Synthese und Reaktionen optisch aktiver Cyanhydrine

Effenberger, Franz

doi:10.1002/ange.19941061504

Cited by 117 publications

(21 citation statements)

References 120 publications

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“…Cyanohydrins are valuable intermediates for the synthesis of range of compounds viz., a-amino acids, a-hydroxy acids, b-amino alcohols, vicinal diols and a-hydroxy ketones [1][2][3][4][5] which are important building blocks for numerous pharmaceuticals, agrochemicals and insecticides [6][7][8][9][10][11][12][13]. Cyanohydrins are conventionally synthesized by the cyanation of carbonyl compounds using KCN, NaCN, trimethylsilyl cyanide (TMSCN) and HCN as sources of cyanide in the presence of various Lewis acid/base catalysts [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions

et al. 2010

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N,N-Dimethylpyridin-4-amine (DAMP) (10 mol%) was successfully employed as catalyst for cyanoethoxycarbonylation of aromatic and aliphatic aldehydes at room temperature under solvent free condition to give corresponding ethylcyanocarbonates in excellent isolated yield (up to 95%) in 15-90 min. Simple experimental conditions and product isolation procedure has made this protocol quite attractive for the synthesis of ethylcyanocarbonates in an environment-friendly manner.

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Section: Introductionmentioning

confidence: 99%

N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions

et al. 2010

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“…For their asymmetric synthesis from hydrogen cyanide and aldehydes or ketones, enzymatic methods employing hydroxynitrile lyases are widely used [1,2,3,4,5,6,7,8,9,10]. In order to develop industrial production methods for (R)-cyanohydrins, using R-hydroxynitrile lyase from almonds, the non-enzymatic formation of racemic cyanohydrin has to be suppressed.…”

Section: Introductionmentioning

confidence: 99%

Comparison of a batch, fed-batch and continuously operated stirred-tank reactor for the enzymatic synthesis of (R)-mandelonitrile by using a process model

Willeman

Straathof

Heijnen

2001

Bioprocess Biosyst Eng

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The suitability of a batch, fed-batch and continuously operated stirred-tank reactor for the enzymatic production of (R)-mandelonitrile in an aqueous-organic biphasic system was investigated by using a process model. The considered biphasic system is 10±50% (v/v) 100 mM sodium citrate buffer of pH 5.5 dispersed in methyl tert-butyl ether. The constraints were that 750 moles of benzaldehyde per cubic meter should react towards (R)-mandelonitrile with an enantiomeric excess of 99% and a conversion of 98%. A continuously operated stirred-tank reactor could not meet the constraints, but the production in a batch or fed-batch reactor was feasible. The choice for a batch or fed-batch reactor is dependent on the in¯uence of the costs for reactor operation and for the enzyme on the product costs. The choice for operating at a small or large aqueous-phase volume fraction is dependent on the costs and reusability of the enzyme. The volumetric productivity is maximal when operating as batch. The enzymatic productivity and turnover are maximal when operating as fed batch. In the fed-batch mode, the enzymatic productivity increased by 24±37%, the turnover increased by 50±60% and the volumetric productivity decreased by 33±71% as compared to a batch reactor. By enhancement of mass transfer both the volumetric and enzymatic productivity can be increased considerably, while the turnover is only slightly decreased. List of symbolsC aq,j concentration in aqueous phase [mol.m aq ±3 ] C aq,E enzyme concentration [g.m aq ±3 ] C org,j concentration in organic phase [mol.m org ±3 ] C in org;j concentration in entering organic¯ow [mol.m org ±3 ] ee enantiomeric excess of (R)-mandelonitrile [%] F cont org;j¯o w rate continuous reactor [m org 3 .s ±1 ] k f cat forward catalytic constant [s ±1 ] k r cat reverse catalytic constant [s ±1 ] k non-enz forward chemical reaction rate constant [m aq 3 .mol ±1 .s ±1 ] k L,j a lumped mass transfer coef®cient [s ±1 ] K R eq ; K S eq enantiomeric equilibrium constant [m aq 3 .mol ±1 ] K RS eq racemic equilibrium constant [m aq 3 .mol ±1 ] K mj Michaelis constant for compound j [mol.m aq ±3 ] K ij inhibition constant for compound j [mol.m aq ±3 ] m j partition coef®cient [m aq 3 .m org ±3 ] n j total amount of compound j [mol] n 0 j initial total amount of compound j [mol] N fb j feed rate of compound j [mol.s ±1 ] r j reaction rate for compound j [mol.m aq ±3 .s ±1 ] t time [s] t conv time to obtain 98% conversion [s] V aq volume aqueous phase [m 3 aq ] V org volume organic phase [m 3 org ] V tot total reaction volume [m 3 ] g volumetric volumetric productivity [mol P .m ±3 .h ±1 ] g enzymatic enzymatic productivity [mol P .g E ±1 .h ±1 ] / j mass transfer rate [mol.m aq ±3 .s ±1 ] n,n eq extent of conversion of aldehyde [%]

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“…(ii) Enzyme-catalyzed cyanohydrin formation has recently been recognized as a powerful tool for the synthesis of intermediates for the preparation of enantiopure pharmaceuticals (Kruse, 1992;Effenberger, 1994).…”

Section: Introductionmentioning

confidence: 99%

Crystallization and preliminary X-ray diffraction studies of a hydroxynitrile lyase fromHevea brasiliensis

Wagner¹,

Schall²,

Hasslacher³

et al. 1996

Acta Cryst D

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Crystals of the hydroxynitrile lyase from Hevea brasiliensis" overexpressed in Pichia pastoris have been obtained by the hanging-drop technique at 294 K with ammonium sulfate and PEG 400 as precipitants. The crystals belong to the orthorhombic space group C2221 with cell dimensions of a = 47.6, b = 106.8 and c = 128.2 A. The crystals diffract to about 2.5 A resolution on a rotating-anode X-ray source.

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Synthese und Reaktionen optisch aktiver Cyanhydrine

Cited by 117 publications

References 120 publications

N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions

N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions

Comparison of a batch, fed-batch and continuously operated stirred-tank reactor for the enzymatic synthesis of (R)-mandelonitrile by using a process model

Crystallization and preliminary X-ray diffraction studies of a hydroxynitrile lyase fromHevea brasiliensis

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