The Modification and Use of Supported Platinum Catalysts for Asymmetric Hydrogenation Reactions

Organic chemistry, Inorganic chemistry, Molecular chemistry

Allan, Elaine

University:University of Glasgow

关键词: Organic chemistry, Inorganic chemistry, Molecular chemistry;   

Others  :  http://theses.gla.ac.uk/74939/1/11007860.pdf

来源: University of Glasgow

【 摘 要 】

This thesis describes a study of the adsorption of chiral substituted binaphthalene molecules (2,2'-dihydroxy-l,l'-binaphthalene, 2,2'-diamino-1,1'-binaphthalene, 2,2- dimethoxy-1,1 '-binaphthalene and 2,2',7,7'-tetrahydroxy-1,1 '-binaphthalene) on to supported Pt catalysts (1% w/w Pt/gamma-alumma, 1% w/w Ft/Grace silica CIO and 1% w/w Pt/Cab-O- Sil) with a view to establishing a system which could be capable of inducing asymmetric hydrogenation of prochiral starting materials. The 2,2'-dihydroxy-l,l'-binaphthalene modifier was found to adsorb irreversibly on to the 1% w/w Pt/?-alumma and 1% w/w Pt/Grace silica CIO catalysts, prior to the ageing of the 1% w/w Pt/Grace silica CIO catalyst. The 2,2'-dihy droxy-l,l'-binaphthalene modifier was also found to irreversibly adsorb on to the yalumina support, to a similar extent as that on to the 1% w/w Pt/gamma-alumina catalyst. The 2,2'-diamino-1,1'-binaphthalene modifier was adsorbed irreversibly on to the 1% w/w Pt/gamma-alumina, 1% w/w Pt/Grace silica CIO and 1% w/w Pt/Cab-O-Sil catalysts. In the case of the 1% w/w Pt/Cab-O-Sil catalyst, the 2,2'-diamino-l,l'-binaphthalene was found to undergo a chemical reaction which resulted in the formation of 2-hydroxy-2'-amino-1,1'-binaphthalene and 2,2'-dihydroxy-1,1'- binaphthalene. 2,2-Dimethoxy-1,1'-binaphthalene modifier was found not to adsorb on to the (1% w/w Pt/gamma-alumina, 1% w/w Pt/Grace silica CIO and 1% w/w Pt/Cab-O-Sil catalysts. The 2,2',7,7'-tetrahydroxy-1,1'-binaphthalene modifier was found to be adsorbed on to the 1% w/w Pt/y-alumina and 1% w/w Pt/Cab-O-Sil catalysts, with the gamma-alumina support adsorbing the 2,2',7,7'-tetrahydroxy-1,1'-binaphthalene to a similar extent as that on to the 1% w/w Pt/gamma-alumina catalyst. Evidence is presented for the adsorption of 2,2'- dihydroxy-1,1'-binaphthalene, 2,2'-diamino-1,1'-binaphthalene and 2,2',7,7'-tetrahydroxy- 1,1'-binaphthalene modifiers are in a near vertical mode via their substituent groups, via the dissociation of a hydrogen atom. The adsorption of R-(-)-l-(9-anthryl)-2,2,2-trifluoroethanol was studied with respect to the 1% w/w Pt/gamma-alumina and 1% w/w Pt/Cab-O-Sil catalysts as well as the respective supports. It was found that only the 1% w/w Pt/gamma-alumina catalyst adsorbed this modifier. The adsorption of (S,S)-di-(2-propyl)-6,12-dioxa-2,5,13,16-tetraoxo-3,15,19- triazabicyclo [15.3.1] heneicosa-1 (21),17,19-triene and (S,S)-di-(2-propyl)-6,13-dioxa- 2,5,14,17-tetraoxo-3,16,20-triazabicyclo [16.3.1] docosa-1 (22),18,20-triene macrocycles were also studied, with the result that both the macrocycles were adsorbed on to both the 1% w/w Pt/gamma-alumina and 1% w/w Pt/Cab-O-Sil catalysts as well as the yalumina support. The 1% w/w Pt/gamma-alumina and 1% w/w Pt/Cab-O-Sil catalysts were studied for their co-adsorption properties with respect to the 2,2'-dihydroxy-1,1 '-binaphthalene and 2,2'-diamino-l,l'-binaphthalene modifiers. In the case of the 1% w/w Pt/Cab-O-Sil catalyst, 2,2'-dihydroxy-l,r-binaphthalene and 2-hydroxy-2'-amino-1,1'-binaphthalene were formed as well as 2,2'-diamino-l,r-binaphthalene being adsorbed. The hydrogenation of methyl tiglate and tiglic acid over the various modified supported Pt catalysts resulted in the formation of the racemate (methyl-2-methyl butyrate and 2-methyl butyric acid, respectively). However, the hydrogenation of 3-coumaranone over diamine modified supported Pt catalysts resulted in the inducement of enantioselectivity, that is, R-(+)-2,2'-diamino-l,l'-binaphthalene modified supported Pt catalysts induced S-3-benzofuranol and S-(-)-2,2'-diamino-l,l'-binaphthalene modified supported Pt catalysts induced R-3-benzofuranol.