— 168 — 



sponding urethanes in a better yield than diphenyl urea chloride 

 itself, it must no doubt be considered as an intermediate product in 

 the above reaction. 



The diphenyl urethanes can very readily be saponified. The 

 formation of urethanes is suitable for the purification and identification 

 of phenols; the yield fluctuates between 70 and 90 /o of tne quantity 

 calculated theoretically. 



Of the phenol-diphenyl urethanes produced there may be mentioned 

 eugenol diphenyl urethane (C 6 H 5 ) 9 N»CO«O«C 10 H 11 O, m. p. 107 

 to 108 . 



With regard to the determination of hydroxyl groups according 

 to Zerewitinoff, see under Analytical Notes, p. 117. 



In the numerous treatises by Pond, Hell, and Hoering, which 

 we have discussed from time to time, it has been shown that in the 

 dibromides of the aromatic propenyl ethers, the bromine atom which 

 is situated nearest to the benzene-nucleus is readily exchanged for OH 

 and other radicals. Tiffeneau and Daufresne found 1 ) that the dibrom- 

 ides of the isomeric allylphenyl ethers R«CH 2 »CH Br «CH 2 Br behave 

 in an analogous manner; when heated with alcoholic potassium acetate, 

 they exchange the bromine atom next to the benzene nucleus for 

 OCOCH 3 , and yield acetobromohydrins. When these are boiled 

 with alcoholic potash, they split off acetyl and bromine and are con- 

 verted in substituted cyclopropanols (I), whilst the acetobromohydrins 

 of the isomeric propenyl derivatives in such case of course yield 

 ethylene oxides (II). From these oxides, and the isomeric oxides (III)., 



R.CH— CHOH R.CH.CH.CH3 R.CH 2 .CH.CH 2 



i. \/ 11. \y in. \/ 



CH 2 O O 



the cyclopropanols, like the corresponding acetates, differ by their 

 specific gravity, which is about 0,06 units higher, but chiefly by the 

 fact that they can be converted into substituted hydratropic aldehydes 



R.CH(CH 3 )CHO 

 under the same conditions under which the oxides are converted 

 into arylacetones R«CH 2 «CO«CH 3 and hydrocinnamic aldehydes 

 R • CH 2 • CH 2 • CHO respectively. From the allyl dibromides directly, 

 the hydratropic aldehydes (and also cyclopropanols) are formed by 

 boiling with aqueous potash solution. The following derivatives of 

 estragol and safrol were produced: 



1. Estragol. Dibromide (by brominating in a cold solution of 

 carbon disulphide): d i7 o 1,639, b. p. 188 to 192 (18 mm. pressure); 



*) Compt. rend. 144 (1907), 924. 



