Effect of the synthetic method of Pt/MgO in the hydrosilylation of phenylacetylene

Abstract

This work describes the synthesis and characterization of Pt/MgO (Pt/Mg(OH) 2 , calcined Pt/MgO and agglomerated Pt/MgO ) catalysts. The supports of the catalysts were obtained by the hydrolysis-precipitation method and the metallic phase of platinum was incorporated by impregnation. The characterization of the synthesized materials was made by means of DRX, FTIR, TGA-DTA and TPR techniques. The catalysts were applied to the hydrosilylation of PhC≡CH with three different silanes (Ph 3 SiH, Ph 2 MeSiH and PhMe 2 SiH) as a model reaction. The activity of the proposed catalysts Pt/Mg(OH) 2 , calcined Pt/MgO and agglomerated Pt/MgO had a reaction yield of 95 %. When the catalysts Pt/Mg(OH) 2 and agglomerated Pt/MgO were used in the reaction with Ph 3 SiH, the selectivity to the trans isomer was favored (90%). A relationship was found between the increase in the reaction time and the increase of the kinetic volume of the silane radicals. The present results were compared to the previously obtained results using as a catalyst Pt/MgO obtained by the sol-gel method.

Cobalt-Catalyzed Dehydrogenative Silylation of Vinylarenes

“…1 H NMR (CDCl 3 , 400 MHz) δ: 7.65～7.58 (m,4H),7.48～7.35 (m,8H),7.07～6.98 (m,3H),6.62 (dd,J＝3.2,18.8 Hz,1H), 5.23 (d, J＝3.2 Hz, 1H); 13 C NMR (CDCl 3 , 100 MHz) δ: 162.9 (d,J＝247.1 Hz,1C),147.7,135.5,134.1,133.4,129.8,128.3 (d,J＝ 8.1 Hz,1C),128.1,121.2,115.5 (d,J＝21.2 Hz,1C); 19 F NMR (376.5 MHz, CDCl 3 ) δ: -112.9; IR (neat) ν: 3068,3016,2124,1602,1506 (m, 1H), 6.79 (dd, J＝3.2, 19.2 Hz, 1H), 5.25 (d, J＝3.2 Hz, 1H); 13 C NMR (CDCl 3 , 100 MHz) δ: 160.3 (d, J＝ 249.4, 1C), 140.9, 135.5, 133.3, 129.8, 128.1, 127.2, 125.7 (d, J＝11.7, 1C), 124.8, 124.0, 115.7 (d, J＝21.9, 1C); 19 F NMR (376.5 (E)-(2-(Naphthalen-1-yl)vinyl)diphenylsilane (3m): Colorless oil (0.2554 g, 76% yield). 1 H NMR (CDCl 3 , 400 MHz) δ: 8.09～8.02 (m, 1H), 7.94～7.72 (m, 4H), 7.72～ 7.65 (m, 4H), 7.53～7.37 (m, 9H), 6.81 (dd, J＝4.0, 18.8 Hz, 1H), 5.34 (d, 1H); 13 C NMR (CDCl 3 , 100 MHz) δ: 146.5, 135.9, 135.5, 135.1, 133.6, 130.9, 129.8, 128.7, 128.5, 128.1, 126.2, 125.8, 125.6, 125.5, 123.9, 123.4;IR (neat) ν: 3064, 3013, 2856IR (neat) ν: 3064, 3013, , 2122IR (neat) ν: 3064, 3013, , 1594 (E)-Methyldiphenyl(styryl)silane (3n): [30] Colorless...…”

“…(E)-Dimethyl(phenyl)(styryl)silane (3o): [30] Colorless oil (0.1054 g, 88% yield). 1 H NMR (CDCl 3 , 400 MHz) δ: 7.61～7.53 (m, 2H), 7.47～7.41 (m, 2H), 7.40～7.29 (m, 5H), 7.28～7.22 (m, 1H), 6.94 (d,J＝19.2 Hz,1H), 6.58 (d,J＝19.2 Hz,1H),0.43 (s,6H).…”

Impregnated Platinum on Magnetite as an Efficient, Fast, and Recyclable Catalyst for the Hydrosilylation of Alkynes

“…No better results have been achieved using platinum catalyst immobilized on carbon, , magnesium oxide, γ-alumina, silica, − and titania . Even, the platinum(IV) oxide has been used as heterogeneous catalyst .…”

“…To avoid the aforementioned drawbacks, platinum species have been immobilized on different organic polymers, 50−52 obtaining a modest regioselectivity (about 3.5:1 isomeric ratio) with platinum loadings and reaction times from 1 to 5 mol % in from 1 to 24 h. The only catalyst which could be recovered and reused was an incarcerated platinum polymer. 51 No better results have been achieved using platinum catalyst immobilized on carbon, 53,54 magnesium oxide, 55 γ-alumina, 56 silica, 57−60 and titania. 61 Even, the platinum(IV) oxide has been used as heterogeneous catalyst.…”