C substitution in

Given the small difference in the masses of and relative to those of hydrogen and deuterium, 

ACS Symposium Series American Chemical Society Washington, DC, 1975. 

Long term experiments involving 13c substitution in mice have been attempted, with Inconclusive results on the possible deleterious effects of the isotope (38). These animals were fed on a diet of performed l c materials derived from laboratory synthesis, together with added vitamins, etc. of isotopically normal content. 

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The experiments which we used to determine the rate coefficient of the reactions of formation and decomposition of nitric oxide referred to an oxygen concentration which varied within comparatively narrow limits near 150 mm 02 at 17°C. Substituting in place of the old expression for the rate coefficient... 

The reported +46% aromaticity% (i.e., stabilization) [128] for 23 is somewhat surprising. Previously it has been reported [130] that the parent compound (with hydrogens on P and C) cannot be optimized as a four-membered ring, opening up at the PP bond, while it could be stabilized by amino (at P) and silyl (at C) substitution, in accordance with the substituent pattern of synthesized derivatives of 23 [129],... 

Compounds of noticeable chemical interest have been studied at the Stockholm University in the SCF ab initio framework. In the thiophene molecule 74>, reactive areas for electrophilic reactants have been found in the 7r region above and below the C—C double bonds and the sulphur atom (the electrons around S have a tetrahedral rather than a trigonal arrangement). The authors consider as more likely an electrophilic attack proceeding via weak intermediate addition complexes of --type and estimate the ratio of Ca/C substitution in a good agreement with experimental data. 

Electrophilic C-substitution in pyridines carrying strongly activating substituents (nitrogen and oxygen) is discussed in Sections 8.9.3.1 and 8.9.2.I. 

The only known C-substitutions in the heterocyclic rings of any benzo-azole are the 2-bromination of benzimidazole with A-bromosuccinimide, the 2-substimtion of benzothiazole with bromine at 450 °C ° and the 3-nitration of indazole." The general rnle is that electrophilic nitrations and halogenations can be achieved only in the benzene ring at the 5-, or 6- or 7-positions, for example 5-bromobenzimidazole can be obtained in high yield from the unsubstituted heterocycle." The efficient conversion of indazole into 3-iodoindazole" is achieved in the presence of base and probably involves iodination of the indazolyl anion (see 26.3). 

The analogous expression holds for component C. Substituting in the values gives... 

The reluctance to undergo electrophilic C-substitution in the five-membered ring can be overcome using silylated derivatives, as shown by the examples."... 

The B-N bond is a C-C substitute in an aromatic system (09CJC8). B-triethyl-N-o-tolylborazin (420) was among the first examples of atropi-somerism in N-aryl six-membered heterocycles. Two diastereomers were observed by NMR, one having the three methyl groups of the o-tolyl on the same face ids form) and the other having two tolyls up and one down (trans form). 

About 60 glycosides of S-rhodomycinone (39f) and other stereoisomers with sugar residues at C-7, C-10, or in both positions have been reported (see Table 5). C-substitution in ring A is scarcely observed in anthracy-cHnes exceptions are mutactimycin A (40a) and D (40b) from a Strepto-... 

Example 2. Alcohol boils at 78.4°C. What is its vapor pressure at 20°C. Substituting in equation 2 ... 

C. Substitution in the phenyl ring at the a-position raises Jg to 115 °C. Jg in the case of a naphthalene substitution has a value of 135 °C. Jg for biphenyl is 145 °C. Tg of the more sterically hindered poly(a-methylstyrene) is 175 °C and that of polyacenaphthalene is 265 °C. A further illustration of the influence of subtle changes on T g can be seen in the case of poly(butyl methacrylate)s. The normal butyl methacrylate has a T g value of 56 °C, that of secondary butyl methacrylate is 22 °C and that of isobutyl methyacrylate is 43 °C. Once more, the greater the steric interaction the higher the value of T g. 

The competition between N- and C-substitution in the alkali metal derivatives of pyrrole is, of course, only one example of the general problem of substitution into ambident ions 225-26 ... 

The formulation of the pyrrole Grignard reagents as ionic, but not highly dissociated, structures related to (104) enables the predominant C-substi-tution reactions to be formulated in the same way as the similar processes leading to C-substitution in the alkenylation of other metallic derivatives of pyrrole (p. 67). The reagents should be regarded as sources of more or less dissociated ambident pyrrole anions (p. 68). 

Here, indicates the derivative with respect to C- Substituting in the governing equation. 

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