Trof. Pope, Compensated Bases and Dihydropapaverine. 545 



The Resolution of Externally Compensated Bases into their 

 Optically active components. By Professor Pope and Mr J. Read. 



[i?earf23May 1910.] 



The authors show that when the resolution of an externally 

 compensated acid (or base) is attempted by crystallisation with an 

 optically active base (or acid), one of three different kinds of 

 behaviour is to be observed. (1) The two salts, d-B, d-A, and 

 d-B, I- A, which are capable of formation, are readily separable by 

 crystallisation and show no tendency to form solid solutions one 

 in the other; in this case an easy separation is effected by the 

 method of Pope and Peachey. (2) The two salts, d-B, d-A and 

 d-B, I- A, combine to form a partially racemic compound; in this 

 case no resolution occurs. (3) The two salts, d-B, d-A, and d-B, 

 I- A, form solid solutions one in the other, and separation by frac- 

 tional crystallisation is slow and very incomplete. 



Behaviour of the type (3) has not been previously distinguished 

 and a number of cases of its occurrence were described. 



The Resolution of Dihydropapaverine. By Professor Pope 

 and Mr C. S. Gibson. 



[Read 23 May 1910.] 



The resolution of externally compensated dihydropapaverine 

 into its optically active components was effected by Pope and 

 Peachey by crystallisation with cZ-a-brompcamphor-Tr-sulphonic 

 acid ; the less soluble salt, l-B, d-A, is crystalline and may be 

 separated from the salt, d-B, d-A, which is resinous, by fractional 

 crystallisation. It is now shown that the resolution is more 

 easily effected by dissolving the externally compensated base in 

 an equivalent proportion of c^/3-camphorsulphonic acid and adding 

 to the aqueous solution one-half an equivalent of ammonium 

 cZa-bromocaraphor-TT-sulphonate; after separating the crystalline 

 salt of the laevo-component of the alkaloid which is deposited 

 the purification of the residual dextro-base is effected by crystalli- 

 sation of its ^«'bromocamphor-7r-sulphonate. 



