- Optimization of adiponitrile hydrolysis in subcritical water using an orthogonal array design
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A study of the hydrolysis of adiponitrile (ADN) was performed in subcritical water to research the dependence on experimental conditions. An L25(56) orthogonal array design (OAD) with six factors at five levels using statistical analysis was employed to optimize the experimental conditions for each product in which the interactions between the variables were temporarily neglected. The six factors were adiponitrile concentration (ADN c, wt%), temperature (T), time (t h), percentage of additives (reactant/additive, wt/wt%), additives (A), and pressure (p, MPa). The effects of these parameters were investigated using the analysis of variance (ANOVA) to determine the relationship between experimental conditions and yield levels of different products. The results showed that (ADN c) and T had a significant influence on the yields of adipamide, adipamic acid, and adipic acid at p0.05. Time was the statistically significant factor for the yield of 5-cyanovalermic acid at p0.05 and (ADN c) was the significant factor for the yield of 5-cyanovaleramide at p0.1. Finally, five supplementary experiments were conducted under optimized conditions predicted by the Taguchi method; the results showed that the yield obtained of each product was no lower than that of the highest in the 25 experiments. Carbon balance was calculated to demonstrate the validity of the experimental technique and the reliability of the results. Based on the experimental results, a possible reaction mechanism was proposed.
- Duan, Peigao,Wang, Yuanyuan,Yang, Yan,Dai, Liyi
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p. 241 - 258
(2009/10/17)
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- Exploring the synthetic applicability of a cyanobacterium nitrilase as catalyst for nitrile hydrolysis
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The substrate specificity and synthetic applicability of the nitrilase from cyanobacterium Synechocystis sp. strain PCC 6803 have been examined. This nitrilase catalyzed the hydrolysis of both aromatic and aliphatic nitriles to the corresponding acids in high yields. Furthermore, the stereoselective hydrolysis of phenyl-substituted β-hydroxy nitriles to (S)-enriched β-hydroxy carboxylic acids and selective hydrolysis of α,ω- dinitriles with five or less methylene groups to ω-cyano carboxylic acids have been achieved. This suggested that nitrilase from Synechocystis sp. PCC 6803 could be a useful enzyme catalyst for the "green" nitrile hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Hua, Ling
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p. 5238 - 5242
(2007/10/03)
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- Reaction of 3,5-disubstituted 4,5-dihydroisoxazoles with hexacarbonylmolybdenum
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Depending on the reaction conditions and structure of the 5-substituent, reactions of substituted 4,5-dihydroisoxazoles with hexacarbonylmolybdenum involve cleavage of the heteroring at the N-O bond, its aromatization, or/and 1,3-decyclization.
- Koroleva,Katok,Lakhvich
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p. 1003 - 1008
(2007/10/03)
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- Rationalisation of the regioselective hydrolysis of aliphatic dinitriles with Rhodococcus rhodochrous AJ270
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Aliphatic dinitriles undergo regioselective hydrolysis with the title organism to give monoacids with up to four methylenes between the nitrile functions (optimally 2-3) or when either an oxygen is placed β, γ or δ to the nitrile (δ-placement being optimal) or β or γ (optimally γ) but not δ sulfur substituents are present; nitrogen substituents appear to behave as for oxygen but suffer a steric limitation of the size of the nitrogen substituent.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1041 - 1042
(2007/10/03)
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- Regioselective biotransformations of dinitriles using Rhodococcus sp. AJ270
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A variety of dinitriles have been hydrolysed selectively under very mild conditions using Rhodococcus sp. AJ270. Aliphatic dinitriles NC[CH2]nCN 1 undergo regioselective hydrolysis to give the mono acids 2 with up to 4 methylenes between the nitrile functions while those with n > 4 give the diacids 3 in good yield. Dinitriles NC[CH2]nX[CH2]nCN 4 bearing an ether or sulfide linkage are efficiently transformed into the mono acids 5 when an oxygen is placed β, γ or δ to the cyano group or a β- or γ-sulfur is present. Hydrolysis of N,N-bis(2-cyanoethyl)anilines 4h-j takes place slowly affording exclusively the monoacids 5h-j while the monocyano amides 5o-p are obtained as the sole isolable product from rapid hydrolysis of the corresponding N,N-bis(2-cyanomethyl)butylamine 4o and N,N-bis(3-cyanopropyl)butylamine 4p. Higher homologues of arylimino- and butylimino-dinitriles are inert to enzymatic hydrolysis. A variety of other aliphatic dinitriles have been converted readily into mono acids in good to excellent yields except for o-phenylenediacetonitrile which gives o-phenylenediacetamide as the major product. The title organism also effects the hydrolysis of aromatic dinitriles with regiocontrol such as m- and p-dicyanobenzenes, but nct the ortho-substituted analogue. The scope and limitations of this enzymatic process have been systematically studied and the mechanism of regioselective hydrolysis has been discussed in terms of a chelation-deactivation effect.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 3197 - 3204
(2007/10/03)
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