Phosgene, solution of in toluene

A solution of 2-amino-4-fluorobenzoic acid (62 g) in aqueous sodium carbonate (44 g sodium carbonate in 1.6 liters water) was stirred and treated dropwise with a solution of phosgene (120 g) in toluene (500 ml) during 1.5 hours. The resulting suspension was stirred at room temperature for 24 hours. The solid product was collected by filtration, washed with water and dried to give 7-fluoro-l,2-dihydro-3,l(4H)-benzoxazine-2,4-dione melting point 217-219°C. 

Phosgene is readily and cheaply available, in cylinders, or as a solution in toluene (usually 12.5 or 20 % w/w), from commercial suppliers, so that it is rarely necessary to prepare the material in the laboratory. For the preparation of small quantities of phosgene solution of alternative concentrations, or in other solvents, the following procedure may be used, based upon the reaction of tetrachloromethane with sulfuric acid ... 

Nitrophenyl isocyanate has been prepared by heating -nitrophenyl carbamyl chloride. The latter has been obtained by the action of phosgene on -nitroaniline in benzene-toluene solutions, and by the action of phosphorus pentachloride on methyl jii-nitrophenylcarbamate. The preparation given above is based upon recent publications of the authors. ... 

A stirred solution of 40 g (0.41 m) of phosgene in 150 ml of toluene Is held at 25°C with a cooling bath while a mixtura of 25.2 g (0.105 m) of 3.amino-4-benzyloxyacetophenone and 220 ml of toluena are added slowly. The mixture is heated to reflux and continued for 30 minutes. Nitrogen is passed through the mixture and then concentrated in vacuo to give a crystalline isocyanate, MP 105°-106°C. 

A cooled 10% solution of 1 mol of phosgene in toluene was added with stirring to a cooled solution of 1 mol of 2-methyl-2-propyl-1,3-propanediol and 2 mols of dimethylaniline also dissolved in toluene, at such a rate that the temperature of the mixture was maintained at about 25°C. The mixture was allowed to remain at this temperature for several hours, then... 

However, the reaction with R8eCl (R=4-C1C6H4) gives a mixture of (R8e)28 (n=l-7) and R28e2 [125]. Heating of this mixture results in the formation of a more complicated mixture, (R8e)28 ( =0-10), instead of the convergence to a thermodynamically stable compound. When a toluene solution of phosgene is added to a solution of (TiCp 2)2(p-S2)2 in C82, the acyclic trisulfido complex (TiCp 2Cl)2(p-83) is obtained in 18% yield [130]. 

Methoxypolyethylene glycol of molecular weight 5000 (Union Carbide, 60 g, 12 mmol), dried by azeotropic removal of toluene, was dissolved in toluene/dichloromethane (3 1, 200 mL) and treated with a toluene solution of phosgene (30 mL, 57 mmol) overnight. The solution was evaporated to dryness and the remainder of phosgene was removed under vacuum. The residue was redissolved in toluene/dichloromethane (2 1, 150 mL) and treated with solid N-hydroxysuccinimide (2.1 g, 18 mmol) followed by triethylamine (1.7 mL, 12 mmol). After 3 h the solution was filtered and evaporated to dryness. The residue was dissolved in warm (50 °C) ethyl acetate (600 mL), filtered from a trace of insolubles and cooled to facilitate precipitation of the polymer. The product was collected by... 

Phosgene from a commercial cylinder was used (Matheson Company or Ohio Chemical Company). For the preparation of a solution of phosgene in toluene see Organic Syntheses ... 

The ester is made by adding benzyl alcohol slowly to a preformed solution of phosgene in toluene at 12-16°C, toluene solvent finally being distilled off under vacuum. When discoloured phosgene was used (probably containing iron salts from corrosion of the cylinder), a violent explosion occurred during the distillation phase, presumably involving iron-catalysed decomposition of the chloroformate ester. 

To this mixture, acetonitrile (1.2 mL) and 20% solution of phosgene in toluene (485 pL) were thereto added, and was shaken at room temperature for 1 h. 

Phosgene is highly toxic gas (caution ). Phosgene is a suitable reagent for this method since it can simultaneously activate several functional groups such as amines, carboxylic acids, hydroxyl, etc. Twenty percent of COCl in toluene, almost saturated solution, is commercial available from Aldrich ( 681776). 

A reactor charged with the step 4 product, 75 ml of CH2CI2, and 10.8 ml of pyridine was treated with dropwise addition of 22.5 ml of 1.94 M solution of phosgene in toluene (43.6 mmol) at ambient temperature. The mixture stirred for 3.5 hours and was then diluted with 500 ml of CH2C12 and transferred into a separatory funnel. The mixture was extracted with 0.2 M hydrochloric acid, the organic phase dried over MgS04, concentrated to 150 ml, and precipitated by pouring into 750 ml of hexane and the product isolated. 

The ester is made by adding benzyl alcohol slowly to a preformed solution of phosgene in toluene at 12—16°C, toluene solvent finally being distilled off under... 

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