2- phenyl isocyanate

Powdered a,oc -dibromo-m-xylene (88 g. or 0.33 mole) (p. 105) is added to a boiling solution of 50 g. (0.77 mole) of potassium cyanide in 110 ml. of water and 350 ml. of ethanol. The solid is added as rapidly as the vigorous exothermic nature of the reaction will allow, and the reaction mixture is stirred during this operation. The resulting mixture is filtered hot, and the filtrate is diluted with 1 1. of water. The mixture is extracted with ether, and the ethereal solution is dried and distilled to give 47 g. (91%) of the dinitrile, b.p. 230-231°/20 mm., m.p. 27°. 

A solution of 93 g. (1.0 mole) of aniline in 1 1. of toluene is heated to around 70°, and dry hydrogen chloride gas is introduced until the mixture is saturated. (Hood.) The mixture is then heated to boiling, 

A solution of 55 g. (0.33 mole) of 4-aminobiphenyl in 500 ml. of toluene treated as above, and the toluene removed by distillation, gives p-isocyanobiphenyl. The product is recrystallized from petroleum ether (b.p. 40-60°) to give 58 g. (91%) of product. (Cf. preparation of o-isocyanobiphenyl, p. 186.) 

A mixture of 200 g. (1.0 mole) of phenothiazine, 306 g. (1.50 mole) of iodobenzene, 120 g. of anhydrous sodium carbonate, and 10 g. of copper powder is stirred and heated to reflux for 12 hours. The reaction mixture is steam-distilled until all steam-volatile material has been removed. The solid residue remaining in the steam-distillation vessel is separated, dried, and distilled to give 176 g. (64%) of 10-phenylphenothiazine boiling at 220-223°/l mm. and melting at 92-93°. Recrystallization from glacial acetic acid gives white prisms melting at 94.5°. 

Phenylmagnesium bromide is prepared in customary manner [Org. Syntheses Coll. Vol. 1, 550 (1941)] from 24 g. (1.0 gram atom) of magnesium, 185 g. (1.2 moles) of bromobenzene, and 400 ml. of dry ether. The solution of the Grignard reagent is cooled in an ice-salt bath and stirred while a solution of 56 g. (1.0 mole) of acrolein [Org. Syntheses Coll. Vol. 1, 15 (1941)] in 250 ml. of ether is added drop-wise. Stirring is continued for a few hours, after which a mixture of ice and dilute sulfuric acid is added cautiously until an excess is present. The ether layer is separated, washed with water and dilute sodium bicarbonate solution, dried over anhydrous sodium sulfate, and distilled. There is obtained 82 g. (61%) of product boiling at 106-107715 mm. 

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D) Phenylurea Derivatives. This reaction usually proceeds readily when cold solutions of the dried amine and of phenyl isocyanate, each in petroleum (b.p. 100-120 ), are mixed if no reaction is obvious, heat under reflux for 30 minutes. Care in using the isocyanate, p. 336.)... 

Phenyl- and a-naphthyl-urethanes (Phenyl- and a-naphthyl-carbamates). Both phenyl isocyanate and a-naphthyl isocyanate react with alcohols to yield phenyl-urethanes and a-naphthyl-urethanes respectively ... 

Anilides and a-Naphthalides. The Grignard reagents prepared from alkyl halides react with phenyl isocyanate (CgHjN=C=0) or with a-uaphthy l isocyanate (C,oH, N=C=0) to yield addition products that are converted by hydrolysis into anihdes and a-naphthalides respectively RX + Mg —> RMgX... 

Phenyl isocyanate is a colourless liquid, b.p. 164° or 55°/13 mm. its vapour is lacluymatory. The liquid reacts readily with water, yielding diphenyl urea, m.p. 241°, and hence must be protected from atmospheric moisture ... 

The phenylhydantoic acid is prepared similarly, using phenyl isocyanate. The latter is more sensitive to water than a-naphthyl isocyanate and therefore does not keep so well. 

Alcohols (but not ethers) also react with phenyl isocyanate or with the corre-sponding crystalline a-naphttiyl isocyanate to give carbamates or urethanes (see Section 111,27, ), but these substances are hardly suitable as class reagents. 

The cyclic carbamate (oxazoIidin-2-one) 313 is formed by the reaction of phenyl isocyanate (312) with vinyloxirane[I92]. Nitrogen serves as a nucleophile and attacks the carbon vicinal to the oxygen exclusively. The thermodynamically less stable Z-isomer 315 was obtained as a major product (10 I) by the reaction of 2-methoxy-l-naphthyI isocyanate (314) with a vinyloxir-... 

Reductive carbonylation of nitro compounds is catalyzed by various Pd catalysts. Phenyl isocyanate (93) is produced by the PdCl2-catalyzed reductive carbonylation (deoxygenation) of nitrobenzene with CO, probably via nitrene formation. Extensive studies have been carried out to develop the phosgene-free commercial process for phenyl isocyanate production from nitroben-zene[76]. Effects of various additives such as phenanthroline have been stu-died[77-79]. The co-catalysts of montmorillonite-bipyridylpalladium acetate and Ru3(CO) 2 are used for the reductive carbonylation oLnitroarenes[80,81]. Extensive studies on the reaction in alcohol to form the A -phenylurethane 94 have also been carried out[82-87]. Reaction of nitrobenzene with CO in the presence of aniline affords diphenylurea (95)[88]. 

Double. silylation of the a-diketone 120 with (Me3Si)2 is catalyzed by PdCl2(Me3P)2 to give the l,2-bis(siloxy)ethylene 121 in a good yield[ll7], Hydro.silylation of phenyl isocyanate (122) catalyzed by PdCN affords the /V-... 

The nucleophilic reacbvity of the C-5 oxygen is well documented however, no quantitative data are available. A-2-Thiazoline-5-ones (212) react at oxygen with acetyl chloride or acetic anhydride (447. 452). benzoyl chloride (447). methyl or phenyl isocyanate (467). carbamoyl chloride (453, 467). or phosphorus derivatives (468, 428) in the presence of bases to give 213, 214, 215. or 216 (Scheme 109). Strong bases such as... 

Methylenebis(4-phenyl isocyanate). This compound is also known as methyl diisocyanate [101-68-8] (MDI) and is produced by the condensation of aniline and formaldehyde with subsequent phosgenation. Its principal end use is rigid urethane foams other end uses include elastic fibers and elastomers. Total formaldehyde use is 5% of production (115). 

Amides result from the reaction of aromatic hydrocarbons with isocyanates, such as phenyl isocyanate [103-71-9], ia the presence of aluminum chloride. Phenyl isothiocyanate [103-72-0] similarly gives thioanilides (136). 

Sodium methanenitronate reacts with phenyl isocyanate in benzene to give the readily separable sodium salts of nitroacetaniUde and nitromalondiarkhde. Except as the salt, nitromethane is unreactive with phenyl isocyanate at temperatures up to 100°C the higher homologues do not give condensation products that can be isolated. 

The hydroxyl number can be deterrnined in a number of ways such as acetylation, phthalation, reaction with phenyl isocyanate, and ir and nmr methods. An imidazole-catalyzed phthalation has been used to measure the hydroxyl number for a number of commercial polyether polyols and compared (favorably) to ASTM D2849 (uncatalyzed phthalation) (99). The uncatalyzed method requires two hours at 98°C compared to 15 minutes at the same temperature. 

Liquid Ghromatography/Mass Spectrometry. Increased use of Hquid chromatography/mass spectrometry (Ic/ms) for stmctural identification and trace analysis has become apparent. Thermospray Ic/ms has been used to identify by-products in phenyl isocyanate precolumn derivatization reactions (74). Five compounds resulting from the reaction of phenyUsocyanate and the reaction medium were identified two from a reaction between phenyl isocyanate and methanol, two from the reaction between phenyl isocyanate and water, and one from the polymerisation of phenyl isocyanate. There were also two reports of derivatisation to enhance either the response or stmctural information from thermospray Ic/ms for linoleic acid hpoxygenase metabohtes (75) and for cortisol (76). 

The acetyl content of cellulose acetate may be calculated by difference from the hydroxyl content, which is usually determined by carbanilation of the ester hydroxy groups in pyridine solvent with phenyl isocyanate [103-71-9J, followed by measurement of uv absorption of the combined carbanilate. Methods for determining cellulose ester hydroxyl content by near-infrared spectroscopy (111) and acid content by nmr spectroscopy (112) and pyrolysis gas chromatography (113) have been reported. 

Cyanuric acid readily dissolves in aqueous formaldehyde forming tris(hydroxymethyl)isocyanurate [10471-40-6] (THMIC) which can be isolated by evaporation (11). THMIC in turn reacts with acetic anhydride to yield tris(acetoxymethyl)isocyanurate [54635-07-3], either thionyl chloride or phosphoms pentachloride to give tris(chloromethyl)isocyanurate [63579-00-0], and phenyl isocyanate in pyridine to yield tris(A/-phenylcarbamoxymethyl) isocyanurate [21253-39-4] in 87% yield (65). Reaction of CA with paraformaldehyde and 2,6-dicyclohexylphenol yields... 

Ethoxy-6-methylpyrimidine 1-oxide (499) reacts with phenyl isocyanate to eliminate carbon dioxide and give a mixture of 4-ethoxy-6-methyl-N-phenylpyrimidin-2-amine (SOO) and (the derived) 7V-(4-ethoxy-6-methylpyrimidin-2-yl)-7V,7V -diphenylurea (SOI) phenyl isothiocyanate reacts quite differently (79CPB2642). 

Substituted imidazoles can be acylated at the 2-position by acid chlorides in the presence of triethylamine. This reaction proceeds by proton loss on the (V-acylated intermediate (241). An analogous reaction with phenyl isocyanate gives (242), probably via a similar mechanism. Benzimidazoles react similarly, but pyrazoles do not (80AHC(27)24l) cf. Section 4.02.1.4.6). 

Enamines and enolate anions react with benzofuroxan to give quinoxaline di-A -oxides (Scheme 38) (69AHC(10)1). Sydnones (274) with phenyl isocyanate give 1,2,4-triazoles (275) (76AHC(19)l), and from (276) the intermediate adduct (277) can be isolated (73JA8452). This is one of the few instances in which such primary cycloadducts have been isolated in the oxazole series of mesoionic compounds. 

Aziridinones are also known to undergo cycloaddition reactions. Thus, treatment of (321) with phenyl isocyanate gave adducts (335) and (336) (76CL47). 

Rearrangement involving cleavage of the C—O bond is also observed with the phenyl isocyanate adduct (59). In place of an O-acylated nitrone its product (60) of acyl migration is isolated (67JPR(36)86). 

Phenyl isocyanate reacts with (82) to form (83) by ring enlargement (74JOC948). Reaction of oxaziridines with diphenylketene proceeds less obviously. Isolated products (84) and (85) contain only the R—N group of the starting material (69TL263). 

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