Metal-free photocatalytic hydrosilylation of olefins in the presence of photoinitiators

Abstract

A convenient metal-free photocatalytic hydrosilylation of variety of linear and cyclic alkenes have been investigated. It was found that the free radical type photoinitiator Irgacure 2959 had a better effect...

Photocatalyzed Hydrosilylation in Silicone Chemistry

“…Besides, more active and more controlled catalytic systems could open up new possibilities for higher resolutions and faster 3D printing. Already described photosensitive catalysts of silicone hydrosilylation always contain expensive Pt, but there are recent examples in the open literature of metal-free photohydrosilylation catalysts , that could potentially be exploited for silicone curing.…”

“…These values were between 20 and 40 sec for inhibitor-free systems and almost did not change with the addition of the inhibitor. The same company also patented some hydrosilylation formulations containing triphenylphosphine (112) or tris(2,4-di-tert-butylphenyl)phosphite (113) as inhibitors to increase the shelf life of the mixtures 84 .…”

“…These values were between 20 and 40 s for inhibitor-free systems and almost did not change with the addition of the inhibitor. The same company also patented some hydrosilylation formulations containing triphenylphosphine (112) or tris(2,4-di-tert-butylphenyl)phosphite (113) as inhibitors to increase the shelf life of the mixtures. 84 An SiHand vinyl-containing silicone mixture (SEMICOSIL 912 by Wacker Chemie AG) was mixed with (methyl-Cp)trimethylplatinum (63) (30 ppm of Pt content), and the evolution of viscosity was studied with and without inhibitors (Figure 26).…”

“…Interestingly, benzophenone (40, Figure 6) was tested as a potential photosensitizer, but it only slowed down the curing and slightly increased the shelf life of the formulation. The increase of Pt concentration to 135 ppm did not accelerate the curing, but reduced the shelf life to 2.5 h. Several experiments were performed at a lower Pt concentration (around 18 ppm); higher dose of UV light was required for curing (7.2 J/cm 2 ), but even at a much lower DEADC concentration (around 450 ppm), the shelf life was >30 h. Note that several other compounds happened to be unsuitable as photosensitive inhibitor: pyrazole (115) (900 ppm) and butylallylmaleate (116) (1800 ppm) completely prevented the curing even after an elevated dose of UV exposure (8−10 J/cm 2 ), while a z o b e n z e n e ( 1 1 7 ) ( 1 8 0 0 p p m ) , 1 , 1 ′ -a z o b i s -(cyanocyclohexane) (118 (900 ppm), and 2,2′-azobis(2- 63) and triphenylphosphine (112) or tris(2,4-di-tert-butylphenyl)phosphite (113). 84 Industrial & Engineering Chemistry Research 86 Silicone formulations containing Karstedt's catalyst (60 ppm Pt content) and from 800 to 3000 ppm of DEADC were subjected to thermal curing (100 °C) with or without preliminary UV treatment (0.2 s, Philips type HOK6 UV lamp, linear density 8 kW/m).…”

N,N‐Dimethylformamide‐protected Fe2O3 Combined with Pt Nanoparticles: Characterization and Catalysis in Alkene Hydrosilylation

“…3 u [22d] dodecyldiphenylsilane, 54 %, a colorless oil, 1 H‐NMR (400 MHz CDCl 3 ) δ: 7.56 (4H, dd, J =7.3, 1.5 Hz), 7.40–7.34 (6H, m), 4.85 (1H, t, J =3.7 Hz), 1.48–1.12 (22H, m), 0.89 (3H, t, J =6.9 Hz); 13 C‐NMR (100 MHz CDCl 3 ) δ: 135.12 (CH), 134.71 (C), 129.44 (CH), 127.92 (CH), 33.17 (CH 2 ), 31.92 (CH 2 ), 29.65 (CH 2 ), 29.53 (CH 2 ), 29.35 (CH 2 ), 29.21 (CH 2 ), 24.38 (CH 2 ), 22.69 (CH 2 ), 14.12 (CH 3 ), 12.12 (CH 2 ). GC‐MS (EI) m/z (relative intensity) 274 (7) [M−C 6 H 6 ] + , 196 (20), 183 (100), 175 (30), 105 (23).…”