4- Nitrophenyl-isocyanate

About two-thirds of the carbon tetrachloride is distilled. The solution is cooled, and the crystals of />-nitrophenyl isocyanate are filtered as quickly as possible in order to avoid prolonged exposure of the compound to the moisture of the air. By concentration of the mother liquor a further crop is obtained. The product is recrystallized from dry carbon tetrachloride and is obtained in the form of light yellow needles melting at 56-57° (Note 6). The yield after one recrystallization is 152-170 g. (85-95 P r cent of the theoretical amount) (Note 7). 

The crude residue is a mixture of -nitroaniline hydrochloride, />-nitrophenyl carbamyl chloride, /7-nitrophenyl isocyanate, and the />, -dinitrodiphenylurea. The -nitrophenyl carbamyl chloride is converted to -nitrophenyl isocyanate during recrystallization from the hot carbon tetrachloride. 

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. ... 

Alcohols Apply sample solution, then nitrophenyl isocyanate solution (10% in benzene) Dry after reacting and develop [72]... 

Nitroindole 418 Nitrophenyl isocyanate reagent 77 1-Nitropyrene 61 N-Nitrosamines 107... 

The isocyanates used are phenylisocyanate, 4-nitrophenyl-isocyanate, and 4-methoxyphenylisocyanate, all purchased from Aldrich Chemical. 

British Drug Houses Ltd. or Matheson Laboratory reagent-grade phenyl isocyanate was used without further purification. When using other isocyanates, care should be taken to ensure their purity as the yield is greatly dependent upon this, commercially available p-nitrophenyl isocyanate being a case in point. 

The yields from the reactions, carried out at room temperature and a pressure of 2-4 at, increase with increasing electronegativity of the substituent X. The yield with phenyl isocyanate is 13%, with p-chlorophenyl isocyanate 55% and with p-nitrophenyl isocyanate it is 100%. Primary and secondary carba-moylphosphines cannot be isolated even when equi-molar quantities of phosphine and isocyanate are used. Their intermediate formation is probable but apparently they are more reactive towards isocyanates than phosphine itself. Similarly, phosphine does not react with free cyanic acid whereas primary and secondary phosphines react with cyanic acid, as with isocyanates, to form the corresponding carbamoylphosphines Attempts to make phosphine react with phenyl isothiocyanate did not succeed... 

Nausea that accompanies the administration of cancer chemotherapy agents was resistant to drug intervention until the introduction of the serotonin receptor antagonist odansetron (see Chapter 13). The benzimidazolone-based compound itasetron (57-6) has much the same activity as its tricylcic predecessor. Condensation of 2-nitrophenyl-isocyanate (57-1) with the bridged bycyclic diamine (57-2) leads to the addition... 

In the case of aromatic isocyanates, electron-withdrawing groups increase the rate of carbodiimide formation in proportion to their electron-withdrawing power. Electron-releasing groups tend to inhibit the reaction. p-Nitrophenyl isocyanate reacts almost explosively to yield the carbodiimide when catalyzed [5]. o-Chlorophenyl isocyanate reacts seven times as fast as the o-methyl analog [33]. 

The Step 4 product (0.394 mmol) dissolved in 5 ml CH2C12 was treated with 3-nitrophenyl isocyanate (0.591 mmol) at ambient temperature, then stirred overnight. The mixture was filtered, then washed with CH2C12, and the product isolated in 79% yield. 

An abnormal aza-Wittig reaction is observed in the reaction of a polymer bound iminophosphoranes with electron poor isocyanates, such as p-nitrophenyl isocyanate. With aliphatic isocyanates the regular aza-Wittig reaction occurs. ... 

C7H3FN203 4-ftuoro-2-nitrophenyl isocyanate 90774-51- 25.00 1.5571 2 9708 C7H4CIN03 p-nitrobenzoyl chloride 122-04-3 25.00 1.4903 2... 

C7H3FN203 4-fluoro-3-nitrophenyl isocyanate 65303-82-4 25.00 1.4530 1 9709 C7H4CIN03 4-chloro-3-nitrobenzaldehyde 16588-34-4 25.00 1.4903 2... 

C8H6CIN 2-chloro-6-methylbenzonitrile 6575-09-3 24.33 1.2048 2 12894 C8H6N203 4-methyl-3-nitrophenyl isocyanate 13471-69-7 25.00 1.3919 2... 

C8H6CINO 5-chloro-2-methyibenzoxazole 19219-99-9 25.00 1.2191 2 12896 C8H6N203 2-methyl-4-nitrophenyl isocyanate 56309-59-2 25.00 1.3919 2... 

The submitters report a similar yield on a scale three times that illustrated here. This method has been employed for the preparation of the 4-methyl- (100%, m.p. 143° from ethyl acetate), 4-i-butyl- (100%, m.p. 147° from ethyl acetate), and 4-p-nitrophenyl-l-carbethoxysemicarbazide (90%, m.p. 219° from methanol). Because of the impure nature of commercial p-nitrophenyl isocyanate, the produet from that reaction may be contaminated with 2 -nitrophenylurea. It can be used in this impure form for preparing the corresponding urazole, as the contaminant is alkali insoluble. 

With the introduction of nitro groups in phenyl isocyanate, the yield of the amines increases at the expense of the ureas. 2,4-Dinitro- and 2,4,6-tri-nitrophenyl isocyanates gives only amines. The introduction of a methoxy or methyl group in para position decreases the amine yield. The amine yield increases in the following series ... 

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