as alcohol does to methane, is called a carbinol. A carbinol is 

 methyl alcohol in which one or more of the hydrogen atoms may 

 have been replaced with an alkyl radical or a benzene ring. Thus : 



OH 



diphenyl carbinol 



It is next theoretically possible to attach amino groups to the ben- 

 zene rings. Thus in the case of di-phenyl carbinol it is possible to 

 obtain di-amino di-phenyl carbinol: 



NH2 



H.N 



Now this latter compound contains the necessary auxochrome 

 groups; but it is not yet a dye. Xo carbinol is a dye, because it 

 lacks a chromophore group. The carbinols are important in dye 

 chemistry, however, because upon dehydration a rearrangement of 

 the bonds in the molecule takes place giving the quinoid benzene 

 ring, which as we have seen is a powerful chromophore. Thus: 



H.N 



NH.^H.N_/~\_C 



,NH+H.O 



Now this latter compound is the anhydride of a true dye base. 

 Upon hydration it should theoretically become: 



H.N 



Such a compound could exist only in watery solution, 

 only by its salts, the true dyes, as: 



It is known 



H.N 



Altho the theoretical compound given above is the true dye base, 

 the carbinols are often known as carbinol bases of the phenyl 

 methane dyes or are sometimes called leuco-bases or color bases. 

 They are not bases in the chemical sense, however, as they do not 



59 



