Alkyl groups definition

By definition, alkylating agents are compounds that are capable of introducing alkyl groups into nucleophilic sites on other molecules through the formation of covalent bonds. These nucleophiUc targets for alkylation include the sulfhydryl, amino, phosphate, hydroxyl. 

These Es parameters estimated by Eq. 4 for hetero atom substituents can be combined with those originally developed for various alkyl groups as a set of steric constants for QSAR studies of aromatic systems 6). Thus, apart from the original definition for the intramolecular steric effect, the combined set of Es parameters is able to represent intermolecular steric effects as well. The original Taft E, values for unsymmetrical alkyl groups seem to represent effective steric dimension of the groups which is scaled on the same standard as those for symmetric monoatomic substituents where the effective dimension coincides with the van der Waals radius. 

Perhaps the best studied group of titanium(IV) complexes is the alkoxides. The metal alkoxides generally have received a great deal of attention because of their ease of hydrolysis and reactivity with hydroxylic molecules, and their tendency to increase the coordination number of the metal which is opposed by the steric effect of the alkyl group. These properties result in materials, the characteristics of which range from polymeric solids to volatile liquids. The definitive review of this area is that by Bradley. ... 

MacPhee, J. A., A. Panaye, and J.-E. Dubois, A critical examination of the Taft steric parameter-Es. Definition of a revised, broader and homogeneous scale. Extension to highly congested alkyl groups , Tetrahedron, 34, 3553-3562 (1978). 

When K[PtX(acac)2] (X = Cl, Br) is treated with a strong proton add the uncoordinated 0,0 site is protonated and complex (170) is formed.1606,1607 If the alkyl groups on the 0,0 -bonded acac ligand are non-equivalent, exchange can be observed. Although the mechanism has not been definitively proven, a dissociative mechanism is favored.160 This proposal correlates with the observations that the 0,0 -bonded chelate complex Pt(acac)2 will react with tertiary phosphines and nitrogen bases with substitution of one of the oxygen-bonded chelate arms.1609,1610 A variety of products are formed as outlined in Scheme 17. 

Some information is available on other acrylates. N,N-disubstituted acrylamides form isotactic polymers with lithium alkyls in hydrocarbons (12). t-Butylacrylate forms crystallizable polymers with lithium-based catalysts in non-polar solvents (65) whereas the methyl, n-butyl, sec-butyl and isobutyl esters do not. Isopropylacrylate also gives isotactic polymer with lithium compounds in non-polar solvents (34). The inability of n-alkylacrylates to form crystallizable polymers may result from a requirement for a branched alkyl group for stereospecific polymerization. On the other hand lack of crystallizability cannot be taken as definite evidence of a lack of stereoregulating influence, as sometimes quite highly regular polymer fails to crystallize. The butyllithium-initiated polymers of methylmethacrylate for instance cannot be crystallized. The presence of a small amount of more random structure appears to inhibit the crystallization process1. 

Whether a C1.3 alkyl group includes lx till n-propyl and iso-propyl is a matter of claim construction and how one of ordinary skill in the art would understand such a group to mean. As we will see in the next section, the patentee can define his own terms and if he doesn t do so clearly, it is up to die court, using techniques of claim construction to figure out what is meant by definitional terms in die claims. The safest and best patent practice is for die patentee to provide die definitions in die specification to minimize any ambiguity. 

All beta hydrogen elimination occurs from the 14-electron species Cp2ZrR+ where, by definition, R is branched. In contrast, beta hydrogen elimination from Cp2ZrR,+ is slow (because the alkyl group, n-hexyl, is linear) and the rate of this reaction is taken to be zero. 

Definition A reaction whereby an alkyl group is transferred from an organometallic compound to an organic compound containing an (activated) allyl group. 

Isotestosterone and 8a, 1 Oa-testosterone can be considered as substituted testosterone derivatives where the 8-H is substituted by an alkyl group. In the case of 8a,10a-testosterone other structural features are prohibitive for biological activity. However, 8-isotestosterone displays decreased, but definite androgenic and anabolic properties. Nagata [160] prepared some 8/3-substituted testosterone homologs —8-methyl-testosterone (E-30) and others. In all cases decreased androgenic and anabolic potencies were observed. These facts point to the importance of /3-face attachment to the receptor at carbon-8. 

In spite of the fairly high densities used for the experiments on ethyl ether and propyl ether (at the lowest temperature used in the experiment the vapour pressure of ethyl ether is nearly equal to the saturation pressure), the pressure is found to obey a purely linear law. This difference of behaviour between the ethers and the chlorides is in complete agreement with K. L. Wolf s recent deductions from the dielectric properties of mixtures of liquids. In his paper Wolf attempts to explain the occurrence of association as being chiefly due to the presence of dipoles. If, as in the case of the ethers, the definitely polar parts of the molecule are sheltered by neutral alkyl groups on either side—and in this his statements are in complete agreement with our results —association phenomena will only occur to a trifling extent, whereas if the alkyl groups are terminal, as in the chlorides, marked association phenomena must occur. 

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