Molecular branched chain

Two constitutionally isomeric alkanes have the molecular formula C4H10 One has an unbranched chain (CH3CH2CH2CH3) and is called n butane, the other has a branched chain [(CH3)3CH] and is called isobutane Both n butane and isobutane are common names... 

Inhalation of aerosols or heated vapors may result in irritation of the nose, throat, and upper respiratory system. Lower molecular weight and branched-chain amines are more volatile and can cause irritation if inhaled. Volatile amines are easily recognized by their unpleasant, fishy odor. 

Thiuram Sulfides. These compounds, (8) and (9), are an important class of accelerator. Thiurams are produced by the oxidation of sodium dithiocarbamates. The di- and polysulfides can donate one or more atoms of sulfur from their molecular stmcture for vulcanization. The use of these compounds at relatively high levels with litde or no elemental sulfur provides articles with improved heat resistance. The short-chain (methyl and ethyl) thiurams and dithiocarbamates ate priced 2/kg. Producers have introduced ultra-accelerators based on longer-chain and branched-chain amines that are less volatile and less toxic. This development is also motivated by a desire to rninirnize airborne nitrosamines. 

Branched-chain acid (common name) CAS Registry Number Molecular weight Boiling point, °C Melting point, °C Approximate price, [kR Producers in the United States... 

The hazards of handling branched-chain acids are similar to those encountered with other aliphatic acids of the same molecular weight. Eye and skin contact as well as inhalation of vapors of the shorter-chain acids should be avoided. 

Properties are furthermore determined by the nature of the organic acid, the type of metal and its concentration, the presence of solvent and additives, and the method of manufacture. Higher melting points are characteristics of soaps made of high molecular-weight, straight-chain, saturated fatty acids. Branched-chain unsaturated fatty acids form soaps with lower melting points. Table 1 Hsts the properties of some soHd metal soaps. 

Linear polymers are the most commonly found, and consist of chains of D units endblocked by a variety of functionalized M units. Branched-chain silicones consist mainly of D units, with a D unit being replaced by a T or a Q unit at each point of branching. Cyclic PDMS oligomers are also common and can play a role in adhesion. They are usually found as mixtures of structures going from three siloxy units, to four, five, and higher siloxy units. A whole range of analytical techniques can determine the detailed molecular structures of these materials [20,21],... 

The ability of C to catenate (i.e. to form bonds to itself in compounds) is nowhere better illustrated than in the compounds it forms with H. Hydrocarbons occur in great variety in petroleum deposits and elsewhere, and form various homologous series in which the C atoms are linked into chains, branched chains and rings. The study of these compounds and their derivatives forms the subject of organic chemistry and is fully discussed in the many textbooks and treatises on that subject. The matter is further considered on p. 374 in relation to the much smaller ability of other Group 14 elements to form such catenated compounds. Methane, CH4, is the archetype of tetrahedral coordination in molecular compounds some of its properties are listed in Table 8.4 where they are compared with those of the... 

Two different alkanes are known with the molecular formula C Hm- In one of these, called butane, the four carbon atoms are linked in a straight (unbranched) chain. In the other, called 2-methylpropane, there is a branched chain. The longest chain in the molecule contains three carbon atoms there is a CH3 branch from the central carbon atom. The geometries of these molecules are shown in Figure 22.2 (p. 581). The structures are... 

How can there be so many compounds containing this one element The answer lies in the molecular structures. We shall find that carbon atoms have an exceptional tendency to form covalent bonds to other carbon atoms, forming long chains, branched chains, and rings of atoms. Each different atomic arrangement gives a mole-... 

The solubility of several salts of alkyl esters of a-sulfopalmitic acid and a-sulfostearic acid was measured by Stirton et al. [30]. The aqueous solubility of the a-sulfopalmitates is better than the solubility of the a-sulfostearates and it also increases with increasing molecular weight of the alcohol. The same dependency is found in organic solvents, such as chloroform ethanol, petroleum ether diethyl ether, and mineral oil. They also showed that esters of secondary and branched chain alcohols are more soluble than esters of normal primary alcohols. 

In the case of amphiphilic molecules, characterized by the coexistence of spatially separated apolar (alkyl chains) and polar moieties, both parts cooperate to drive the intermolecular aggregation. This simple but pivotal peculiarity makes amphiphilic molecules soluble in both polar and apolar solvents and able to realize, in suitable conditions, an impressive variety of molecular aggregates characterized by spatially separated apolar and polar domains, local order at short times and fluidity at long times, and differences in size, shape (linear or branched chains, cyclic or globular aggregates, extended fractal-like molecular networks), and lifetime. 

Figure 13-13. The glycogen molecule. A General structure. B Enlargement of structure at a branch point. The molecule is a sphere approximately 21 nm in diameter that can be visualized in electron micrographs. It has a molecular mass of 10 Da and consists of polysaccharide chains each containing about 13 glucose residues. The chains are either branched or unbranched and are arranged in 12 concentric layers (only four are shown in the figure). The branched chains (each has two branches) are found in the inner layers and the unbranched chains in the outer layer. (G, glycogenin, the primer molecule for glycogen synthesis.)...

Harris RA et al Molecular cloning of the branched-chain a-ke-toacid dehydrogenase kinase and the CoA-dependent methyl-... 

Most small olefins produced in the chemical industry are used to make polymers, with a global production of the order of 100 million tons per year. Polymers are macromolecules with molecular weights of typically lO" to 10 and consist of linear or branched chains, or networks built up from small monomers such as ethylene, propylene, vinyl chloride, styrene, etc. The vast majority of polymers are made in catalytic processes. Here we concentrate on ethylene polymerization over chromium catalysts as an example [M.P. McDaniel, Adv. Catal. 33 (1985) 47]. 

Molecular Sieve 5A n-Alkanes and other straight-chain molecules in the presence of branched chain molecules. 

Arts. These compounds can each form isomers (having the same molecular formulas). C4H,0 can occur as a straight-chain compound and a branched-chain compound. C3H6 can occur with a double bond or in a ring. 

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