Naphthyl isocyanates

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 ... 

Amino acids react in alkaline solution with a-naphthyl isocyanate to yield the sodium salts of the corresponding a-naphthylureido acids, which remain in solution upon addition of a mineral acid, the ureido acid is precipitated. 

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. 

According to the submitters l-cyano-S-a-naphthylurea is obtained similarly from a-naphthyl isocyanate in 85-90% yields. Crystallization from acetone-petroleum ether (12 and 6 ml., respectively, per gram of crude product recovery approximately 60% per crystallization) yields lustrous prisms, m.p. 148-149 with decomposition. 

Preparation of the naph yl-urethane. This compound is prepared in a similar method to that just described, using a-naphthyl-isocyanate. The naphthyl-urethane melts at 53°. 

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

The triethylamine was purified by treatment with naphthyl isocyanate and distilled the distillate was stored over sodium wire. 

AEOs have been analysed by HPLC and UV or fluorescence detection after suitable derivatisation. The derivatising agents proposed so far are phenyl isocyanate [80,81], 1-anthroylnitrile [82], 3,5-dinitro-benzoyl chloride [83], naphthyl isocyanate [84] and naphthoyl chloride [84], However, the lack of fluorescence activity and the need for synthesis through a multistep reaction for some derivatising agents limits their application in a real-world analysis. In fact, only a few of them were applied in the determination of AEOs in environmental samples. Zanette et al. [84] developed derivatisation and separation... 

The cyclic carbamate (oxazolidin-2-one) 313 is formed by the reaction of phenyl isocyanate (312) with vinyloxirane[192]. 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 1) by the reaction of 2-methoxy-l-naphthyl isocyanate (314) with a vinyloxir-... 

Reaction of a-naphthyl isocyanate and hydrazides to yield l-acyl-4-arylsemicarbazides [90]. 

The reaction of a-naphthyl isocyanate with alcohols has been reported to be a convenient analytical method for the preparation of solid derivatives [16-18]. In addition, the by-product dinaphthylurea is very insoluble in hot ligroin (b.p. 100°-120°C). The urethanes are readily soluble in hot ligroin, and on cooling the solution they recrystallize to sharp-melting solids. It is recommended that two recrystallizations be performed to obtain substances for analysis. Primary alcohols react well without the need for heating the reaction mixture. Secondary alcohols require additional heat, and the yields of urethane oft are smaller than when primary alcohols are used. Tertiary alcohols other than /-butyl [17] or /-amyl [17] were not able to react under the conditions used. Table V lists some representative alcohols and their a-naphthylurethane derivatives. 

To a small flask or test tube are added 2-3 gm of the alcohol and a slight stoichiometric excess of the a-naphthyl isocyanate. If the reactants do not react immediately to give a solid product, heat is applied. The contents of the flask are extracted with boiling ligroin (b.p. 100°-120°C) which dissolves the urethane but leaves the insoluble dinaphthylurea. 

In the case of cinnamyl alcohol, menthol, borneol, isoborneol, cholesterol, and benzoin, the alcohol is dissolved in approximately 10 ml of ligroin before it reacts with a-naphthyl isocyanate. 

Phenols but not polyhydroxybenzenes also react with a-naphthyl isocyanate to give a-naphthylurethanes. In some cases in which solid derivatives were difficult to obtain, the addition of 1 or 2 drops of triethylamine solution in ether... 

Naphthylazoamines, 287 a-Naphthyl isocyanate, 141 a-Naphthyl ureas, 141 a-Naphthylurethanes, 230-232 a-Nitrile azo compounds, 324 Nitrite salts, 427 Nitrites... 

Using 9.2 mmoles each of o-cresol and a-naphthyl isocyanate in 3.00 ml of purified ligroin, the effect of catalysts was tested. The sealed tubes were heated in a 65°C bath and after a definite time the solid urethane derivative was isolated, washed, dried, and weighed. The results (see Fig. 1) show that tri-ethylamine is the most effective amine, boron trifluoride etherate being the most effective acid tested at that time [7]. 

Fig. 1. Effect of catalysts on the rate of reaction of o-cresol and a-naphthyl isocyanate [7]. Reprinted from D. S. Tarbell, R. D. Mallatt, and J. W. Wilson, J. Amer. Chem. Soc. 64,2229 (1942). (Copyright 1942 by the American Chemical Society. Reprinted by permission of the copyright owner.)...

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