“…([BMIM]PF 6 ) was chosen because of its good stability and excellent performance as a medium in many reactions [15][16][17], for example, in a green route to synthesize a pharmaceutical product [18] in high yield. Acetonitrile, in which pyridoxine has a higher solubility, was chosen as a representative traditional solvent for a comparative study (14). The effects of important factors such as acylating agents, reaction temperature and time, enzyme amount and water activity on the conversion and regioselectivity were investigated.…”
Section: Introductionsupporting
confidence: 90%
“…The HPLC elution program is the same as that for HPLC analysis (see Section 2.5). The characteristic ion peaks of 5-(acetoxymethyl)-3-hydroxy-4-(hydroxymethyl)-2-methylpyridine (abbreviated as 5-monoacetyl pyridoxine) and 4,5-(diacetoxymethyl)-3-hydroxy-2-methylpyridine (abbr., 4,5-diacetyl pyridoxine) for diagnosis were observed and agreed well with previous report [14].…”
Section: Typical Reaction and Identification Of Productsmentioning
confidence: 99%
“…This has been substantially demonstrated by a number of reports [11][12][13]. However, after the pioneering work of Baldessari et al [14], who conducted lipasecatalyzed modification of VB6 in common organic solvents, few reports concerning VB6 have been published so far. Herein, we report lipase-catalyzed regioselective acylation of pyridoxine using 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) as a medium.…”
The regioselective acylation of pyridoxine catalyzed by immobilized lipase (Candida Antarctica) in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) has been investigated, and compared with that in acetonitrile (ACN). The acetylation of pyridoxine using acetic anhydride in [BMIM]PF 6 gave comparable conversion of pyridoxine to 5-monoacetyl pyridoxine with considerably higher regioselectivity (93%-95%) than that in ACN (70%-73%). Among the tested parameters, water activity (a w ) and temperature have profound effects on the reaction performances in either [BMIM]PF 6 or ACN. For the reaction in [BMIM] PF 6 , higher temperature (50uC-55uC) and lower a w (,0.01) are preferable conditions to obtain better conversion and regioselectivity. Mass transfer limitation and intrinsic kinetic from the ionic nature of ionic liquids (ILs) may account for a different rate-temperature profile and a lower velocity at lower temperature in [BMIM]PF 6 -mediated reaction. Moreover, consecutive batch reactions for enzyme reuse also show that lipase exhibited a much higher thermal stability and better reusability in [BMIM]PF 6 than in ACN, which represents another advantage of ILs as an alternative to traditional solvents beyond green technology.
“…([BMIM]PF 6 ) was chosen because of its good stability and excellent performance as a medium in many reactions [15][16][17], for example, in a green route to synthesize a pharmaceutical product [18] in high yield. Acetonitrile, in which pyridoxine has a higher solubility, was chosen as a representative traditional solvent for a comparative study (14). The effects of important factors such as acylating agents, reaction temperature and time, enzyme amount and water activity on the conversion and regioselectivity were investigated.…”
Section: Introductionsupporting
confidence: 90%
“…The HPLC elution program is the same as that for HPLC analysis (see Section 2.5). The characteristic ion peaks of 5-(acetoxymethyl)-3-hydroxy-4-(hydroxymethyl)-2-methylpyridine (abbreviated as 5-monoacetyl pyridoxine) and 4,5-(diacetoxymethyl)-3-hydroxy-2-methylpyridine (abbr., 4,5-diacetyl pyridoxine) for diagnosis were observed and agreed well with previous report [14].…”
Section: Typical Reaction and Identification Of Productsmentioning
confidence: 99%
“…This has been substantially demonstrated by a number of reports [11][12][13]. However, after the pioneering work of Baldessari et al [14], who conducted lipasecatalyzed modification of VB6 in common organic solvents, few reports concerning VB6 have been published so far. Herein, we report lipase-catalyzed regioselective acylation of pyridoxine using 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) as a medium.…”
The regioselective acylation of pyridoxine catalyzed by immobilized lipase (Candida Antarctica) in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) has been investigated, and compared with that in acetonitrile (ACN). The acetylation of pyridoxine using acetic anhydride in [BMIM]PF 6 gave comparable conversion of pyridoxine to 5-monoacetyl pyridoxine with considerably higher regioselectivity (93%-95%) than that in ACN (70%-73%). Among the tested parameters, water activity (a w ) and temperature have profound effects on the reaction performances in either [BMIM]PF 6 or ACN. For the reaction in [BMIM] PF 6 , higher temperature (50uC-55uC) and lower a w (,0.01) are preferable conditions to obtain better conversion and regioselectivity. Mass transfer limitation and intrinsic kinetic from the ionic nature of ionic liquids (ILs) may account for a different rate-temperature profile and a lower velocity at lower temperature in [BMIM]PF 6 -mediated reaction. Moreover, consecutive batch reactions for enzyme reuse also show that lipase exhibited a much higher thermal stability and better reusability in [BMIM]PF 6 than in ACN, which represents another advantage of ILs as an alternative to traditional solvents beyond green technology.
“…Diols can also be selectively monoacylated by treatment with an acylating agent of low reactivity (vinyl, 2,2,2-trifluoroethyl, phenyl, or ethyl esters) in the presence of catalytic amounts of an esterase (Scheme 10.8) [27]. Surprisingly, these enzymatic 338 Scheme 10.7.…”
“…H βιοκαταλυτική σύνθεση εστέρων της βιταμίνης C αλλά και της πυριδοξίνης, χρησιμοποιώντας κορεσμένα ή ακόρεστα λιπαρά οξέα, εστέρες λιπαρών οξέων και τριγλυκερίδια έχει μελετηθεί σε οργανικούς διαλύτες ή συστήματα ελεύθερα διαλυτών [Humeau et al, 1998, Bradoo et al, 1999, Watanabe et al, 1999, Tang et al, 2000, Song & Wei, 2002, Kuwabara et al, 2003, Adamczak et al, 2005, Baldessari et al, 1998, Baldessari & Mangone, 2002, αλλά και σε ιοντικά υγρά , Bai et al, 2008, Chen et al, 2008.…”
Section: μελέτη της δυνατότητας σύνθεσης υβριδικών αντιοξειδωτικών σε ιοντικά υγράunclassified
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