Methyl ions

In the Wilson matrix analysis, the normal vibrational modes in methyl radical were assumed to be the same as those in both methyl ions. This assumption is rather crude however, it is believed to influence the results very little. The following values for the normal vibrational modes were obtained (in cm" ) 3100 3100 2915 1620 1620 1030. 

If the H3 ion reacts with atomic carbon, an analogous series of reactions leads to the methyl ion, CH3, although the initial reaction to form CH+ has not been studied in the laboratory. The methyl ion does not react rapidly with H2 but does undergo a relatively slow radiative association reaction,... 

Step 3 It illustrates the interaction between the solvated proton and the methylated ion. 

Zoltewicz and Oestreich (1973) employed sodium methylate to accelerate the reaction between 4-bromo-iso-quinoline and sodium thiophenolate. In this case, the CHjO ion acts as a competing electron donor with respect to the PhS ion. On electron transfer to the substrate, thiophenolate converts into the phenylthiyl radical and then to diphenyldisulhde. Diphenyldisulfide is inactive in further transformations. The methylate ions generate the anion-radicals of the substrate, thus preserving the greater part of the thiophenolate for use in substitution. The observed rate of thioarylation and the yield of 4-phenylthio-iso-quinoline increase in the presence of sodium methylate. Azobenzene inhibits the action of sodium methylate. Scheme 5.7 summarizes what has been mentioned. 

It is important to note that sodium methylate initiates only the formation of 4-phenylthio-iso-quinoline the product of the competing substitution, 4-methoxy-iso-quinoline, is produced only in traces. The methylate ion, however, converts a part of the iso-quinolyl a-radicals into the unsubstituted iso-quinoline and produces formaldehyde. 

The interaction with an adjacent cationic center has a similar character and, here again, cyclopropane has been found to be much more effective than cyclobutane. This may be seen in a comparison of the cyclopropyldimethylmethyl ion 11 with the corresponding cyclobutyl-methyl ion 12.6 8... 

Molecular orbital calculations suggest that for the parent ion and for methylated ions, 78 and 79, the bisected cyclopropylcarbinyl structure is the structure of lowest energy.93 They also predict that the cyclopropylcarbinyl-... 

A different way to determine the steric size of various silyl groups is to use the values of cone angle 6>100, which are listed in equation 817. It illustrates the mechanism of addition of the (p-anisyl)phenyl methyl ion (11) to allylsilanes101. The rate of addition depends on the size of the silyl groups. Bulky silyl groups, the size of which is reflected by their 0 values can accelerate the addition process. Given the 0 values, the size of the silyl groups follows the order shown in entry 6 of Table 1. 

Attempts have been made to prepare sterically highly crowded tertiary cations (see later discussion). The possibly most hindered trialkylmethyl cation, the tris(l-ada-mantyl)methyl ion 22, has been prepared from the corresponding chloride118 [Eq. (3.9)]. Proton loss is not favored in this case because this would lead to the formation of a bridgehead alkene. Consequently, cation 22 could be observed as a persistent, long-lived cation. 

Stable fluorinated bis(alkoxy)methyl cations 324 and tris(alkoxy)methyl ion 325 were prepared reacting the corresponding difluoroformals and fluoroorthoester with... 

It was suggested by first Smith and Adams (1978) and then Huntress and Mitchell (1979) that radiative association reactions involving the methyl ion CH (synthesized via Reaction 3.20) and a host of small neutral species could lead to a variety of more complex ion precursors to organic molecules. The rate coefficients of these radiative association reactions have since been calculated by Bates (1983) and Herbst (1980a, b 1985 a, c). Let us consider some of these reactions and the subsequent dissociative recombination reactions ... 

The electroinduced substitution of 4-chloropyridine with 2,6-dialkylphenoxide (alkyl = pentyl, isopropyl, methyl) ions was performed in a mixture of ammonia with THF254. The yields of products were lower than that obtained with 185 and they decreased when the steric hindrance of the substituents decreased and when the EWG character increased. 

The methyl ions that dissociate release neutral H or H2, yielding and CHJ ions, whose combined abundances far exceed that of the H+ ions. The loss of ionized He+ is also a rather unlikely event and takes... 

Methane-14 was prepared (Ciranni and Guarino, 1966) from aluminium carbide and pure T2O. The crude CT4, specific activity of 116,500 Curies per mole, was immediately diluted with a large excess of CH4 and subjected to a rigorous purification, including a preparative gas-chromatographic separation over a special capillary column that allows (Bruner and Cartoni, 1965) the complete resolution of the four tritiated methanes, from CH3T to CT4. The final sample, whose isotopic purity is illustrated in Fig. 5, was further diluted with CH4 to a specific activity of 0-2 Curies per mole to carry out the decay experiments. Nefedov et al. (1968) used CT4 prepared by essentially the same procedure in their study of the reactions of methyl ions in hydroxylic compounds. 

C. Reactions of Carbonium Ions in the Oas Phase at Normal Pressure 1. Reactions of CT ions with alkanes The reactions of tritiated methyl ions from the decay of methane-<4 were investigated in pure CH4, and in mixtures of CH4 and CaHg by Cacace et al. (1966), whose results are illustrated in Table 12. It was... 

Reactions (8) to (10) not only explain qualitatively the formation of the three major products, but allow a rough evaluation of the abundance of labeled methyl ions former", from the decay. Assuming, in the absence of more detailed information, a statistical distribution of tritium between the products of reaction (9), the activity of HT from reaction (9) is equivalent to 2/5 of the activity contained in the ethyl ions, eventually isolated as tritiated ethane. Therefore, the yield of HT from reaction (9) can be calculated to be 7-0 x 2/5 = 2-8%, and the fraction of the methyl ion undergoing reaction (9), 9-8%. Comparing this figure with the fraction (78%) of labeled methyl ions that react with CgHg to yield... 

Processes similar to reactions (8) and (9) have in fact repeatedly been found in the ion source of the mass spectrometer (Lampe and Field, 1959 Derwish et al., 1964a, b Field eiaZ., 1964 Munson and Field, 1964 Haynes and Kebarle, 1966). In particular, it is generally agreed that the reaction of methyl ions with CH4 leads to the exclusive formation of ethyl ions, and the C2H ions observed in early experiments are currently ascribed to the presence of impurities in the methane (Field and Munson, 1965). 

Reactions of gaseous methyl ions with water and alcohols An interesting study on the reactions of methyl ions with water, methanol and ethanol was reported by Nefedov et al. (1968), who employed CTJ ions formed from the decay of CT4. Methane- 4, prepared according to the method described by Ciranni and Guarino (1966), was allowed to decay at room temperature, in the presence of water, methanol, and ethanol, at a pressure of 20, 96 and 40 torr respectively. 

As to the reaction of methyl ions with methanol, Aquilanti et al. (1966), Koch and Lindholm (1961), Wilmenius and Lindholm (1962) and Lindholm and Wilmenius (1963), concur in the conclusion that their predominant reaction mode is represented by the hydride-ion transfer from methanol ... 

The methyl ions from the dissociation process (43a) react with methane forming tritiated ethyl ions which are completely unreactive towards methane, as discussed in Section TV. 

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