Silica sulfuric acid: a reusable solid catalyst for the synthesis of N-substituted amides via the Ritter reaction

Continuous Flow Synthesis of Substituted 3,4-Propylenedioxythiophene Derivatives

“…We selected silica sulfuric acid (SSA) as the heterogeneous catalyst for our present investigation based on our earlier work under batch conditions. The catalyst was prepared and characterized using the reported methods, and the acid values of the prepared SSA was determined . The best SSA catalyst we chose was the one with the acid value of 6.5 mEq/g of the catalyst (details are provided inthe Supporting Information).…”

Bimetallic CoMoO4@C nanorod catalyzes one‐pot synthesis of benzimidazoles from benzyl alcohol and o‐phenylendiamine without alkali

“…[ 42 ] By contrast, o ‐aminobenzonitrile was hardly reacting with benzyl alcohol under the same conditions; this might be due to the preferential oxidation of cyanide groups on o ‐aminobenzonitrile, which led to the decreased selectivity of the reaction. [ 43–45 ]…”

“…[42] By contrast, oaminobenzonitrile was hardly reacting with benzyl alcohol under the same conditions; this might be due to the preferential oxidation of cyanide groups on oaminobenzonitrile, which led to the decreased selectivity of the reaction. [43][44][45] Distinctly, catalyst recycling was an important indicator of whether it could be industrialized. In view of this, works had been done to explore the reuse performance of CoMoO 4 @C-500.…”

Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert-butyl/N-trityl protected amides via Ritter reaction

“…These include a variety of Lewis and Bronsted acid/reagents such as sulfuric acid, 5,6 Mg(HSO 4 ) 2 , 7 silica-supported Fe(ClO 4 ) 3, 8 trifluoromethane sulfonic acid, 9 trifluoromethane sulfonic anhydride, 10 zeolites, 11 (BF 3 •OEt 2 ), 12 MnO 2 •SiO 2 , 13 bismuth Triflate, 14 DNBSA, 15 Ca(HSO 4 ) 2 , 16 TiCl 4 , 17 P 2 O 5 •SiO 2 , 18 Fe 3+ -K10 Montmorillonite, 19 PMA•SiO 2 , 20 Nafion-H, 21 NaHSO 4 /SiO 2 , 22 and H 2 PW 12 O 40 . 23 In addition to this, various catalytic systems are also reported which include silica sulfuric acid, 24 silica supported sulfonic acid, 25 silica-bonded Npropyl sulphamic acid (SBNPSA), 26 silica boron-sulfuric acid nanoparticles (SBSANs), 27 HClO 4 -functionalized silica-coated magnetic nanoparticles, 28 sulfated tungstate, 29 * For correspondence alumina-methanesulfonic acid (AMA), 30 nanocat-Fe-OSO 3 H, 31 35 Al(HSO 4 ) 3 , 2 ionic liquids, 36 iodine, 37 and polyvinylpolypyrrolidone-supported boron trifluoride. 38 However, these reagents and catalytic systems suffer from one of the following limitations such as the use of expensive and toxic reagents/catalysts, limited availability of reagent, hygroscopicity as well as instability of the reagents, use of strong protic media, harsh reaction condition, long reaction time, low yield and tedious workup procedure.…”