I. Electrophilic reactions of p-toluenesulfonyl azide. II. 15N and 13C nuclear magnetic studies of aryldiazonium compounds effect of substituent, solvent and 18-crown-6

Citation

Casewit, Carla Jutta (1981) I. Electrophilic reactions of p-toluenesulfonyl azide. II. 15N and 13C nuclear magnetic studies of aryldiazonium compounds effect of substituent, solvent and 18-crown-6. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-01112005-143434

Abstract

Part I. Electrophilic Reactions of p-Toluenesulfonyl Azide.

Section 1. Review of Electrophilic Reactions of p-Toluenesulfonyl Azide.

The electrophilic reactions of p-toluenesulfonyl azide are reviewed using the principles of hard and soft acids and bases (HSAB).

Section 2. The Reaction of p-Toluenesulfonyl Azide with the Sodium Salt of p-Toluenesulfonamide.

A number of concurrent reactions of p-toluenesulfonyl azide-2-15N (I-3-15N) with the sodium salt of p-toluenesulfonamide were followed by 15N NMR. I-2-15N is formed as a result of a degenerate diazo transfer by I-3-15N to p-toluenesulfonamide anion. p-Toluenesulfonamide anion also reacts with 1-3-15N to give di-p-toluenesulfonamide and azide ion. The 15-N-labeled azide ion exchanges with I to give I-1-15N. I also reacts with azide ion, yielding dinitrogen and p-toluenesulfinate anion. The sulfinate salt reacts readily and reversibly with I to give 1,3-di-p-toluenesulfontriazene anion, which provides another pathway for interconversion of 1-3-15N and I-1-15N.

Section 3. The Reaction of p-Toluenesulfonyl Azide with Potassium Azide.

The reaction of p-toluenesulfonyl azide with potassium azide-I-15N has been examined in toluene and dichloromethane by 15N NMR. In addition to azide-ion exchange leading to 1-1-15N and I-3-15N, the formation of 1-2-15N is indicated. Two mechanisms for this novel scrambling are proposed. Azide-ion metathesis involving reversible formation of an N-Pentazole derivative from I and azide ion, followed by azide exchange could account for the formation of 1-2-15N. Alternatively, a scrambling route involving the reversible addition of p-toluenesulfonylnitrene to 1-3-15N can be envisioned. The inhibition of scrambling in dichloromethane by addition of iodide ion suggests that a discrete p-toluenesulfonyl azide – azide ion intermediate is involved in any case.

Part II. 15N and 13C Nuclear Magnetic Resonance Studies of Aryldiazonium Compounds. Effect of Substituent, Solvent and 18-Crown-6.

15N and 13C shifts induced by addition of one equivalent of 18-crown-6 have been determined for several para-substituted aryldiazonium fluoborates in dimethylformamide. The [alpha]-nitrogen (N1) and para carbon (C4) shift upfield and the [beta]-nitrogen (N2) and C1 shift downfield on complexation. The effect of solvent on the positions of the 15N and 13C resonances of p-(n-butyl)benzenediazonium fluoborate are small. The influence of substituents on the 15N chemical shifts is relatively large and comparable to the effect of 18-crown-6. These 13C and 15N results, in conjunction with previous spectroscopic studies indicate that the crown ether complexed aryldiazonium cation is electronically more diazonium-like and less diazo-like than the uncomplexed form.

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