1876.] Dr. E. Erankland on Organo-boron Compounds. 165 



XVIII. ''^On Organo-boron Compounds."^ By E. Erankland, 

 D.C.L., F.E.S. Received June 14, 1876. 



In a former communication to the Eoyal Society* I described the action 

 of zincethyl and zincmethyl upon boric ethylate, and showed that these 

 organo-metallic bodies displace the ethoxyl (Eto=:C2HgO) of the ethylate 

 by the organic radical which they contain. Thus the action of zinc- 

 methyl upon boric ethylate is expressed by the following equation : — 

 BEtOg + SZnMe, = BMcg + SZnMeEto. 



Boric ethylate. Zincmethyl. Boric methide. Zincic methoethylate. 



It was also shown that spontaneously inflammable boric ethide (BEtg), 

 when cautiously exposed to a slow current, first of air and then of 

 oxygen, combines with two atoms of oxygen forming boric ethodiethylate 

 (BEtEto.J — a liquid boiling with partial decomposition between 95° and 

 125° C, but capable of being distilled without change in vacuo. By 

 "contact with water, this compound was instantly transformed into boric 

 ethodihydrate, thus : — 



BEtEfco, + OH, = BEtHo, + 2EtHo. 



Boric ethodiethylate. Water. Boric ethodihydrate. Alcohol. 



I have recently resumed the investigation of these compounds, and 

 have obtained results of which the following is a preliminary description. 



Boric EtJiide. 



Instead of using boric ethylate and zincethyl for the preparation of 

 this compound, it may be obtained by passing a current of the vapour of 

 boric chloride through zincethyl. The reaction appears to take place 

 according to the following equation : — 



BCI3 + 3ZnEt, = BEtg + SZnEtCl. 



Boric chloride. Zincethyl. Boric ethide. Zincic ethochloride. 



Diboric EtJiopentethylate. 

 When equal molecules of boric ethylate and zincethyl are digested at 

 about 100° C. for four or five hours, and then submitted to distillation, 

 there is obtained a liquid distillate, which yields, on rectification, a con- 

 siderable fraction boiling at 110° to 113° C, whilst zincic ethoethylate is 

 left in the retort. On analysis this liquid was found to consist of equal 

 molecules of boric ethylate and boric ethodiethylate. The following 

 equation explains the reaction : — 



2BEt03 + ZnEt, = BEtEto,, BEtOg + ZnEtEto. 



Boric ethylate. Zincethyl. Diboric ethopentethylate. Zincic ethoethylate. 



The new compound is a colourless mobile liquid boiling at about 

 112° C, and condensing again unchanged. It possesses a slight ethereal 

 odour and a sweetish taste. The specific gravity of its vapour, taken at 

 114° and 120° C, is 69 (H=l), which agrees exactly with the calculated 

 ^ Phil. Trans, vol. clii. p. 167. 



