Influence of glucose solubility and dissolution rate on the kinetics of lipase catalyzed synthesis of glucose laurate in 2-methyl 2-butanol.
The lipase catalyzed acylation of glucose by dodecanoic acid in 2-methyl 2-butanol was studied. The initial reaction rate was strongly dependent on the dissolved glucose concentration in the medium. Several methods were shown to increase dissolved glucose concentrations and initial reaction rates, namely, the use of solid beta-glucose, amorphous solid glucose, and supersaturated glucose solution. Supersaturated glucose solutions in 2-methyl 2-butanol showed a high stability even in the presence of solid crystalline glucose. During the reaction, the dissolved glucose concentration falls as the reaction proceeds, before recovering later as more of the excess solid dissolves. However, the ester synthesis rate continues to fall even after glucose concentration reaches its minimum, so glucose dissolution rate limitation is not responsible for the synthesis rate decline. Experiments with added molecular sieves show that the main reason is the accumulation of product water. In the presence of molecular sieves, 70% of glucose was converted to ester, independent of the initial soluble glucose in the medium.
Flores
Maria Victoria
MV
Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, UK. Maria.Flores@strath.ac.uk
Naraghi
Kaynoush
K
Engasser
Jean-Marc
JM
Halling
Peter J
PJ
D000215:Acylation; D000440:Butanols / Q000737:chemistry*; D002384:Catalysis; D004800:Enzymes, Immobilized; D004951:Esterification; D004952:Esters / Q000138:chemical synthesis; D005656:Fungal Proteins; D005947:Glucose / Q000737:chemistry*; D007848:Laurates / Q000737:chemistry*; D007850:Lauric Acids / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D000439:Pentanols; D012680:Sensitivity and Specificity; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000440:Butanols; D004800:Enzymes, Immobilized; D004952:Esters; D005656:Fungal Proteins; D007848:Laurates; D007850:Lauric Acids; D000439:Pentanols; D012996:Solutions; D014867:Water; C030358:lauric acid; C032765:tert-amyl alcohol; D008049:Lipase; C431349:lipase B, Candida antarctica; D005947:Glucose