Other Precursors

Melt processable acrylic such as BP Amoco Lima Chemicals Barex, an AN-MA copol5mer, which can be extruded and Amlon, with a high AN content have been melt spun [279]. Aromatic hydrocarbons 

Carbon fibers can be prepared from aromatic hydrocarbons [280] and carbon can be deposited onto a polymer fiber by the pyrolysis of benzene to give a CCVD fiber [281]. 

Carbon fibers can be produced from a non-polymeric hydrocarbon extract from coal and the addition of up to 20% of an amine-amide-alcohol or a carboxylic acid with no aromatic groups and at least eight carbon atoms, enables the extrusion of fibers [282]. The viscosity 

Source Reprinted with permission from Lewis 1C, Singer LS, Preprints of Fuel Div, Am Chem Soc, 13, 86,1969. Copyright 1969, American Chemical Society. 

Reprinted with permission from Zimmer JE, White JL, Disclination structures in the carbonaceous mesophase, Advin LiqCrysts, 5, Academic Press, New York, 157,1982. Copyright 1982, Elsevier. 

---

This phosphinic anhydride [15171 -48-9] C H O P, is then reacted with glycol and other precursors of poly(ethylene terephthalate), to produce a flame-retardant polyester [82690-14-0] having phosphinate units of the stmcture —0P(0)(CH2)CH2CH2C00—. Trevira 271 is useflil for children s sleepwear, work clothing, and home flirnishings. A phosphoms content as low as 0.6% is reported to be sufficient for draperies and upholstery tests if melt-drip is not retarded by print pigments or the presence of nonthermoplastic fibers (28). 

However, the preparation of l-nitroanthraquiQone-2-carboxyhc acid has the difficulties mentioned previously. Therefore, new processes for preparing this compound not from the 1-nitro compound but from other precursors have been iatensively studied. 1-Amin oanthra quin one derivatives have been proposed for this purpose (90). 

Among the most logical disconnections of the carbocyclic rings of 272 (or the other precursors shown extending to 278) is that involving the strategic C(4)-C(5), C(6)-0 bond pair in 272 - 278. 

On the other hand, organic materials of relatively low molecular weight such as acetylene, benzene, ethylene and methane, can produce vapour-grown carbon materials by imperfect combustion or by exposing their vapour to a heated substrate in an electric furnace in the presence of a metal catalyst. The latter process generates VGCFs. Other precursors to VGCF include polyacrylonitrile (PAN), isotropic or mesophase pitch, rayon or nylon [8]. 

The TCO is synthesized from SnO, B203, Sn2P207, A1203, and other precursors. The nature of the insertion mechanism of lithium into the Fuji material has... 

Processing. The process requires a monofilament carbon-fiber core which is heated resistively in a tubular glass reactor shown schematically in Fig. 19.1. PI A carbon monofilament is pre-coated with a 1 pm layer of pyrolytic graphite to insure a smooth deposition surface and a constant resistivity. 1 1 SiC is then deposited by the reaction of silane and a hydrocarbon. Other precursors such as SiCl4, and CH3SiCl3 are also being investigated. A fiber cross-section is shown in Fig. 19.2.P1... 

CO is the precursor of the carbonyl group of acetyl-CoA (discussed earlier). An identical EPR signal is observed when other precursors of the carbonyl group of acetyl-CoA are reacted with CODH/ACS for example, CO2 in the presence of reductant 145) and pyruvate 164). Incubation with acetyl-CoA itself also gives rise to this EPR signal 185). 

Associated to copper(II) pre-catalysts, bis(oxazolines) also allowed the asymmetric Diels-Alder and hetero Diels-Alder transformations to be achieved in nearly quantitative yield and high diastereo- and enantioselectivities. Optically active sulfoximines, with their nitrogen-coordinating site located at close proximity to the stereogenic sulfur atom, have also proven their efficiency as copper ligands for these asymmetric cycloadditions. Other precursors for this Lewis acid-catalyzed transformation have been described (e.g., zinc salts, ruthenium derivatives, or rare earth complexes) which, when associated to bis(oxazolines), pyridine-oxazolines or pyridine-bis(oxazolines), led to efficient catalysts. 

The catalysts had to be free of residual impurities such as chloride ions, nitrates, solvent, or other precursor species. 

Other studies showed the same trends discussed earlier. Films obtained by RF-PECVD, deposited at about the same conditions in other precursor atmospheres [79], showed the same behavior, with the Id/Iq and wq following about the same dependence on nitrogen content as the one shown in Figure 23. 

Preussmann, R., Angew. Chem., 1963, 75, 642 Removal of the solvent carbon tetrachloride (in which nitrosation had been effected) at ambient, rather than reduced, pressure caused a violent explosion at the end of distillation. Lowest possible temperatures should be maintained in the preparation. Other precursors seem more suitable as sources of diazomethane. 

In the sixth paper of this chapter, Kierzek et al., mainly focus on modeling of pore formation vs surface area growth phenomena upon activation of coal and pitch-derived carbon precursors. These authors briefly touch on other precursor carbons as well. The properties of newly synthesized materials are being looked at from the point of view of their application as active materials in the supercapacitor electrodes. Editors thought this work by the Institute of Chemistiy and Technology of Petroleum and Coal in Poland, could be of genuine interest to the practical developers of carbon materials for the supercapacitor industry. 

Attempts to prepare 1 from some other precursors were largely unsuccessful N, N , A,/-(cyclopropane-l,2,3-trimethyl)-tris(dimethylamine oxide) decomposed unspecifically above 250 °C3 and pyrolysis of l,2,3-tris(acetoxymethyl)cyclopropane gave mainly benzene3 its gas-phase pyrolysis at 570-580°C produced a mixture of at least fifteen compounds containing perhaps a small amount of l7. 

As shown by Breslow et al. during the mid-1960s, most transition-metal alkox-ide or acetylacetonate complexes catalyze the hydrogenation of alkenes in the presence of an activator (Table 6.19) [5]. Other precursors have been used such as [CpCr(CO)3]2, but it is more difficult to understand how the active species are formed [133]. 

For example, rater 1 rated that 27 precursors had an effective observation. However, rater 2 rated that only 23 precursors had an effective observation and that one precursor had an ineffective observation and the three other precursors had an ineffective steering, causing an ineffective observation. 

Functionalization of polysilanes by chemical modification (post-polymerization) was covered in COMC II (1995) (chapter Organopolysilanes, p 101), where the formation of precursor polysilanes with potentially functionalizable side groups such as chloride, type 34 (via HCI/AICI3 chlorodephenylation of PMPS), 6 triflate, type 35 (via triflate replacement of phenyl groups)135,137 or alkyl halide (via chloromethylation of phenyl groups,138,139 type 36, or addition of HC1 or HBr to double bonds140) was discussed. Four other precursor polysilanes, which utilize the reactivity of the Si-Cl or Si-H bond, have been successfully applied in functionalization since COMC (1995) perchloropolysilane, 17 (see Section 3.11.4.2.2.(i) for synthesis),103 poly[methyl(H)silylene-f >-methylphenylsilylene],... 

For the performance of intermolecular reactions of 5, its generation from the sodium salt of tropone tosylhydrazone (517) and from halo-1,3,5-cydoheptatrienes (518) are most suitable, but other precursors can also be employed, as illustrated in Scheme 6.105. In view of the product structures, some reactions of 5 give results that deviate from those of typical allene processes, and this is even valid for the dimerization (Scheme 6.105). 

The formation of gaseous organic cations under electron bombardment of alkanes, haloalkanes and other precursors has been widely investigated in mass spectral studies (Field and Franklin, 1957 McLafiFerty, 1963). 

The development of nylon by DuPont in 1938 generated the initial big commercial interest in cyclohexane as they settled on its use as their preferred raw material. In the period right after World War II, the manufacture of nylon grew for a while at 100% annually, quickly overwhelming the availability of cyclohexane naturally available in crude oil. The typical crude oil processed in U.S. refineries at the time had less than 1% content of cyclohexane. Ironically, since cyclohexane leaves the crude oil distillation operation in the naphtha, it was usually fed to a cat reformer, where it was converted to henzene. As it turned out, with so many other precursors also being converted to benzene in the cat reformer, benzene became a good source for cyclohexane manufacture. 

The chief precursors for both oxidant and suspended particulate matter formation in the atmosphere, which are directly emitted into the atmosphere, are nitrogen oxides, hydrocarbons and their derivatives, ammonia, and sulfur dioxide. The measurement of particulate components is discussed in Chapter 2. This section describes briefly the measurement of nitrogen oxides, hydrocarbons, free radicals, and other precursors. 

The reaction is catalyzed by palladium complexes either pre-formed, as [Pd(TPPMS)3] [13], or prepared in situ from (usually) [Pd(OAc)2] and various phosphines [21,23-27], TPPTS being one of the most frequently used [14]. Other precursors, e.g. [ PdCl(T -C3H5) 2] and so-caUed ligandless (phosphine-free) Pd-catalysts can also be effective. In fact, in several cases a phosphine inhibition was observed [23]. The solvent can be only slightly aqueous (5 % water in CH3CN, [14]) or neat water [26]. In the latter case a biphasic reaction mixture (e.g. with toluene) facilitates catalyst separation albeit on the expense of the reaction rate. A short selection of the reactions studied in aqueous solvents is shown on Scheme 6.9. 

Adachi and Oka investigated the formation of cyanide during the reaction of chlorine with 20 different pharmaceuticals containing nitrogen in their molecular structure [90]. High levels of cyanide were generated by chlorination of hexamine and losartan potassium aqueous solutions. Other precursors of cyanide included metronidazol, dacarbazine, and allopurinol. 

---