## Abstract The dipeptide alanylproline has been prepared with the proline residue both ^13^C (15%) and ^15^N (95%) enriched. ^15^N NMR spectra of alanylproline reveal signals for both possible conformations—__cis__ and __trans__—of the dipeptide backbone in solution. Different p__K__ values for bo
Chemical polarisation of 15N and 13C nuclei in diazo coupling reactions
✍ Scribed by E. Lippmaa; T. Pehk; T. Saluvere; M. Mägi
- Publisher
- John Wiley and Sons
- Year
- 1973
- Tongue
- English
- Weight
- 345 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Chemical polarisation of nitrogen and carbon nuclei in the decomposition and diazo coupling reactions of benzenediazonium fluoborate has been investigated. If homo‐ and heterolytic processes run in parallel in a multistage reaction sequence, then the nuclear polarisation created in a free‐radical reaction can be nearly quantitatively carried over to products of rapid ionic reactions such as azo dyes.
📜 SIMILAR VOLUMES
## Abstract Measurement of the ^13^C NMR spectra of the bridgehead nitro compounds __1a–5a__ has been performed. It is found that one‐bond ^13^C^15^N coupling is not necessarily a reflection of the degree of s character of the bridgehead carbon exocyclic bonding orbital. Although the magnitude of
## Abstract The ^13^C NMR spectra of singly ^15^N‐labelled __Z__/__E__ isomers of azo and diazo compounds were recorded. The ^1^__J__(^13^C^15^N) coupling constants are strongly dependent on the geometrical configuration of the azo group, the relative position of the lone pair of electrons at the n
## Abstract Chemical polarisation of ^31^P nuclei was discovered and quantitatively measured in the peroxide‐phosphite system. The qualitative interpretation of the net polarisation of ^31^P nuclei and of its sign in the products of the radical reactions in the presence of phosphites is given withi
## Abstract On protonation of 3,4‐dihydroisoquinoline‐^15^N ^1^__J__(^13^C—1, ^15^N) is increased by a factor of five and ^1^__J__(^13^C—3, ^15^N) changes its sign, while on protonation of 3,4‐dihydroisoquinoline‐^15^N‐oxide the coupling constants, including the relatively large ^1^__J__(^13^C—1, ^