17,166 research outputs found
The engagement of the Confederate fleet under Sir George Rook ... on the thirteenth of Aug. 1704 off of Malaga
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 46 c
The burning of ye Spanish galleons and flota and ye French men of war under monsr Chateau Renard at Vigo ... on the twelfth of October, 1702
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 49 c
Barcelona taken by the Confederate fleet & army october 20, 1705 ...
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 44 cm, full 35 x 46 c
The engagement of the Confederate fleet under Sir George Rook ... on the thirteenth of Aug. 1704 off of Malaga
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 46 c
The burning of ye Spanish galleons and flota and ye French men of war under monsr Chateau Renard at Vigo ... on the twelfth of October, 1702
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 49 c
The raising ye siege of Gibraltar, & destroying monsr. Ponti's squadron by sir John Leake, March 20, 1704/5
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 47 c
The raising ye siege of Gibraltar, & destroying monsr. Ponti's squadron by sir John Leake, March 20, 1704/5
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 45 cm, full 35 x 47 c
Barcelona taken by the Confederate fleet & army october 20, 1705 ...
No full text1 vista, col. – Pertany a l'obra "England's glory" de William Rayner (Londres, 1738)31 x 44 cm, full 35 x 46 c
Guanidine-Catalyzed Reductive Amination of Carbon Dioxide with Silanes: Switching between Pathways and Suppressing Catalyst Deactivation
No full textA mechanistic investigation into the guanidine-catalyzed reductive amination of CO₂, using a combination of ¹H, ²⁹Si NMR, FT-IR, MS, and GC profiling, is reported. Inexpensive and readily available N,N,N′,N′-tetramethylguanidine (TMG) was found to be an equally effective catalyst compared to more elaborate cyclic guanidines. Different catalytic pathways to formamide 2, aminal 4, and N-methylamine 3 were identified. A pathway to formamide product 2 dominates at 23 °C. Increasing the reaction temperature to 60 °C enables a competitive, higher-energy pathway to 4 and 3, which requires direct reduction of CO₂ with PhSiH₃ to formoxysilane E. Reduction of aminal 4, in the presence of CO₂ and the catalyst, led to formation of a 1:1 ratio of 2 and 3. The catalyst itself can be formylated under the reaction conditions, resulting in its deactivation. Thus, alkylated TMGs were found to be more stable and more active catalysts than TMG, leading to a successful organocatalyzed reductive functionalization of CO₂ with silane at 0.1 mol % catalyst loading (TON = 805 and TOF = 33.5 h‾¹)
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