Phenyl cyanate

Benzhy dr azide.1—24 g. (0-15 mole) of ethyl benzoate (p. 141) are heated for six hours under a small reflux condenser on the water bath with 9 g. of hydrazine hydrate.2 The solid crystalline cake which is formed on cooling is, after some time, filtered as dry as possible at the pump and washed with a little ice-cold methyl alcohol. If the yield is too small the filtrate is concentrated and heated again. 

The crude product (16-18 g.) is sufficiently pure for further treatment. A sample can be recrystallised from hot water or from a little alcohol. Melting point 112°. 

Benzoylazide.3—14 g. (0-1 mole) of the dry hydrazide are made into a clear solution with 200 c.c. of approximately N-hydrochloric acid in a filter jar (capacity 0-5 1.). The solution is cooled in ice and stirred, while 8 g. of sodium nitrite in 50 c.c. of water are added. An immediate reaction takes place and the azide separates in crystalline form. When a filtered sample of the solution is no longer made turbid by the addition of a drop of nitrite solution, the precipitate is filtered dry at the pump, washed well with water, and dried, first on porous plate and then in a vacuum desiccator over concentrated sulphuric acid and potassium hydroxide. Yield 14 g. 

Phenyl Cyanate.4—The azide used for the preparation of the cyanic ester must be absolutely dry. Test for constant weight on a good hand balance. 

Since benzoylazide explodes when rapidly heated or when in contact with concentrated sulphuric acid, it must be handled carefully. Goggles must be worn until the distillation of the phenyl cyanate has been completed. 

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Vinylic copper reagents react with CICN to give vinyl cyanides, though BrCN and ICN give the vinylic halide instead." Vinylic cyanides have also been prepared by the reaction between vinylic lithium compounds and phenyl cyanate PhOCN." Alkyl cyanides (RCN) have been prepared, in varying yields, by treatment of sodium trialkylcyanoborates with NaCN and lead tetraacetate." Vinyl bromides reacted with KCN, in the presence of a nickel complex and zinc metal to give the vinyl nitrile. Vinyl triflates react with LiCN, in the presence of a palladium catalyst, to give the vinyl nitrile." ... 

Both these changes occur together in the decomposition of phenyl cyanate (for preparation see p. 153), C02 and diphenylurea being formed ... 

They react, however, much more slowly. This follows already from the method of preparation of phenyl isothiocyanate (phenyl cyanate is at once decomposed by water). 

Martin et al. briefly reported on the reaction of 4-methyl-5-phenylimino-l,2,3,4-thiatriazoline with phenyl cyanate to give (91) (R = PhO) <85J0C1295>. However, the reaction was carried out in acetone and is now interpreted to proceed via (92) (Scheme 16) <9UHC333>. 

Preparation of tetraalkyl orthocarbonates by the reaction of phenyl cyanate with alcohols in the presence of acids [186]. 

Reaction between 5-alkoxythiatriazole and triphenylphosphine, which is a weaker nucleophile, proceeds more sluggishly.18 At 25° triphenylphosphine reacted exothermically with 5-(4-chlorophenyl)thiatriazole in ether the products were those of total fragmentation, i.e., 4-chloro-phenyl cyanate and triphenylphosphine sulfide, in addition to nitrogen. Since thiatriazaphosphorines normally are stable at room temperature... 

Yields are variable, but in favourable cases can be very high for example, phenyl cyanate and t-butylmagnesium chloride gave pivalonitrile (92%) and phenol (87%). 

Phenyl-2-adamantanamine, 60, 105 2-PHENYL-2-ADAMANTANAM1NE HYDROCHLORIDE, 60, 104 2-Phenyl-2-adamantanol, 60, 105 Phenylchlorodiazirine, 60, 55 PHENYL CYANATE, 61, 35 l-Phenyl-2,2-diethoxycyclopropane, 60, 8 Phenylmercuric acetate, 61, 82... 

CYANIC ACID ESTERS FROM PHENOLS PHENYL CYANATE... 

An indirect method involves the reaction of an aromatic ring with tert-butyl-lithium, particularly when there is a directing group (see 13-17), followed by reaction with PhOCN (phenyl cyanate) to give the aryl nitrile. another indirect method involve the palladium catalyzed reaction of aryl bromides with the cyanohydrin of acetone [Me2C(OH)CN] to give ArCN. ... 

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