The present is the first of a series of papers describing new developments in the methods of preparation and in the chemistry of diborane and of the borohydrides. New and practical methods for the preparation of borohydrides (a) from diborane, and (b) without the use of diborane are discussed. As a result of the availability of borohydrides, prepared without the use of diborane, methods, far more satisfactoiy than those hitherto known for the preparation of the latter, have been developed. The investigation has led to the preparation of the hitherto unknown borohydrides of sodium, of potassium and of uranium, and some of their derivatives, as well as of a new type of substance, such as sodium trimethoxyborohydride, NaBH(OCH3)3, formed by the addition of compounds of trivalent boron to alkali metal hydrides. Sodium borohydride, as well as sodium trimethoxyborohydride, are of special interest because of their potential usefulness as reducing agents and sources for the generation of hydrogen; uranium(IV) borohydride and its derivatives are of interest because they are the most volatile compounds of uranium except the hexafluoride. The present paper surveys numerous new observations made and organizes the subject matter in the light of the principle which largely guided the research, namely, the application of the Lewis generalized acid-base concept to the reactions of diborane, of the salt-like hydrides and of the borohydrides. Detailed description of the new preparative methods and data confirming the reaction equations herein presented as well as supporting the composition of new substances are deferred to the remaining papers of the series.vestigations carried out under contracts with the National Defense Research Committee, with the Office of Scientific Research and Development and with the Signal Corps, Ground Signal Agency during the years 1940-1944. They were continued under Navy auspices during [1944][1945][1946]. Most of the results were originally described in the final reports on contracts NDC-rc-56, 9820 and 10,421.

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Ill butadiene plants and in the monomer (butadiene and styrene) recovery units of copolymer plants, the monomers have a tendency to form a hard benzene-insoluble material resembling popcorn.An outstanding characteristic of this popcorn polymer is its ability to grow rapidly when exposed to monomers.A hypothesis is presented here to explain the mechanism of this growth, and various means are suggested for preventing the growth under plant conditions.D is also shown that under proper conditions a water solution of sodium nitrite is an outstanding inhibitor for the thermal polymerization of styrene and is far superior to the best organic antioxidants. BY FAR the largest part of the .synthetic rubber now manufactured in this country is prepared from elastomers produced by the copolymerization of butadiene and styrene, two substances called "monomers." The copolymerization is carried out under carefully controlled conditions according to GR-S recipes. These recipes require that the copolymerization should not be carried to completion; it is essential for the economic application of the process that the unreacted monomers lie recovered.