1-phenyl-1-ethyl cation

LUMO of 1-phenyl-1-ethyl cation reveals where the cation is able to bond to water. 

Examine the structure of 1-phenyl-1-ethyl cation. Is it chiral Examine the LUMO. Would you expect the cation to give a racemic mixture of alcohols or the mixture that is actually obtained Explain. 

Next, examine the structure of 1-phenyl-1-ethyl cation-chloride anion, an ion pair that is initially generated. What evidence is there for cai bon-chlorine bond cleavage Examine the electrostatic potential map for the ion pair. Which face of the cation is more available for attack How could the other enantiomer form ... 

The effect of an w-silyl group on the positive charge in benzyl cations can be estimated by comparing the NMR spectroscopic data for the 1 -phenyl- 1-trunethylsilylethyl cation 290 with those for the phenyl ethyl cation 78 and the cumyl cation 292 prepared under identical conditions from the corresponding chlorides with Sbl 5. The 1II and 13C NMR data for 78, 290 and 292114 measured under comparable conditions are given in Tables 10 and 11. 

It has, in fact, been shown that the absorption bands do not originate from the 1-phenyl ethyl cation, but mainly from the l-(oligostyrene)-3-phenyl indane cation, and therefore from a termination reaction ... 

Fig. 8. Sensitizing dyes of the cyanine class. K. = N — alkyl or chalcogens (O, S, Se, Te) R = chloro, phenyl, or additional benzene ring R = methyl, ethyl, or hydrogen n = 0, 1, 2 and RPRIME, R " = alkyl or sulfoalkyl. Solubihty in methanol for a carbocyanine dye n = 1 X = S R = Cl R = ethyl. Cationic dye (R" = R " = ethyl anion = bromide) 9.5 mmol/T. neutral dye (R" = ethyl R " = sulfopropyl) 3.6 mmol/L anionic dye (R" = R = sulfopropyl ...

Electrostatic potential map for i-phenyl-l-ethyl cation-chloride anion shows negatively-charged regions (in red) and positi vely-charged regions (in blue). 

Early attempts to generate the 1-phenyl-l-(trimethyl ilyl)ethyl cation 1 by ionization of the 1-phenyl-l-(trimethylsilyl)ethanol 2 with FS03H in S02C1F at -78 °C were unsuccessful. Only the cumyl cation 3 was observed instead (77). 

When 1-phenyl-1-trimethylsilyl ethylchloride 4 is reacted with SbF5 under carefully controlled experimental conditions at -125 °C, the 1-phenyl-1-(trimethylsilyl)ethyl cation 1 is generated exclusively as iridicated by H and 13C (Figure 1) and 29Si NMR spectra (12, 13, 14)... 

Due to the benzylic p-Tc resonance stabilization the C+-C,pso bond has partial double bond character and the ortho, ortho and meta, meta methine groups syn and anti to the silyl group are non-equivalent. The effect pf the a-silyl group on the positive charge in benzyl cations can be estimated by comparison of the NMR spectroscopic data of the 1 -phenyl-1 -(trimethylsilyl)ethyl cation 1 with those for the 1-phenylethy 1 cation 5 (P) and the cumyl pation 3 (15, 16, 17) (Table 1). 

Figure 1 I3C NMR spectrum of 1 -phenyl-1 -(trimethylsilyl) ethyl cation 1 in S02CIF/S02F2 at -127 °C, reference capillary CD3COCl (12, 14)...

The l-phenyl-2-(triisopropylsilyl)ethyl cation 12 is formed by reaction of ( >l-phenyl-2-(triisopropylsilyl)-ethene 13 with SbF5/FS03H (1 4) at -135°C (13). 

The experimental H, 13C (Figure 2) and 29Si- (Figure 3) NMR spectra show the exclusive formation of l-phenyl-2-(triisopropylsilyl)ethyl cation 12 and give proof of its structure and conformation (75). 

Figure 2 13C NMR spectrum of l-phenyl-2-(triisopropylsUyl) ethyl cation 12 in SO2CIF/SO2F2 at -123 °C, peaks of reference capillary CD3COCl (13)...

The phenyl cation (134) firstpostulated by Waters335 is a highly reactive species oflow stability and plays a fundamental role in organic chemistry—for example, in the chemistry of diazonium ions. According to gas-phase studies and calculations, its stability is between that of the ethyl cation and the vinyl cation.336 Since it is an extremely electrophilic and short-lived species, it could not be isolated or observed directly in the condensed phase. For example, solvolytic and dediazoniation studies under superacidic conditions by Faali et al.337,338 failed to find evidence of the intermediacy of the phenyl cation. Hyperconjugative stabilization via orf/zo-Me3Si or... 

Figure 4 Geometry of l-phenyl-2-(trimethylsilyl)ethyl cation (14) (B3LYP/6-31G(d)) (20)...

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