Molecule chain length

The equation (8) is based on the two ideas, (a) The negative deviation is due to the limitation of the particle size to carbon chain growth, (b) A simple linear relationship exists between the metal particle size and maximum molecule chain length formed on it. So.the results confirm the viewpoint that for FT synthesis on the catalysts with highly dispersion,the negative deviation is the result of cut-off effect of the small particle or crystallites size.The results also confirm the assumption that the maximum product chain length depends on the particle size linearly. 

Leong YK. (2007). Particle bridging in dispersions by small charged molecules chain length and rigidity, architecture and functional groups spatial position. Phys Chem Chem Phys, 9, 5608-5618. 

Principle of controlled radical polymerization (CRP) exemplified via nitroxide-mediated polymerization (NMP). X, nitroxide R,-, living polymer molecule P,+y, dead polymer molecule R (, dormant polymer molecule /, chain length RqX, NMP initiator activation kj a, deactivation /c2, propagation /ctc, termination by recombination (Fig. 10.5A) (Malmstrom and Hawker, 1998) for simplicity the activation/deactivation rate coefficients of the initiator species are assumed the same as... 

Molecule Chain length Functional group Name... 

This form is obeyed fairly well above x values of 5-10 dyn/cm in Fig. Ill-15c. Limiting areas or a values of about 22 per molecule result, nearly independent of chain length, as would be expected if the molecules assume a final orientation that is perpendicular to the surface. Larger A values are found for longer-chain surfactants, such as sodium dodecyl sulfate, and this has been attributed to the hydrocarbon tails having a variety of conformations [127]. 

Linear polyethers derived from three or more molecules of aliphatic dihydroxy compounds, particularly when the chain length exceeds ten units, are most conveniently named by open-chain replacement nomenclature. For example, CH3CH2—O—CH2CH2—O—CH2CH3 could be 3,6-dioxaoctane or (2-ethoxy)ethoxyethane. 

One of the most sensitive tests of the dependence of chemical reactivity on the size of the reacting molecules is the comparison of the rates of reaction for compounds which are members of a homologous series with different chain lengths. Studies by Flory and others on the rates of esterification and saponification of esters were the first investigations conducted to clarify the dependence of reactivity on molecular size. The rate constants for these reactions are observed to converge quite rapidly to a constant value which is independent of molecular size, after an initial dependence on molecular size for small molecules. The effect is reminiscent of the discussion on the uniqueness of end groups in connection with Example 1.1. In the esterification of carboxylic acids, for example, the rate constants are different for acetic, propionic, and butyric acids, but constant for carboxyUc acids with 4-18 carbon atoms. This observation on nonpolymeric compounds has been generalized to apply to polymerization reactions as well. The latter are subject to several complications which are not involved in the study of simple model compounds, but when these complications are properly considered, the independence of reactivity on molecular size has been repeatedly verified. 

Urea has the remarkable property of forming crystalline complexes or adducts with straight-chain organic compounds. These crystalline complexes consist of a hoUow channel, formed by the crystallized urea molecules, in which the hydrocarbon is completely occluded. Such compounds are known as clathrates. The type of hydrocarbon occluded, on the basis of its chain length, is determined by the temperature at which the clathrate is formed. This property of urea clathrates is widely used in the petroleum-refining industry for the production of jet aviation fuels (see Aviation and other gas-TURBINE fuels) and for dewaxing of lubricant oils (see also Petroleum, refinery processes). The clathrates are broken down by simply dissolving urea in water or in alcohol. 

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