Catalysis of Zeolite in the Amidation of Alcohols with Nitriles for the Synthesis of N-Alkylacrylamides

Abstract

The catalytic applicability of zeolites in the Ritter reaction of acrylnitrile (AN) with various alcohols for the synthesis of N-alkylacrylamide was studied. In terms of the maximum amide selectivity, the optimum zeolite structure was FAU for the reaction of AN with tertiary alcohol and MFI for that with secondary alcohols. A reaction scheme involving nucleophilic substitution of carbocation intermediates is proposed. It was suggested that the Ritter reaction is acidity demanding, hydrophobicity favorable and pore size sensitive. Accordingly, amide product selectivity and yield can be improved by using zeolites with strong acidity, or with mesopores generated by base treatment, enhancing hydrophobicity by tuning appropriate silica/alumina ratio or by silica vapor deposition. Base post treatment can promote amide product selectivity effectively.

Organic template-free synthesis of zeolite Y nanoparticle assemblies and their application in the catalysis of the Ritter reaction

“…Similar phenomenon was also reported by Wu. 32 He reported that microporous zeolite HY with a lower external surface area inhibited the diffusion of the reactants, resulting in an unsatisfactory catalytic activity and selectivity in the Ritter reaction of acrylonitrile with t-butanol, compared to that of ultrastable mesoporous zeolite. Compared with Y-NA, although ZSM-5-M has a high mesoporous surface area (168 m 2 g À1 ) and mesopore volume (0.37 cm 3 g À1 ), the p-tolunitrile conversion over HZSM-5-M is only 59% ( Table 2).…”

“…Wu also reported that because of the steric hindrance effect due to the micropore size (0.55 nm) in mesoporous zeolite ZSM-5, tbutanol is not easily accessible to the acidic sites in the microporous channels, resulting in lower target product selectivity over mesoporous zeolite ZSM-5 in the Ritter reaction of acrylonitrile with t-butanol. 32 The possible reaction mechanism over HY-NA is shown in Fig. 7.…”

“…This carbocation is attacked by electron-rich p-tolunitrile nucleophiles to form the nitrilium ion 6, 32 which is subsequently attacked by a water molecule, followed by the elimination of a proton to generate the nal compound. 32…”

Acidic Ionic Liquid Bridge Supported on Nano Rice Husk Ash: An Efficient Promoter for the Conversion of Nitriles to Their Corresponding 5‐Substituted 1H‐Tetrazoles and Amides

“…A variety of catalysts have been used to facilitate the Ritter reaction such as 2,4-dinitrobenzenesulfonic acid (DNBSA), [37] Zn(ClO 4 ) 2 ⋅ 6H 2 O, [38] propylphosphonic anhydride (T3P), [39] Bismuth salts, [40] Sulfated polyborate, [41] Sulfated tungstate, [42] FeCl 2 ⋅ 4H 2 O, [43] I 2, [44] FeCl 3 [45] and Zeolite. [46] Despite the improved results, each of the methods used for the above mentioned compounds suffer from disadvantages including long reaction times, harsh reaction conditions, need for excess amounts of reagents, use of organic solvents, use of toxic reagents, and non-recoverability of the catalyst. Due to these restrictions, introduction of simple and effective methods and catalysts for the synthesis of these compounds is still under investigation.…”

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

“…4 Till date, various alternative methodologies have been reported to achieve chemo-selectivity with higher yields under milder conditions to improve 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.…”