DERIVATIVES OF BIPHENYL 231compounds or N-nitrosoacetyl derivatives have been prepared and someof the compounds which have been used for coupling. It is apparent that,by the proper .combination of reagents, derivatives of biphenyl, the ter-phenyls, phenylnaphthalenes, phenylthiophenes, and phenylpyridinescan be prepared.With the diazohydroxides the yields usually lie between 15 and 35%,although in some instances they are much lower; with the nitrosoacetylderivatives the yields are generally higher, lying between 40 and 70%.In some reactions in which the diazohydroxide fails to give the desiredproduct, the nitrosoacetyl derivative may give it. Moreover, the modi-fications, such as the use of sodium acetate or the stabilized diazoniumsalts,occasionally serve to improve the yield in the diazo reaction. Evenwhen the yields are low, these methods are often the only ones availablefor preparing substances of definite structure for purposes of identifica-tion.
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