Improved analysis of tritiated samples via a ³H‐NMR cryo‐probe

Abstract

Tritium ( 3 H) NMR spectra of a number of compounds prepared via metal-catalyzed H/T reduction/ exchange of unsaturated hydrocarbons are presented. These show the considerable benefits that emerge from using a tritium cryo-probe.

Rhodium‐ and ruthenium‐catalysed hydrogen isotope exchange

“…Whether this is an effect of the inevitably higher surface area or of increased surface dislocations could not be determined by the technique. The observation is consistent with the finding that supported dispersed rhodium is also active in such pyridine labelling 32, 35…”

“…Nevertheless Lockley et al . was impressed by the approach and resolved to improve the procedure 32. A range of platinum group metal catalysts were screened in parallel, utilizing deuterium gas at atmospheric pressure in a number of aprotic solvents 32.…”

“…was impressed by the approach and resolved to improve the procedure 32. A range of platinum group metal catalysts were screened in parallel, utilizing deuterium gas at atmospheric pressure in a number of aprotic solvents 32. Of these catalysts, rhodium black, ruthenium black and 5% rhodium on alumina proved many times more active than 5% Ru/C and hence showed potential for further development.…”

“…When 0.4 mol catalyst/mol of deuterium was utilized, 40% of the isotope was present in the olefin and 60% in the alkane. Both the cis and trans terminal positions of the styrene were labelled with equal efficiency 42. Such olefin labelling by employment of traditional hydrogenation catalysts and a limited amount of isotopic hydrogen has been utilized for the tritiation of dehydroleucine,43 cyclosporin44 FK506,45 and FK506 analogues 41.…”

30 Years with ortho‐directed hydrogen isotope exchange labelling

“…I mention in particular Tracy Smith for her work on the a and blabelling of piperidines, piperazines and secondary amines 42 and Stathis Alexakis for his development of an efficient catalytic system for the a-labelling of pyridines and other N-heterocyclics 43 and his still ongoing work, on the 2 H and 3 H exchange labelling of terminal alkenes over palladium catalysts. 44 …”