In:
European Journal of Inorganic Chemistry, Wiley, Vol. 2018, No. 36 ( 2018-09-30), p. 4031-4043
Abstract:
We present herein the utilization of NHC‐stabilized alane adducts of the type (NHC) · AlH 3 [NHC = Me 2 Im ( 1 ), Me 2 Im Me ( 2 ), i Pr 2 Im ( 3 ), i Pr 2 Im Me ( 4 ), Dipp 2 Im ( 5 )] and (NHC) · Al i Bu 2 H [NHC = i Pr 2 Im ( 6 ), Dipp 2 Im ( 7 )] as novel hydride transfer reagents in the hydrodefluorination (HDF) of different fluoroaromatics and hexafluoropropene. Depending on the alane adduct used, HDF of pentafluoropyridine to 2,3,5,6‐tetrafluoropyridine in yields of 15–99 % was observed. The adducts 1 , 2 , and 5 achieved a quantitative conversion into 2,3,5,6‐tetrafluoropyridine at room temperature immediately after mixing the reactants. Studies on the HDF of fluorobenzenes with the (NHC) · AlH 3 adducts 1 , 3 , and 5 and (Dipp 2 Im) · Al i Bu 2 H ( 7 ) showed the decisive influence of the reaction temperature on the H/F exchange and that 135 °C in xylene afforded the best product distribution. Although the HDF of hexafluorobenzene yielded 1,2,4,5‐tetrafluorobenzene in moderate yields with traces of 1,2,3,4‐tetrafluorobenzene and 1,2,4‐trifluorobenzene, pentafluorobenzene was converted quantitatively into 1,2,4,5‐tetrafluorobenzene, with (Dipp 2 Im) · Al i Bu 2 H ( 7 ) showing the highest activity and reaching complete conversion after 12 h at 135 °C in xylene. The HDF of hexafluoropropene with (Me 2 Im) · AlH 3 ( 1 ) occurred even at low temperatures and preferably at the CF 2 group with the formation of 1,2,3,3,3‐pentafluoropropene (with 0.4 equiv. of 1 ) or 2,3,3,3‐tetra‐fluoropropene (with 0.9 equiv. of 1 ) as the main product.
Type of Medium:
Online Resource
ISSN:
1434-1948
,
1099-0682
DOI:
10.1002/ejic.v2018.36
DOI:
10.1002/ejic.201800589
Language:
English
Publisher:
Wiley
Publication Date:
2018
detail.hit.zdb_id:
1475009-0
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