A-Naphthyl isocyanate

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. 

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.)...

Anilides and a-Naphthalides. The Grignard reagents prepared from alkyl halides react with phenyl isocyanate (CsH5N=C=0) or with a-naphthyl isocyanate (C10H7 N=C=O) to yield addition products that are converted by hydrolysis into anilides and a-naphthalides respectively ... 

P-Naphthyl benzoate, 784 a-Naphthylcarbamates, 364 a-Naphthyl isocyanate, 264, 291 a-Naphthylhydantoic acids, 437 P-Naphthyl methyl ether, 665, 670, 767... 

The 1,3-diazetidine derivatives are most commonly synthesized by the dimerization of heterocumulenes. At elevated temperature they undergo dissociation and are in equilibrium with their monomers. For example, 1,3-diazetidine 108, formed by the reaction of a-naphthyl isocyanate 106 with dicyclohexylcarbodiimide 107, upon thermal dissociation furnished products of its [2+2] cycloreversion reaction, that is, cyclohexyl isocyanate 110 and a-naphthylcyclohexylcarbodiimide 109 (Scheme 10) <1962AGE621>. 

Triethylamine purified by drying over sodium hydroxide pellets and distilling from a-naphthyl isocyanate was found to give no better results than amine which had been distilled through a half-meter Vigreux column and collected over the range 89.5-90°. 

Anilides, toluides, and a-naphthalides ate prepared from phenyl, p-tolyl, and a.-naphthyl isocyanates, respectively, by reaction with a Grignard reagent. The reaction is valuable for the identification of halogen compounds of the type that form organometallic derivatives. The reaction occurs in ether solution at room temperature. In general, the yields of N-arylamides are excellent. This method has been used in the preparation of N-(a.-furyl)-propionamide (89%). ... 

Form Supplied in racemic, (R), and (S) forms all as colorless, neat liquids. Solid derivatives phenyl isocyanate, mp 60 °C a-naphthyl isocyanate, mp 102 °C. 

The catalytic activity of hydrogen chloride was found by Tarbell and Kincaid 34g). Continuing this work, Tarbell et al. 36) showed that certain acids and bases affect the yields of urethanes obtained from a-naphthyl isocyanate and phenols. Thus, catalytic effects were observed with sodium carbonate and acetate, pyridine, triethylamine, acetic acid, trichloroacetic acid, zinc chloride, hydrogen chloride, and boron fluoride etherate. The latter catalyst and triethylamine were found to be the most effective acidic and basic catalysts, respectively. 

---