Trichloromethyl-chloroformate

B. 3-Isocyanatopropanoyl chloride. A 500-ml., two-necked flask is equipped with a thermometer and a reflux condenser protected at its top by a calcium chloride tube. A Teflon-coated magnetic stirring bar, 250 ml. of anhydrous dioxane (Note 12), 12.6 g. (0.1 mole) of finely pulverized 3-aminopropanoic acid hydrochloride (Note 13), and 23.8 g. (14.4ml., 0.12mole) of trichloromethyl chloroformate (Note 14) are placed in the flask in the order specified. The mixture is stirred and heated at 55-60°. After ca. 5 hours, the solid has completely dissolved, leaving a clear solution. The heating is discontinued after a total of 7 hours (Note 15), and the solvent is removed under reduced pressure. The residual oil is distilled rapidly under reduced pressure and a distillate amounting to 11.2-12.4 g. (84-93%) is collected at 75-85° (20 mm.) (Note 16). Redistillation affords 10.5-11.8 g. (79-88%) of 3-isocyanatopropanoyl chloride as a colorless liquid, b.p. 92-94° (25 mm.) (Note 17). 

Vapors of all of the polychlorinated methyl chloroformates are toxic. Trichloromethyl chloroformate has a phosgene-like odor and is known to decompose to phosgene at elevated temperature or on contact with ferric oxide or charcoal. ... 

Although the reaction can be carried out with an equimolar amount of trichloromethyl chloroformate, a longer time (15-20 hours) is required to reach completion, and the yield is reduced somewhat. If a 1.5-2.0-fold excess of trichloromethyl chloroformate is used, the reaction time is decreased to ca. 5 hours and the yield is increased to 90-95%. 

Trichloromethyl chloroformate Formic acid, chloro-, trichloromethyl ester (8) Carbonochloridic acid, trichloromethyl ester (9) (503-38-8)... 

The mechanism of the condensation in Part D probably involves thioformylation of the metallated isocyanoacetate followed by intramolecular 1,1-addition of the tautomeric enethiol to the isonitrile. This thi2izole synthesis is analogous to the formation of oxazoles from acylation of metallated isonitriles with acid chlorides or anhydrides. " Interestingly, ethyl formate does not react with isocyanoacetate under the conditions of this procedure. Ethyl and methyl isocyanoacetate have been prepared in a similar manner by dehydration of the corresponding N-formylglycine esters with phosgene and trichloromethyl chloroformate, respectively. The phosphoryl chloride method described here was provided to the submitters by Professor U. Schollkopf and is based on the procedure of Bohme and Fuchs. The preparation of O-ethyl thioformate in Part C was developed from a report by Ohno, Koi/.uma, and Tsuchihaski. " ... 

TRICHLOROMETHYL CHLOROFORMATE AS A PHOSGENE EQUIVALENT 3-ISOCYANATOPROPANOYL CHLORIDE... 

Caution Trichloromethyl chloroformate is toxic. These reactions should both be carried out in a well-ventilated hood Note 1). 

A. Trichloromethyl chloroformate. A 100-ml., three-necked, round-bottomed Pyrex flask is equipped with a thermometer, a reflux condenser protected at the top with a calcium chloride tube, and a gas-inlet tube with a coarse fritted-glass tip extending almost to the bottom of the flask. In the flask are placed 37.8 g. (0.4 mole) of freshly distilled methyl chloroformate (Note 2) and a Teflon-coated magnetic stirring bar. The flask is illuminated with a 100-W. high-pressure, mercury-vapor lamp (Note 3) which is placed beside... 

Although this reaction can be carried out at higher temperatures, the yields are reduced, probably owing to loss of the volatile methyl chloroformate, b.p. 71°, and/or decomposition of the product. For example, the yields of trichloromethyl chloroformate are ca. 75% and 55% when the chlorination is carried out at 50-55° and 85-90°, respectively. 

The chlorination of methyl chloroformate in sunlight was first reported by Hentschel, but without a detailed description of either the procedure or the results. The first step of the present procedure for the preparation of trichloromethyl chloroformate utilizes an ultraviolet light source and affords a simple and reproducible way to obtain this reagent. Although trichloromethyl chloroformate may also be synthesized by photochemical chlorination of methyl formate,the volatility of methyl formate causes losses during the reaction and increases the hazard of forming an explosive mixture of its vapor and chlorine gas. The preparation of trichloromethyl chloroformate by chlorination of methyl chloroformate in the dark with diacetyl peroxide as initiator has been reported. However, the procedure consists of several steps, and the overall yield is rather low. 

Trichloromethyl chloroformate is useful in synthesis as a substitute for phosgene, which, owing to its high volatility and toxicity, presents a severe hazard in the laboratory. Although trichloromethyl chloroformate is toxic, it is a dense and less volatile liquid, b.p. 128°, d l 1.65, having a vapor pressure of only 10 mm. at 20°. Consequently it is more easily handled in a safe manner than phosgene. 

Trichloromethyl chloroformate has proven effective in the preparation of N-carboxy-a-amino acid anhydrides from amino acids, and various compounds having isocyanate, acid chloride, and chloroformate groups.For example, trichloromethyl chloroformate may be used instead of phosgene in the preparation of 2-tert-butoxycarbonyloxyimino-2-phenylacetonitrile. The use of this reagent is illustrated here by the synthesis of 3-isocyanato-propanoyl chloride from 3-aminopropanoic acid hydrochloride. 

Trichloromethyl chloroformate (diphosgene) is used as a safe substitute for highly toxic phosgene gas. The latter is generated in situ by addition of catalytic amounts of tertiary amines or amides, or active carbon. Diphosgene also disproportionates to 2 equivalents of phosgene on heating above 250°C. 

Bisphenol-AF-derived poly(carbonate) (2) has been synthesized by the two-phase transfer-catalyzed polycondensation of Bisphenol AF (1) with trichloromethyl chloroformate (TCF) in organic-solvent-aqueous-alkaline solution systems with a variety of quaternary ammonium salts at room temperature (Scheme l).6... 

R Katakai, Y Iizuka. An improved rapid method for the synthesis of N-carboxy a-amino acid anhydrides using trichloromethyl chloroformate. (diphosgene). J Org Chem 50, 715, 1985. 

Similar oxidation of alcohols has been carried out with dimethyl sulfoxide and other reagents317 in place of DCC acetic anhydride,318 SOy-pyridine-triethylamine,319 trifluo-roacetic anhydride,320 oxalyl chloride,321 tosyl chloride,322 chlorine,323 bromine,324 AgBF4-Et3N,325 P205-Et3N,326 phenyl dichlorophosphate,327 trichloromethyl chloroformate,328 tri-... 

Per Ger desgn for trichloromethyl-chloroformate (CWA) RPE Rocket Propulsion Establis (Brit)... 

Trichloromethyl-chloroformate has been proposed as a relatively safe phosgene source for small-scale diisocyanate and polyurethane production units. Phosgene is produced upon fragmentation of this compound on a hot iron contact. 

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