For a number of years the authors and their collaborators B. M. Tumermari, T. P. Vishnyakova, M. V. Kurashev, F. F. Machus have been studying the catalytic transformations of hydrocarbons in the presence of boron fluoride a.nd catalysts based on it.

These investigations were published in a number of works and monographs by the authors of this report in the course of the past few years (1-4).

In the present report some of the results of these investigations are discussed.

I. Boron Fluoride and its Compounds

Boron fluoride is a catalyst which is widely used in scientific research work and in industry.

The field of application of boron fluoride is constantly expanding, and therefore interest in this catalyst is becoming greater and greater.

Boron fluoride is used as a catalyst in its pure form, as well as in its numerous compounds with organic and inorganic substances. A number of articles and books have been published on this question in recent years.

Boron fluoride melts at -127.10; its boiling point is -100.40 at 760 mm Hg. The critical temperature of boron fluoride is -12.240, its critical pressure 49.2 atm.

Mass spectrographic investigation has proven the presence of the Bio and Bii isotopes in gaseous bofon fluoride. The heat of formation of boron fluoride from its elements is 273.5 large calories per mole. (*) Title Only Paper. (* *) Academy of Sciences, Moscova, LJSSR.

Boron fluoride is very soluble and forms molecular compounds in substances containing oxygen atoms. Thus, at 00 and 762 mm, 1.19 g of water absorbs 3.832 g of BF3, which is equivalent to the absorption of 1057 ml of gaseous boron fluoride in 1 ml of water. The reaction of solution is accompanied by the evolution of 24.5 large calories per mole. One volume oÍ' concentrated HzSOa of specific weight 1.85 absorbs 50 volumes of BF3; other oxygencontaining acids likewise dissolve boron fluoride. (4,5) Hydrocarbons arid their chlorine derivatives dissolve an insignificant quantity of boron fluoride; they are usually considered inert liquids with regard to BF3. The solubility of BF3 in n-pentane at 490 and 930 and at pressures between 3.8 and 14.8 atm. is from 1 to 12 ml of BFB per 1 g of n-pentanr. Boron fluoride forms numerous molecular compounds with compounds containing oxygen, which is due to the strong tendency of the boron atom to accept one electron and pass into a new valent state (tetravalent negative), and of the oxygen atom to give up one electron, changing into a trivalent positively charged atom.

The change in valency and in the number of bonds leads to a change in the configuration of the BF3 molecule from plane to tetrahedral, the three fluorine atoms and the oxygen atom being located in the corners of the tetrahedron and the boron atom in the

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