Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava ...Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was <30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was >53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.展开更多
3-(Pyrrole-2?-carboxamido)propanoic acid I has been synthesized from the reaction of β-alanine methyl ester with 2-trichloroacetylpyrrole followed by saponifying and acidating in 85.4% yield, and the crystal structur...3-(Pyrrole-2?-carboxamido)propanoic acid I has been synthesized from the reaction of β-alanine methyl ester with 2-trichloroacetylpyrrole followed by saponifying and acidating in 85.4% yield, and the crystal structure of 3-(pyrrole-2?-carboxamido)propanoic acid· (1/2)H2O (C8H11N2O3.5, Mr = 191.19) was obtained and determined by X-ray diffraction method. The crystal is of monoclinic, space group C2/c with a = 19.010(4), b = 8.3515(17), c = 13.788(3) ?, β = 125.88(3)o, V = 1773.6(6) ?3, Z = 8, Dc = 1.432 g/cm3, λ = 0.71073 ?, μ(MoKα) = 0.114 mm?1 and F(000) = 768. The structure was refined to R = 0.0354 and wR = 0.0942 for 1642 observed reflections with I > 2σ(I). It is revealed that the title compound has one pyrrole ring and one propionic acid subchain linked by an amido bond at C(4), and there are 8 molecules of com- pound I and 4 crystal water molecules in each unit cell. The supramolecular layers are stabilized by the hydrogen bonds of N(2) H…O(2), N(1) H…O(4), O(4) H(1W)…O(2) and O(3) H…O(1).展开更多
3-(Trichlorogermyl)propanoic acid (1a) reacts with phenylmagnesium bromide in molar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a). In the compounds 1a and 2a the β-carboxylic functional group shows some un...3-(Trichlorogermyl)propanoic acid (1a) reacts with phenylmagnesium bromide in molar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a). In the compounds 1a and 2a the β-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide. The compound 1a reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give 1,1-diphenyl-3–(triphenylgermyl)propanol (4a). The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also. Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy. Moreover, the compound la reacted with phenylmagnesium bromide in molar ratio 1:6, then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3 (triphenylgermyl)-1-propene (5a) in one pot reaction. Alkyl Ge–C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride (LiAlH4) in good yield.展开更多
基金Supported by the National High Technology Research and Development Program of China (2008AA10Z338)
文摘Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was <30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was >53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.
基金The project was supported by the National 863 Program of China(No.2004AA628030)Natural Science Foundation of Guangdong Province(No.31920)
文摘3-(Pyrrole-2?-carboxamido)propanoic acid I has been synthesized from the reaction of β-alanine methyl ester with 2-trichloroacetylpyrrole followed by saponifying and acidating in 85.4% yield, and the crystal structure of 3-(pyrrole-2?-carboxamido)propanoic acid· (1/2)H2O (C8H11N2O3.5, Mr = 191.19) was obtained and determined by X-ray diffraction method. The crystal is of monoclinic, space group C2/c with a = 19.010(4), b = 8.3515(17), c = 13.788(3) ?, β = 125.88(3)o, V = 1773.6(6) ?3, Z = 8, Dc = 1.432 g/cm3, λ = 0.71073 ?, μ(MoKα) = 0.114 mm?1 and F(000) = 768. The structure was refined to R = 0.0354 and wR = 0.0942 for 1642 observed reflections with I > 2σ(I). It is revealed that the title compound has one pyrrole ring and one propionic acid subchain linked by an amido bond at C(4), and there are 8 molecules of com- pound I and 4 crystal water molecules in each unit cell. The supramolecular layers are stabilized by the hydrogen bonds of N(2) H…O(2), N(1) H…O(4), O(4) H(1W)…O(2) and O(3) H…O(1).
基金Project supported by the National Natural Science Foundation of China
文摘3-(Trichlorogermyl)propanoic acid (1a) reacts with phenylmagnesium bromide in molar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a). In the compounds 1a and 2a the β-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide. The compound 1a reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give 1,1-diphenyl-3–(triphenylgermyl)propanol (4a). The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also. Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy. Moreover, the compound la reacted with phenylmagnesium bromide in molar ratio 1:6, then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3 (triphenylgermyl)-1-propene (5a) in one pot reaction. Alkyl Ge–C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride (LiAlH4) in good yield.
