Cyclic compounds of boron: alkenoxy boroxines

Alkenoxy boroxine derivatives with the general formula, O3B3(OR)3 [where R = -CH2CH=CH2, -CH2CH=CHCH3, -CH2CH2CH=CH2, -CH2CH2CH2CH=CH2, -CH2C(CH3)=CH2, -CH(CH3)CH=CH2, -CH(CH3)CH2CH=CH2, -CH(CH3)CH=CHCH3 and -CH(C2H5)CH=CHCH3] have been synthesized by heating an equimolar mixture of the corresponding alkenyl orthoborate and boric oxide. A trimeric ring structure for these derivatives has been proposed on the basis of molecular weight determinations and IR as well as PMR studies. On heating under reduced pressure these products disproportionate to give the corresponding volatile alkenyl orthoborates