Online Encyclopedia


Online Encyclopedia
Originally appearing in Volume V04, Page 268 of the 1911 Encyclopedia Britannica.
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C2I15 as a colourless spontaneously inflammable gas of unbearable smell. Boron triethyl B(C2H5)3 is obtained in the same manner, by using zinc ethyl. It is a colourless spontaneously inflammable liquid of boiling point 95° C. By the action of one molecule of ethyl borate on two molecules of zinc ethyl, the compound B(C2H3)2.002I-I5 diethylboron ethoxide is obtained as a colourless liquid boiling at 'of C. By the action of water it is converted into B(C2H5)2.OH, and this latter compound on exposure to air takes up oxygen slowly, forming the compound B•C2H5.002H5.OH, which, with water, gives B(C2Hz)•(OH)2. From the condensation of two molecules of ethyl borate with one molecule of zinc ethyl the compound B2•C2H5. (OC2H5)5 is obtained as a colour-less liquid of boiling point 112° C. Boron triethyl and boron trimethyl both combine with ammonia. The atomic weight of boron has been determined by estimating the water content of pure borax (J. Berzelius), also by conversion of anhydrous borax into sodium chloride (W. Ramsay and E. Aston) and from analysis of the bromide and chloride(Sainte-Claire Deville) ; the values obtained ranging from 10.73 to 11.04. Boron can be estimated by precipitation as potassium fluoborate, which is insoluble in a mixture of potassium acetate and alcohol. For this purpose only boric acid or its potassium salt must be present; and to ensure this, the borate can be distilled with sulphuric acid and methyl alcohol and the volatile ester absorbed in potash.
End of Article: C2I15

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