PROCESS FOR PHOTOCATALYTIC ACCEPTOR-FREE DEHYDROGENATION OF ALKANES AND ALCOHOLS
A process for photocatalytic acceptor-free dehydrogenation of alkanes and alcohols, in which an alkane or an alcohol is irradiated in the presence of a rhodium complex containing organic phosphorus(III) compounds as ligands as a catalyst, and in the presence of at least one Lewis base is provided.
1 . A process for dehydrogenation of an alkane or an alcohol, comprising:
irradiating the alkane or alcohol in a reaction mixture comprising a rhodium complex and a Lewis base to remove hydrogen from the alkane or alcohol;
wherein
a hydrogen acceptor is not present, and
the rhodium complex comprises a ligand of an organic phosphorus(III) compound.
2 . The process according to claim 1 ,
wherein the Lewis base is an organic amine.
3 . The process according to claim 1 ,
wherein the Lewis base is a heterocyclic amine.
4 . The process according to claim 1 ,
wherein the Lewis base is at least one selected from the group consisting of a bipyridine, bathocuproin and phenanthroline.
5 . The process according to claim 4 ,
wherein the Lewis base is a bipyridine and is 2,2-bipyridine and/or 4,4-bipyridine.
6 . The process according to claim 1 ,
wherein the Lewis base used is bathocuproin or phenanthroline.
7 . The process according to claim 1 ,
wherein the reaction is conducted in the presence of CO 2 .
8 . The process according to claim 1 ,
wherein the irradiation is conducted with light of wavelength 320 nm to 500 nm.
9 . The process according to claim 1 ,
wherein a temperature of the dehydrogenation is from 45° C. to 120° C.
10 . The process according to claim 1 ,
wherein the rhodium complex is of formula (I):
Rh(L 1 ) 2 (CO)X (I)
wherein
L 1 is P(C 1 -C 5 alkyl) 3 , and
X is chloride, bromide or acetate.
11 . The process according to claim 10 , wherein
L 1 is PMe 3 or PtBu 3 .
12 . The process according to claim 10 , wherein X is chloride.
13 . The process according to claim 1 , wherein the rhodium complex is of formula (II):
Rh 2 (L 2 ) 2 (CO) 2 (X) 2 (II)
wherein
L 2 is P(Ph) 2 (CH 2 ) n P(Ph) 2 ,
n is from 1 to 3, and
X is chloride, bromide or acetate.
14 . The process according to claim 13 , wherein
L 2 is P(Ph) 2 (CH 2 ) P(Ph) 2 .
15 . The process according to claim 13 , wherein X is chloride.
16 . The process according to claim 1 , wherein
a carbon chain length of the alkane or the alcohol is from 2 to 30 carbon atoms.
17 . The process according to claim 1 , further comprising removing the hydrogen from the reaction mixture.
18 . The process according to claim 1 , wherein the dehydrogenation is conducted in a glass reactor or a metal reactor comprising glass.
19 . The process according to claim 1 , wherein the dehydrogenation is conducted in a single-wall glass reactor having a wall thickness of from 1.0 to 3.0 mm.
20 . The process according to claim 1 , wherein a turnover number is greater than 1000.