No-Deuterium Proton (No-D) NMR as a Convenient Method for Analysis of Organic Solvents.

NMR spectra of 25 neat solvents have been recorded using No-D (no-deuterium proton) NMR, and water signals are visible in all spectra. Larger amounts of water can be measured by integration. Water can easily be detected at 0.

3-Substituted-1-(Trimethylsilylmethyl)cyclobutyl Cations: Stereochemistry of Solvent Capture of β-Trimethylsilyl Carbocations.

3--Butyl- or phenyl-substituted-1-(trimethylsilylmethyl)cyclobutyl trifluoroacetates react in methanol via β-trimethylsilyl carbocationic intermediates formed from loss of trifluoroacetate ion. These cationic intermediates react to give a significant amount of methyl ether substitution products along with the expected alkene elimination products. Different methyl ether substitution products are formed from isomeric trifluoroacetates, and complete retention of configuration of the ether group relative to the starting trifluoroacetates is observed.

The Nature of Azo-Substituted Carbocations: N-N π-Electron Stabilization versus Nitrogen Nonbonding Electron Stabilization.

Computational and experimental studies reveal two different modes of cation stabilization by the phenylazo group. The first mode involves a relatively weak conjugative interaction with the azo π-bond, while the second mode involves an interaction with the nitrogen nonbonding electrons. The 4-phenylazo group is slightly rate-retarding in the solvolysis of cumyl chloride and benzyl mesylate derivatives but rate-enhancing in the solvolysis of α-CF benzylic analogs.

3--Butyl-1-methylcyclobutyl Cation. Experimental vs Computational Insights into Tertiary Bicyclobutonium Cations.

The stereochemistry of the substitution product formed when (1,3)-3-(-butyl)-1-methylcyclobutyl methanesulfonate, , reacts in trifluoroethanol is one of retention of configuration. This is consistent with the intermediacy of a nonclassical bicyclobutonium cation . As the solvent becomes less highly ionizing, the product contains increasing amounts of the isomeric inverted product.

The cyclopropylcarbinyl route to γ-silyl carbocations.

The mesylate derivative of -1-hydroxymethyl-2-trimethylsilylcyclopropane has been prepared, along with a number of related mesylates and triflates with substituents on the 1-position. These substrates all solvolyze in CDCOD to give products derived from cyclopropylcarbinyl cations that undergo further rearrangement to give 3-trimethylsilylcyclobutyl cations. These 3-trimethylsilylcyclobutyl cations are stabilized by a long-range rear lobe interaction with the γ-trimethylsilyl group.