of the availability 77 78,81 a-82) of l-(l-silyl) cyclopropyl carbinols from a-lithio cyclopropylsilanes and carbonyl compounds. It, however, suffers from the sometimes modest yields obtained when ketones are involved (Schemes 21 a, 47) in the Peterson olefination reaction 77,78,81a) (Schemes 21, 48). This reaction seems much more difficult to achieve than when straight-chain analogs are involved and resembles the cases of allenes 1211 and chlorocyclopropenes120) reported by Chan. For example, thionyl chloride alone is not suitable for that purpose 77,136) but further addition of tetra-n-butylammonium fluoride (20 °C, 15 hrs) leads to the formation of undecylidene cyclopropane77,136 in 46% yield from the corresponding l-(l-silyl)cyclopropyl... 

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