CeZSM-5—a designer's catalyst for selective synthesis of octahydroacridine

Abstract

High activity of cyclohexanone, formaldehyde and ammonia to form 1,2,3,4,5,6,7,8-octahydroacridine (OHA) is observed over different classes of zeolites and molecular modeling studies confirm the suitability of HZSM-5 catalyst for selective synthesis of OHA.

Highly Selective Synthesis of Octahydroaminoacridine over Mesoporous ZnAlMCM-41 Catalysts

“…ZnMCM-41 (21) produces lower OA selectivity than other mesoporous catalysts but increases the selectivity of DCA as its acid sites increase to improve an amino-condensation between the two CHCOs with NH 3 , as revealed in the literature. 15,16 Based on the literature results, the results of FTIR-pyridine and ammonia-TPD indicate that the acid sites of all the microporous catalysts are almost similar as confirmed elsewhere. 21 Zeolite Hβ (20) with pore size of 7.6 and 5.4 Å has fewer acid sites than HY(2.6) because of a lower aluminum content and produces a 12.4% OA selectivity; this is much less active than HY(2.6) (pore size 7.4 Å), which has a 25.9% OA selectivity.…”

“…Mesoporous AlMCM-41 (15) produces OA, DCA, and OHA with selectivities of ∼44, ∼30, and ∼17%, respectively. 15,16 CoAlMCM-41 has higher OA selectivity (67%) than mesoporous aluminosilicates such as AlMCM-41 (15) and AlMCM-41(30) because of its higher acid strength, which can be more favored for cyclization and aromatization than AlMCM-41 (15). From these literature results, 15,16 catalyst system produces the direct condensation product, DCA, with 21% selectivity.…”

“…The OHA selectivity with a feed ratio of 2:1:3 is higher than other feed ratios because the ratio of the reactant may be correlated for the deamination of OA. 15,16 A DCA selectivity increases from 18 to 38% with feed ratios of 2:1:1 and 2:1:2. An investigation of the effect of different ratios clearly proves that a 2:1:5 feed ratio is ideal among all the ratios applied for the highly selective synthesis of OA.…”

“…As showed in literature, 15,16 the mesoporous aluminosilicate catalysts, AlMCM-41 (15) and AlMCM-41(30), were prepared using corresponding n Si /n Al ratios of ∼15 and 30 in the product, with a basic hydrothermal method, and were used as the catalysts in the vapor phase cyclization of CHCO with a mixture of HCONH 2 and NH 3 . Mesoporous AlMCM-41 (15) produces OA, DCA, and OHA with selectivities of ∼44, ∼30, and ∼17%, respectively.…”

“…The zeolites and mesoporous catalysts were used as heterogeneous catalysts for the synthesis of OA and OHA as reported elsewhere. 15,16 To the best of our knowledge, the synthesis of OA by using ZnAlMCM-41 catalysts, which were synthesized by the Selvaraj research group, 17,18 has not been clearly reported until now. This study introduces a facile method for the selective synthesis of OA using cheap raw chemicals, such as CHCO, HCONH 2 and NH 3 , under a single-step vapor phase method.…”