Phosgene s. a. under

An ethereal soln. of the startg. enamine and triethylamine added at -20 to -10° to phosgene, the resulting triethylamine hydrochloride removed by filtration, and the filtrate treated dropwise at -20 to -10° with methanol and triethylamine methyl a-phenyl-/ -pyrrolidinoacrylate. Y 78%. - The reaction of enamines with phosgene occurs under mild conditions and provides reactive intermediates for the synthesis of / -ketocarboxylic acid derivs. and heterocyclics. F. e. and reactions s. A. Halleux and H. G. Viehe, Soc. (C) 1970, 881. 

Solid bis(trichloromethyl) carbonate as phosgene equivalent) added under Nj to a stirred soln. of cyclohexanecarboxaldehyde and a little pyridine in carbon tetrachloride at —20 at such a rate that the temp, remained at —10° to —20°, the viscous slurry allowed to warm to room temp, over 90 min, heated to 40° for 1 h, cooled to room temp., and stirred overnight cyclohexyl(chloro)methyl chloroformate. Y 89%. The method is mild, high-yielding, and avoids the use of hazardous phosgene. F.e.s. M.J. Coghlan, B.A. Caley, Tetrahedron Letters 30, 2033-6 (1989). 

The manufacture of crystal violet (1), however, is a special case which does not involve the isolation of the intermediate Michler s ketone (Fig. 3). Thus, phosgene is treated with excess dimethyl aniline in the presence of zinc chloride. Under these conditions, the highly reactive intermediate "ketone dichloride" is formed in good yield this intermediate further condenses with another mole of dimethyl aniline to give the dye. 

Polycarbonates with superior notched impact strength, made by reacting bisphenol A, bis-phenol S and phosgene, were introduced in 1980 (Merlon T). These copolymers have a better impact strength at low temperatures than conventional polycarbonate, with little or no sacrifice in transparency. These co-carbonate polymers are also less notch sensitive and, unlike for the standard bis-phenol A polymer, the notched impact strength is almost independent of specimen thickness. Impact resistance increases with increase in the bis-phenol S component in the polymer feed. Whilst tensile and flexural properties are similar to those of the bis-phenol A polycarbonate, the polyco-carbonates have a slightly lower deflection temperature under load of about 126°C at 1.81 MPa loading. 

The purity of naphthostyryl obtained by this method in a yield of 80% is very high (99, 7%) [78GEP(0)2635693, 78GEP(O)2700649], Under analogous conditions, N-alkyl-substituted naphthostyryls 166 (R = Aik, Y = O) or their thio analogs 166 (R = Aik, Y = S) are obtained from mono-N-alkyl derivatives of a-naphthylamine and phosgene (62SZ... 

Phosgene is an oxidising agent, and iodometric techniques, based upon equation (3.2), have been employed for its determination [425,1148,1255,1357,1604]. The reaction must be carried out under anhydrous conditions (commonly in propanone or methyl ethanoate [1604]), and the iodine determined by conventionai procedures, such as by titration with [S fi 3] Although the usual starch indicator cannot be used in propanone solution, the colour of the generated dliodlne affords a reasonably sharp end-point [1560]. In addition, indications of very smali quantities of phosgene are indicated by the reddish-yellow colour of the liberated diiodine, so that the method can be applied for the trace determination of the gas [1560],... 

Phosgene was detected, by g.c.-m.s. and n.m.r. spectroscopy, in a commercial solvent mixture of trichloroethene and tetrachloroethene (80 20) [1254]. Such contamination is likely to arise as a result of photochemical decomposition. The primary product of the oxidation of trichloroethene under ultraviolet radiation is trichloroepoxyethane cf. the thermal decomposition product, structure (3.4), which rearranges to dichloroethanoyl chloride and chloral. Secondary decomposition of one of these compounds occurs to give CO, COj, HCl and COCI2 [ICI55]. 

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