Alkylation single bonds

It follows from this that where there is equal population of all conformers in an alkyl group (free rotation about the CC single bond) then an averaged coupling constant Jqh = syn + / 3 of... 

Although these reactions are thus closely related to the acyl-alkyl diradical disproportionation to ketenes, the stereospecificity of (55) -> (56) and (57) -> (58) shows that these hydroxyketones cannot proceed through free radicals capable of rotating about single bonds prior to the intramolecular hydrogen... 

Replacing an a-alkyl snbstituent by an a-aryl group is expected to stabilize the cationic center by the p-Jt resonance that characterizes the benzyl carbocations. In order to analyze such interaction in detail, the cumyl cation was crystallized with hexafluoroantimonate by Laube et al. (Fig. 13) A simple analysis of cumyl cation suggests the potential contributions of aromatic delocalization (Scheme 7.3), which should be manifested in the X-ray structure in terms of a shortened cationic carbon—aromatic carbon bond distance (C Cat). Similarly, one should also consider the potential role of o-CH hyperconjugation, primarily observable in terms of shortened CH3 distances. Notably, it was found experimentally that the Cai distance is indeed shortened to a value of 1.41 A, which is between those of typical sp -sp single bonds (1.51 A) and sp -sp double bonds (1.32 A). In the meantime, a C -CH3 distance of 1.49 A is longer than that observed in the tert-butyl cation 1 (1.44 A), and very close to the normal value for an sp -sp single bond. 

Push-spectator carbenes of the type 31 (R, R = alkyl) were synthesized and reacted with various Lewis Acids to compare the reactivity of the phosphorus and carbene centers. Two such reactions are shown in Scheme 7.11. From an X-ray structural analysis, the phosphorus substituent was shown to act as a spectator, leaving its lone pair available to react in a Lewis basic manner. When carbene 31 was reacted with BF3, only the carbene adduct 32 was formed. By contrast, when 31 was reacted with the softer Lewis Acid BH3, it was the phosphorus that reacted to yield adduct 33. These types of carbenes exhibited C-NMR shifts in the range of 320-348 ppm, a P-C-N angle of 116.5° a short C-N distance of 1.296 A, and a long C-P distance of 1.856 A. The latter is very similar to that of a typical C-P single bond. 

The formation of carbon-oxygen single bonds via the attack of an alkoxide on an alkyl halide, (Williamson ether synthesis) is an extremely important reaction that... 

In a covalent single bond between unlike atoms, the electron pair forming the a bond is never shared absolutely equally between the two atoms it tends to be attracted a little more towards the more electronegative atom of the two. Thus in an alkyl chloride (20), the... 

The Prins cyclization can also be coupled with a ring-contraction pinacol rearrangement, as illustrated in Scheme 1.6. This allows a smooth conversion of alkyl-idene-cyclohexane acetal 1-16 to single bond-joined cyclohexane cyclopentane aldehyde 1-17 [le]. 

Describe the bonding that causes the P-O distance in OPR3 (R = alkyl group) to be somewhat shorter than the usual single bond length. 

The functionalization reaction as shown in Scheme 1(A) clearly requires the breaking of a C-H bond at some point in the reaction sequence. This step is most difficult to achieve for R = alkyl as both the heterolytic and homolytic C-H bond dissociation energies are high. For example, the pKa of methane is estimated to be ca. 48 (6,7). Bond heterolysis, thus, hardly appears feasible. C-H bond homolysis also appears difficult, since the C-H bonds of alkanes are among the strongest single bonds in nature. This is particularly true for primary carbons and for methane, where the radicals which would result from homolysis are not stabilized. The bond energy (homolytic dissociation enthalpy at 25 °C) of methane is 105 kcal/mol (8). 

This group of compounds includes those monomers with one or more carbon atoms carrying a hydroperoxy or peroxy group, and also singly bonded to an oxygen atom present as hydroxyl, ether or cyclic ether functions. While the group of compounds is, in general, moderately stable, the lower 1-hydroxy and 1,T-dihydroxy-alkyl peroxides or hydroperoxides are explosive. Individually indexed compounds are ... 

If the initial intermediate or the original fuel is a large monoolefin, the radicals will abstract H from those carbon atoms that are singly bonded because the CH bond strengths of doubly bonded carbons are large (see Appendix D). Thus, the evidence [12, 32] is building that, during oxidation, all nonaromatic hydrocarbons primarily form ethene and propene (and some butene and isobutene) and that the oxidative attack that eventually leads to CO is almost solely from these small intermediates. Thus the study of ethene oxidation is crucially important for all alkyl hydrocarbons. 

Alcohols, alkyl halides, ethers, and amines all have functional groups with single bonds. These compounds have many interesting uses in daily life. As you learn how to identify and name these compounds, think about how the intermolecular forces between their molecules affect their properties and uses. 

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