TY - JOUR

T1 - Catalytic hydrogenation with parahydrogen

T2 - A bridge from homogeneous to heterogeneous catalysis

AU - Kovtunov, Kirill V.

AU - Salnikov, Oleg G.

AU - Skovpin, Ivan V.

AU - Chukanov, Nikita V.

AU - Burueva, Dudari B.

AU - Koptyug, Igor V.

PY - 2020/7/1

Y1 - 2020/7/1

N2 - One of the essential themes in modern catalysis is that of bridging the gap between its homogeneous and heterogeneous counterparts to combine their individual advantages and overcome shortcomings. One more incentive can now be added to the list, namely the ability of transition metal complexes to provide strong nuclear magnetic resonance (NMR) signal enhancement upon their use in homogeneous hydrogenations of unsaturated compounds with parahydrogen in solution. The addition of both H atoms of a parahydrogen molecule to the same substrate, a prerequisite for such effects, is implemented naturally with metal complexes that operate via the formation of a dihydride intermediate, but not with most heterogeneous catalysts. Despite that, it has been demonstrated in recent years that various types of heterogeneous catalysts are able to perform the required pairwise H2 addition at least to some extent. This has opened a major gateway for developing highly sensitive and informative tools for mechanistic studies of heterogeneous hydrogenations and other processes involving H2. Besides, production of catalyst-free fluids with NMR signals enhanced by 3-4 orders of magnitude is essential for modern applications of magnetic resonance imaging (MRI), including biomedical research and practice. The ongoing efforts to design heterogeneous catalysts which can implement the homogeneous (pairwise) hydrogenation mechanism are reported.

AB - One of the essential themes in modern catalysis is that of bridging the gap between its homogeneous and heterogeneous counterparts to combine their individual advantages and overcome shortcomings. One more incentive can now be added to the list, namely the ability of transition metal complexes to provide strong nuclear magnetic resonance (NMR) signal enhancement upon their use in homogeneous hydrogenations of unsaturated compounds with parahydrogen in solution. The addition of both H atoms of a parahydrogen molecule to the same substrate, a prerequisite for such effects, is implemented naturally with metal complexes that operate via the formation of a dihydride intermediate, but not with most heterogeneous catalysts. Despite that, it has been demonstrated in recent years that various types of heterogeneous catalysts are able to perform the required pairwise H2 addition at least to some extent. This has opened a major gateway for developing highly sensitive and informative tools for mechanistic studies of heterogeneous hydrogenations and other processes involving H2. Besides, production of catalyst-free fluids with NMR signals enhanced by 3-4 orders of magnitude is essential for modern applications of magnetic resonance imaging (MRI), including biomedical research and practice. The ongoing efforts to design heterogeneous catalysts which can implement the homogeneous (pairwise) hydrogenation mechanism are reported.

KW - alkynes

KW - heterogeneous catalysis

KW - hydrogenation

KW - immobilization

KW - Mendeleev-21

KW - NMR

KW - reaction mechanisms

KW - ACTIVATION

KW - MRI

KW - CONVERSION

KW - COMPLEXES

KW - SOLID-STATE

KW - PAIRWISE

KW - INDUCED POLARIZATION

KW - GAS-PHASE HYDROGENATION

KW - PHIP

KW - LIVED SPIN STATES

UR - http://www.scopus.com/inward/record.url?scp=85091335864&partnerID=8YFLogxK

U2 - 10.1515/pac-2020-0203

DO - 10.1515/pac-2020-0203

M3 - Article

AN - SCOPUS:85091335864

VL - 92

SP - 1029

EP - 1046

JO - Pure and Applied Chemistry

JF - Pure and Applied Chemistry

SN - 0033-4545

IS - 7

ER -