By boron compounds

Hydrocarbon Oxidation. The oxidation of hydrocarbons (qv) and hydrocarbon derivatives can be significantly altered by boron compounds. Several large-scale commercial processes, such as the oxidation of cyclohexane to a cyclohexanol—cyclohexanone mixture in nylon manufacture, are based on boron compounds (see Cylcohexanoland cyclohexanone Eibers, polyamide). A number of patents have been issued on the use of borate esters and boroxines in hydrocarbon oxidation reactions, but commercial processes apparently use boric acid as the preferred boron source. The Hterature in this field has been covered through 1967 (47). Since that time the Hterature consists of foreign patents, but no significant appHcations have been reported for borate esters. 

Linear polyethylene can further also be considered as polymethylene. Althoguh first prepared by the thermal decomposition of diazomethane,243 244 Meerwein should be credited to have prepared it by catalytic polymerization of diazomethane effected by boron compounds (esters, halides, alkyls)245-247 taking place with concomitant dediazotation ... 

Some of the more active catalysts for the polymerization of styrene are shown in Figure 22.17. Monocyclopentadienyltitanium halides, such as CpTiXj, CpTiXj, and CpTiXj, in combination with MAO, were more active catalysts than simple tetrahalides. Of these Cp-ligated trihalide complexes, the fluoride complexes were most active, followed by alkoxides and then chlorides. Moreover, cyclopentadienyl-ligated alkyltitanium compounds, such as Cp TiRj (R = hydrocarbyl) activated by boron compounds B(C Fj)j... 

Bawn, C.E.H., Led with, A., and Matthies, P. (1959) The mechanism of the polymerization of diazoalkanes catalyzed by boron compounds. Journal of Polymer Science, 34,93-108. 

The melting and boiling points of the aluminium halides, in contrast to the boron compounds, are irregular. It might reasonably be expected that aluminium, being a more metallic element than boron, would form an ionic fluoride and indeed the fact that it remains solid until 1564 K. when it sublimes, would tend to confirm this, although it should not be concluded that the fluoride is, therefore, wholly ionic. The crystal structure is such that each aluminium has a coordination number of six, being surrounded by six fluoride ions. 

Ar. Buraq, Pers. Burah) Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. 

By far the most commercially important boron compound in terms of dollar sales is Na2B407.5H20. This pentahydrate is used in very large quantities in the manufacture of insulation fiberglass and sodium perborate bleach. 

The names of addition compounds are formed by connecting the names of individual compounds by a dash (—) and indicating the numbers of molecules in the name by Arabic numerals separated by the solidus (diagonal slash). All molecules are cited in order of increasing number those having the same number are cited in alphabetic order. However, boron compounds and water are always cited last and in that order. 

Heating triacetylboron at temperatures above its melting poiat, 123°C, causes a rearrangement to B20(0CCH2)4 (15). An explosive hazard is also generated by dissolving BF ia anhydride (see Boron compounds). 

Boron trifluoride [7637-07-2] (trifluoroborane), BF, was first reported in 1809 by Gay-Lussac and Thenard (1) who prepared it by the reaction of boric acid and fluorspar at duU red heat. It is a colorless gas when dry, but fumes in the presence of moisture yielding a dense white smoke of irritating, pungent odor. It is widely used as an acid catalyst (2) for many types of organic reactions, especially for the production of polymer and petroleum (qv) products. The gas was first produced commercially in 1936 by the Harshaw Chemical Co. (see also Boron COMPOUNDS). 

Manufacture, Shipping, and Waste Treatment. Fluoroboric acid (48%) is made commercially by direct reaction of 70% hydroduoric acid and boric acid, H BO (see Boron compounds). The reaction is exothermic and must be controlled by cooling. 

For the most part boric acid esters are quantitated by hydrolysis in hot water followed by determination of the amount of boron by the mannitol titration (see Boron compounds, boric oxide, boric acid and borates). Separation of and measuring mixtures of borate esters can be difficult. Any water present causes hydrolysis and in mixtures, as a result of transesterification, it is possible to have a number of borate esters present. For some borate esters, such as triethanolamine borate, hydrolysis is sufftciendy slow that quantitation by hydrolysis and titration cannot be done. In these cases, a sodium carbonate fusion is necessary. 

Boron Hydrides" under "Boron Compounds" in ECT 1st ed., Vol. 2, pp. 593—600, by S. H. Bauer, Cornell University "Boron Hydrides and Related Compounds" under "Boron Compounds," Suppl. 1, pp. 103—130, by S. H. Bauer, Cornell University "Diborane and Higher Boron Hydrides" under "Boron Compounds," Suppl. 2, pp. 109—113, by W. J. Shepherd and E. B. Ayres, Gallery Chemical Company "Boron Hydrides" under "Boron Compounds" in ECT 2nd ed., Vol. 3, pp. 684—706, by G. W. Campbell, Jr., U.S. Borax Research Corporation "Boron Hydrides and their MetaHo Derivatives" under "Boron Compounds," in ECT 3rd ed., Vol. 4, pp. 135—183, by R. W. Rudolph, The University of Michigan. 

Boron Compounds (Boron Hydrides)" in ECT 1st ed., Vol. 2, pp. 593—600, "Boron Compounds (Boron Hydride and Related Compounds)" Suppl. 1, pp. 103—130, by S. H. Bauer, Cornell University "Boron Compounds (Diborane and Higher Boron Hydrides)" Suppl. 2, pp. 109—113, byj. W. Shepherd and... 

Research Corp. "Boron Compounds (Boron Hydrides, Commercial Aspects)" in ECT3rd ed., Vol. 4, pp. 183—187, by G. B. Dunks, Union Carbide Corp. 

Another type of anion, confined for practical purposes to boron compounds, has no unshared electrons at the anionic site, and must be thought of as being formed by addition of hydride to a boron atom (or other atom with an incomplete valence shell). Such structures were not anticipated at the time general heterocyclic nomenclature was developed, and they are only recently being fitted into systematic nomenclature (lUPAC Provisional Recommendation 83.2). Proposals for a suffix to indicate such structures are under consideration (1982). 

A scram causes the control rods to drop into the core, absorb neutrons and stop the chain reaction. Some rods perform both controlling and scram functions. The control rods are raised to increase the neutron flux (and power) or lowered to reduce it by magnetic jacks (W and CE) or a magnetic "clamshell" screw (B W). The chemical volume and control system (CVCS - not siiown) controls the water quality, removes radioactivity, and varies the reactivity by controUing the amount of a boron compound that is dissolved in the water - called a "poison." Thus, a PWR coiiirols reactivity two ways by the amount of poison in the water and by moving the control rods. 

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