Highly-branched

Higher chlorides, Si2Cle to Si6Cl,4 (highly branched - some cyclic) are formed from SiCU plus Si or a silicide or by amine catalysed disproportionations of Si2Cl,5, etc. Partial hydrolysis gives oxide chlorides, e.g. CUSiOSiCla. SiCU is used for preparation of silicones. 

An essential component of cell membranes are the lipids, lecithins, or phosphatidylcholines (PC). The typical ir-a behavior shown in Fig. XV-6 is similar to that for the simple fatty-acid monolayers (see Fig. IV-16) and has been modeled theoretically [36]. Branched hydrocarbons tails tend to expand the mono-layer [38], but generally the phase behavior is described by a fluid-gel transition at the plateau [39] and a semicrystalline phase at low a. As illustrated in Fig. XV-7, the areas of the dense phase may initially be highly branched, but they anneal to a circular shape on recompression [40]. The theoretical evaluation of these shape transitions is discussed in Section IV-4F. 

By combining the basic principles of lUPAC notation with the names of the various alkyl groups we can develop systematic names for highly branched alkanes We 11 start with the following alkane name it then increase its complexity by successively adding methyl groups at various positions... 

Highly branched groups such as tert butyl are commonly described as bulky... 

Carbocation intermediates are not involved m hydroboration-oxidation Hydration of double bonds takes place without rearrangement even m alkenes as highly branched as the following... 

Amberlite LA-1 A secondary amine containing two highly branched aliphatic chains of M.W. 351 to 393. Solubility is 15 to 20 mg/mL in water. Used as 5 to 40% solutions in hydrocarbons. 

The sales brochures of the manufacturers describe the plasticizer range alcohols available on the merchant market (18). Typical properties of several commercial plasticizer range alcohols are presented in Table 8. Because in most cases these ate mixtures of isomers or alcohols with several carbon chains, the properties of a particular material can vary somewhat from manufacturer to manufacturer. Both odd and even carbon chain alcohols are available, in both linear and highly branched versions. Examples of the composition of several mixtures are given in Table 9. 

Other Dimer Olefins. Olefins for plasticizer alcohols are also produced by the dimerization of isobutene [115-11-7] 4 8 codimerization of isobutene and / -butene [25167-67-3]. These highly branched octenes lead to a highly branched isononyl alcohol [68526-84-1] product. BASE, Ruhrchemie, ICl, Nippon Oxocol, and others have used this source. 

Aerosol-Based Direct Fluorination. A technology that works on Hter and half-Hter quantities has been introduced (40—42). This new aerosol technique, which functions on principles similar to LaMar direct fluorination (Fig. 5), uses fine aerosol particle surfaces rather than copper filings to maintain a high surface area for direct fluorination. The aerosol direct fluorination technique has been shown to be effective for the synthesis of bicycHc perfluorocarbon such as perfluoroadamantane, perfluoroketones, perfluoroethers, and highly branched perfluorocarbons. 

Even alkanes, when treated with superacids, can undergo oligocondensation. Eor example, highly branched polyalkanes, of molecular weight up to 700, were obtained by treating gaseous alkanes (C —with Hquid superacids at room temperature (81). 

StmcturaHy, arabinogalactan is a complex, highly branched polymer of arabinose and galactose in a 1 6 ratio (67). It is composed of one fraction with an average molecular weight of 16,000, and one of 100,000 (68). 

Alkylthiocyanates and alkylselenocyanates are obtained by treatment of trialkylboranes with potassium thiocycanate (260) and sodium selenoisocyanate (261), in the presence of iron(III) compounds, respectively. Unsymmetrical trialkylboranes react preferentially at the more highly branched alkyl group. Alkenylphenyl selenides are obtained by the reaction of alkenylboronic acids with phenylselenyl bromide (262). 

The alkyl and alkoxy substituents of phosphate or phosphonate esters also affect the phosphorylating abiUty of the compound through steric and inductive effects. A satisfactory correlation has been developed between the quantitative measure of these effects, Tafts s O, and anticholinesterase activity as well as toxicity (33). Thus long-chain and highly branched alkyl and alkoxy groups attached to phosphoms promote high stabiUty and low biological activity. 

Highly branched fractions of nonuniformly branched resins have low molecular weights and are easily soluble, even at room temperature, in saturated hydrocarbons. These highly branched fractions are called extractables, an excessive amount of which in an LLDPE resin can be detrimental to certain end use properties, especially in food packaging appHcations. 

Within the saturates in petroleum gases and naphtha, except for a few highly branched components in the Cg—C q range, every possible paraffin from methane to normal decane is present. Depending on the source, one of the low hoiling paraffins may be the most abundant compound in a... 

Formaldehyde may react with the active hydrogens on both the urea and amine groups and therefore the polymer is probably highly branched. The amount of formaldehyde (2—4 mol per 1 mol urea), the amount and kind of polyamine (10—15%), and resin concentration are variable and hundreds of patents have been issued throughout the world. Generally, the urea, formaldehyde, polyamine, and water react at 80—100°C. The reaction may be carried out in two steps with an initial methylolation at alkaline pH, followed by condensation to the desired degree at acidic pH, or the entire reaction may be carried out under acidic conditions (63). The product is generally a symp with 25—35% soHds and is stable for up to three months. 

Silicone Resins. Sihcone resins are an unusual class of organosdoxane polymers. Unlike linear poly(siloxanes), the typical siUcone resin has a highly branched molecular stmcture. The most unique, and perhaps most usehil, characteristics of these materials are their solubiUty in organic solvents and apparent miscibility in other polymers, including siUcones. The incongmity between solubiUty and three-dimensional stmcture is caused by low molecular weight < 10, 000 g/mol) and broad polydispersivity of most sihcone resins. 

The alcohol fraction is likewise a complex mixture of both aUphatic and cycHc compounds (Table 10). The principal components are cholesterol (34%), and lanosterol and dihydrolanosterol (38%). The aUphatic alcohols account for about 22% of the unsaponifiable products. Sixty-nine components of ahphatic alcohols had been reported up to 1974 (latest reported work as of ca 1997). The hydrocarbons (ca 0.5%) show stmctural similarity to the wool—wax acids or ahphatic alcohols and contain highly branched alkanes as well as cycloalkanes. 

Alkylate. Alkylation means the chemical combination of isobutane with any one or a combination of propylene, butylenes, and amylenes to produce a mixture of highly branched paraffins that have high antiknock properties with good stabiUty. These reactions are cataly2ed by strong acids such as sulfuric or hydrofluoric acid and have been studied extensively (98—103). In the United States mostly butylenes and propylene are used as the olefins. 

Highly Branched Acids. These acids, called neoacids, are produced from highly branched olefins, carbon monoxide, and an acid catalyst such as sulfuric acid, hydrogen fluoride, or boron trifluoride. 2,2,2-Trimethylacetic acid (pivaUc acid) is made from isobutylene and neodecanoic acid is produced from propylene trimer (see Carboxylic Acids, trialkylacetic acids). 

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