Glycerol production by fermentation

In the context of rapidly depleting petroleum reserves, production of chemicals from renewable carbohydrate-rich resources has assumed importance and a particularly good candidate process is the production of glycerol by fermentation. Of the various osmophilic and nonosmophilic yeasts tested for glycerol yields, two osmophilic yeasts were selected for further studies. The effect of sodium chloride concentration, inoculum size, and nitrogen content of the medium have been investigated. Centrifugation and recycling of cells does not appreciably affect the glycerol yield and fermentation times.     

Fermentation of xylose to glycerol byRhizopus javanicus

Glycerol production from xylose fermentation usingRhizopus javanicus (ATCC 22581) has been investigated in shake flasks. The medium composition (xylose concentration, nitrogen sources), aeration rate, and temperature have been found to affect the accumulation and yield of glycerol. Some of these effects are explained in terms of the critical parameters, osmotic pressure, and dissolved oxygen levels in the medium. Relatively high glycerol yields and concentrations have been obtained at high sugar concentration with high level of aeration at room temperature. The addition of polyethylene glycol or sulfite can improve the yield and accumulation of glycerol.     

Facile synthesis of glycerol carbonate from glycerol using selenium‐catalyzed carbonylation with carbon monoxide

The commercial production of glycerol has increased considerably for several years, because of its rising inevitable formation as a by‐product of biodiesel. For the effective utilization of glycerol, a new synthesis of glycerol carbonate (4‐hydroxymethyl‐2‐oxo‐1,3‐dioxolane) that is used as solvents and raw material of plastics from glycerol was explored. By combined the selenium‐catalyzed carbonylation of slightly excess of glycerol with carbon monoxide and potassium carbonate under 0.1 MPa at 20°C for 4 h in DMF with the oxidation of resulting selenocarbonate salt with molecular oxygen (0.1 MPa, 20 °C) for 2 h, glycerol carbonate was obtained in good yields (83–84%). However, sodium hydride to form sodium alkoxide in situ lowered the yield of glycerol carbonate. Use of triethylamine, 1‐methylpyrrolidine, and DBU as bases gave poor results. Furthermore, styrene carbonate was obtained in excellent yield (90%) under similar reaction conditions. The catalytic synthesis of glycerol carbonate was also brought about in the mixed gas atmosphere (carbon monoxide:oxygen = 3:1, 0.1 MPa, 20°C). Glycerol carbonate and styrene carbonate were obtained in reasonable yields (197% and 119%, based on selenium used). © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:541–545, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20640     

Optimization of media by evolutionary algorithms for production of polyols

Biotransformation of sucrose-based medium to polyols has been reported for the first time using osmophilic yeast, Hansenula anomala. A new, real coded evolutionary algorithm was developed for optimization of fermentation medium in parallel shake-flask experiments. By iteratively employing the nature-inspired techniques of selection, crossover, and mutation for a fixed number of generations, the algorithm obtains the optimal values of important process variables, namely, inoculum size and sugar, yeast extract, urea, and MgSO₄ concentrations. Maximum polyols yield of 76.43% has been achieved. The method is useful for reducing the overall development time to obtain an efficient fermentation process.     

Synthesis of glycerol carbonate from glycerol and urea with gold-based catalysts

The reaction of glycerol with urea to form glycerol carbonate is mostly reported in the patent literature and to date there have been very few fundamental studies of the reaction mechanism. Furthermore, most previous studies have involved homogeneous catalysts whereas the identification of heterogeneous catalysts for this reaction would be highly beneficial. This is a very attractive reaction that utilises two inexpensive and readily available raw materials in a chemical cycle that overall, results in the chemical fixation of CO(2). This reaction also provides a route to up-grade waste glycerol produced in large quantities during the production of biodiesel. Previous reports are largely based on the utilisation of high concentrations of metal sulfates or oxides, which suffer from low intrinsic activity and selectivity. We have identified heterogeneous catalysts based on gallium, zinc, and gold supported on a range of oxides and the zeolite ZSM-5, which facilitate this reaction. The addition of each component to ZSM-5 leads to an increase in the reaction yield towards glycerol carbonate, but supported gold catalysts display the highest activity. For gold-based catalysts, MgO is the support of choice. Catalysts have been characterised by XRD, TEM, STEM and XPS, and the reaction has been studied with time-on-line analysis of products via a combination of FT-IR spectroscopy, HPLC, (13)C NMR and GC-MS analysis to evaluate the reaction pathway. Our proposed mechanism suggests that glycerol carbonate forms via the cyclization of a 2,3-dihydroxypropyl carbamate and that a subsequent reaction of glycerol carbonate with urea yields the carbamate of glycerol carbonate. Stability and reactivity studies indicate that consecutive reactions of glycerol carbonate can limit the selectivity achieved and reaction conditions can be selected to avoid this. The effect of the catalyst in the proposed mechanism is discussed.     

Thermotolerant yeast for simultaneous saccharification and fermentation of cellulose to ethanol

Ten promising microbial strains were screened for glucose fermentation over the temperature range of 37–47°C, and five temperature-tolerant yeasts (Saccharomyces cerevisiae SERI strain (D₅A),S. uvarum, andCandida generaacidothermophilium, brassicae, andlusitaniae), were chosen for SSF evaluation on Sigmacell-50 cellulose with Genencor 150 L cellulase enzyme.Brettanomyces clausenii (Y-1414) was included for comparison to previous studies both by itself and in mixed culture withS. cerevisiae (D₅A). Good conversion rates were achieved at temperatures as high as 43°C withC. brassicae andS. uvarum; mixed cultures of either of these yeasts with the thermotolerant cellobiose fermenting yeastC. lusitaniae achieved higher rates and yields than any of the three yeasts alone. However, the mixed culture ofB. clausenii andS. cerevisiae at 37°C achieved as high conversion rates and higher yields than any of the other yeasts tested.     

Oxiranylmethyl-Fragmentierung zur Bildung von Cyclopentadecan-1,5-dion-Derivaten. Eine Musconsynthese

The Formation of Cyclopentadecane-1,5-dione Derivatives by an Oxiranylmethyl Fragmentation. A Synthesis of Muscone A new method for the preparation of cyclopentadecane-1,5-dione ( 11 ) and its 3-methylderivative 12 , compounds with a musk fragrance, is described. Starting from the readily available bicyclic enones 9 and 10 , the epoxy-p-toluenesulfonate 15 and its methylderivatives 20A and 20B were prepared by reduction with diisobutyl-aluminium hydride or sodium borohydride (to 13 and 18A , 18B ), epoxidation with m-chloroperbenzoic acid (to 14 and 19A , 19B ), followed by tosylation. Heating of 15 and 20A or 20B with calcium carbonate in water/dioxane under reflux caused fragmentation leading to the diketones 11 and 12 in high yields. The same fragmentation also occurred with sodium hydrogencarbonate in dimethylsulfoxide at 160°, but in lower yields. The conversion of 12 into rac-muscone ( 2 ) was accomplished by developing a method for selectively forming the monotosylhydrazone 27 . The latter was reduced with sodium borohydride and the crude alcohol 28 oxidized to 2 . Unexpectedly the pyrolysis of the epoxy-acetate 29 at 350° in a sealed glass tube led to the bicyclic ketone 10 . Treatment of 3-methylcyclopentadecane-1,5-dione ( 12 ) with peracetic acid and boron trifluoride etherate gave the stable crystalline ozonide 33 .     

RAPID REDUCTION OF CARBONYLS WITH NICKEL BORIDE AT AMBIENT TEMPERATURE[1]

Carbonyl compounds have been reported to undergo rapid reduction with nickel boride generated in situ from anhyd. nickel chloride and sodium borohydride in THF at ambient temperature to the corresponding alcohols in high yields.     

Synthesis of 4,6,8-Trisubstituted Methyl Azulene-2-carboxylates

It is shown that sodium (methoxycarbonyl)cyclopentadienide ( 1 ), which is easily accessible from sodium cyclopentadienide and dimethyl carbonate in THF, reacts with 2,4,6-trisubstituted pyrylium tetrafluoroborates 2a–d in boiling MeOH to afford the corresponding methyl azulene-2-carboxylates 4a–d in good yields. The corresponding 1-carboxylates 3 were not found (cf. Schemes 1 and 2).     

Introducing Water and Deep Eutectic Solvents in Organosodium Chemistry: Chemoselective Nucleophilic Functionalizations in Air

Advancing the development of perfecting the use of polar organometallics in bio-inspired solvents, we report on the effective generation in batch of organosodium compounds, by the oxidative addition of a C−Cl bond to sodium, a halogen/sodium exchange, or by direct sodiation, when using sodium bricks or neopentylsodium in hexane as sodium sources. C(sp³)-, C(sp²)-, and C(sp)-hybridized alkyl and (hetero)aryl sodiated species have been chemoselectively trapped (in competition with protonolysis), with a variety of electrophiles when working “on water”, or in biodegradable choline chloride/urea or L-proline/glycerol eutectic mixtures, under hydrous conditions and at room temperature. Additional benefits include a very short reaction time (20 s), a wide substrate scope, and good to excellent yields (up to 98 %) of the desired adducts. The practicality of the proposed protocol was demonstrated by setting up a sodium-mediated multigram-scale synthesis of the anticholinergic drug orphenadrine.     

Pd-catalyzed reaction of allyl carbonate with polyols: the role of CO2 in transesterification versus etherification of glycerol

An intermolecular Pd/PPh(3)-catalyzed transesterification of diallyl carbonate with glycerol to generate glycerol carbonate has been developed. Analysis of the reaction kinetics in THF indicates a first-order dependence on Pd and diallyl carbonate, that the Pd bears two phosphines during the turnover limiting event, and that increasing the glycerol concentration inhibits reaction, possibly via change in the polarity of the medium. (13)C isotopic labeling studies demonstrate that the Pd-catalyzed transesterification requires at least one allyl carbonate moiety and that there is rapid equilibrium of the allyl carbonate with CO(2) in solution, even when present only at low concentrations. A mechanism that is consistent with these results involves oxidative addition of the allyl carbonate to Pd followed by reversible decarboxylation, with the intermediate η(1)- and η(3)-allyl Pd alkoxides mediating direct and indirect transesterification reactions with the glycerol. Using this model, successful simulations of the kinetics of reactions conducted under atmospheres of N(2) or CO(2) could be achieved, including switching in selectivity between etherification and transesterification in the early stages of reaction. Reactions with the higher polyols threitol and erythritol are also efficient, generating the terminal (1,2) monocarbonates with high selectivity.     

Pd‐Catalyzed Reaction of Allyl Carbonate with Polyols: The Role of CO2 in Transesterification versus Etherification of Glycerol

An intermolecular Pd/PPh₃‐catalyzed transesterification of diallyl carbonate with glycerol to generate glycerol carbonate has been developed. Analysis of the reaction kinetics in THF indicates a first‐order dependence on Pd and diallyl carbonate, that the Pd bears two phosphines during the turnover limiting event, and that increasing the glycerol concentration inhibits reaction, possibly via change in the polarity of the medium. ¹³C isotopic labeling studies demonstrate that the Pd‐catalyzed transesterification requires at least one allyl carbonate moiety and that there is rapid equilibrium of the allyl carbonate with CO₂ in solution, even when present only at low concentrations. A mechanism that is consistent with these results involves oxidative addition of the allyl carbonate to Pd followed by reversible decarboxylation, with the intermediate η¹‐ and η³‐allyl Pd alkoxides mediating direct and indirect transesterification reactions with the glycerol. Using this model, successful simulations of the kinetics of reactions conducted under atmospheres of N₂ or CO₂ could be achieved, including switching in selectivity between etherification and transesterification in the early stages of reaction. Reactions with the higher polyols threitol and erythritol are also efficient, generating the terminal (1,2) monocarbonates with high selectivity.     

Bacillus stearothermophilus for thermophilic production of l-lactic acid

A process for the continuous production of high purityL-lactic acid in a membrane bioreactor at 65°C has been developed. Two differentBacillus stearothermophilus strains have been tested in batch experiments. Lactic acid yields are between 60 and more than 95% of theoretical yields. The amounts of ethanol, acetate, and formate formed varied between 0 and 0.4, 0 and 0.1, and 0 and 0.5, respectively (mol/mol glucose). All byproducts are valuable and may be separated easily by rectification of the fermentation broth. Complete cell retention enables high volumetric productivity (5 g/Lh), and a minimum of growth supplements. The high temperature of 65°C allows the autoselective fermentation without problems with contamination.     

A facile synthesis of new β-lactams

Several new β-lactams have been synthesized in good yields, via the cyclization of 3-chloro-N-arylpropionamides in a mixture of N, N-dimethylformamide and anhydrous sodium carbonate under a nitrogen atmosphere.     

Utilization of hypervalent iodine in organic synthesis: A novel and facile two‐step protocol for the synthesis of new derivatives of 1H‐Imidazo[1,2‐b]pyrazole by the cyclocondensation involving α‐Tosyloxyacetophenones

A series of new 2‐aryl‐7‐cyano/ethoxycarbonyl‐6‐methylthio‐1H‐imidazo[1,2‐b]pyrazoles ( 5 ) have been synthesized in moderate to good yields, via a two‐step cyclocondensation procedure of 5‐amino‐4‐cyano/ethoxycarbonyl‐3‐methylthio‐1H‐pyrazole ( 1 ) and α‐bromoacetophenones ( 3 ) or α‐tosyloxyacetophenones ( 2 ), which were prepared by the reactions of acetophenones with [hydroxy(tosyloxy)iodo]benzene (HTIB). The intermediates, 5‐amino‐1‐(aroylmethyl)‐4‐ cyano/ethoxycarbonyl‐3‐methylthio‐1H‐pyrazoles ( 4 ), have been isolated, serving as evidence for the regioselectivity. When utilizing α‐tosyloxy‐acetophenones, the reactions were more eco‐friendly, the reaction time was significantly reduced and the synthetic procedure was more convenient and easier to manipulate. Surprisingly, using potassium carbonate to displace sodium carbonate in the synthesis of 4 , in the case of 1 (R? CN), two novel cyclocondensation products have been isolated and fully characterized, followed by the proposal of a plausible mechanism.     

Ligand-free, atom-efficient Suzuki-Miyaura type cross-coupling reactions at room temperature

The atom-efficient cross-coupling reaction of sodium tetraarylborates with aryl iodides and bromides was reported. The reaction can be performed directly using a catalytic system composed of palladium chloride, sodium carbonate and methanol (PdCl₂/Na₂CO₃/MeOH) under heat-free conditions at room temperature in an open air conditions. The reactions carried out in an atom-efficient way as 4 equiv of aryl halides coupled effectively with 1 equiv of sodium tetraarylborates to furnish 4 equiv of the corresponding functionalized biaryls in good to excellent yields.     

Chemical recycling of post-consumer PET wastes by glycolysis in the presence of metal salts

Chemical recycling of poly(ethylene terephthalate) (PET) has been the subject of increased interest as a valuable feedstock for different chemical processes. In this work, glycolysis of PET waste granules was carried out using excess ethylene glycol in the presence of different simple chemicals acting as catalysts, namely zinc acetate, sodium carbonate, sodium bicarbonate, sodium sulphate and potassium sulphate. Comparable high yields (≈70%) of the monomer bis(2-hydroxyethyl terephthalate) were obtained with zinc acetate and sodium carbonate as depolymerisation catalysts at 196 °C with a PET:catalyst molar ratio of 100:1 in the presence of a large excess of glycol. The purified monomer was characterised by elemental analysis, differential scanning calorimetry, infrared spectroscopy, and nuclear magnetic resonance. These results revealed that, although the intrinsic activity of zinc acetate was significantly higher than that of sodium carbonate, this latter salt could indeed act as an effective, eco-friendly catalyst for glycolysis. Also an exploratory study on the application of this catalytic recycling technology for complex PET wastes, namely highly coloured and multi-layered PET, was performed.     

Efficient 1,3-propanediol Production by Fed-Batch Culture of Klebsiella Pneumoniae: The Role of pH Fluctuation

The fermentative production of 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae under different fed-batch strategies was investigated. pH-stat fed-batch strategies proved to be not effective for economical 1,3-PD production for the existence of relatively high concentration of byproducts and residual glycerol at the end of the fermentation. However, in the pH-stat fed-batch strategy, an important phenomenon was observed that the yields of two main byproducts, 2,3-butanediol and lactic acid, were closely related to pH value. The dominant byproduct was 2,3-butanediol at a pH value of 5.0 to 6.5 but changed to be lactic acid at a pH value of 7.1 to 8.0. Based on the analysis of the phenomenon, a self-protection mechanism in K. pneumoniae, namely that the growing K. pneumoniae cells switch the metabolic pathways responding to environmental pH changes, was proposed. Thus a kind of feeding strategy was further applied during which the pH value was fluctuated between 6.3 and 7.3 periodically by feeding glycerol–ammonia mixture and sulphuric acid to make the metabolic pathways of 2,3-butanediol and lactic acid sub-active under the periodical low or high pH stress. At last, efficient 1,3-PD production was fulfilled under this fed-batch strategy, and the best results were achieved leading to 70 g/l 1,3-PD with a yield of 0.70 mol/mol glycerol and productivity of 0.97 g/l/h, while the two main byproducts and residual glycerol were under low concentrations.     

Synthesis and structure of some substituted 2-amino-4-aryl-7-propargyloxy-4H-chromene-3-carbonitriles

A series of 2-amino-7-hydroxy-4H-chromene-3-carbonitriles 4a–l were synthesized through three-component reaction using sodium carbonate as a catalyst. The reaction was carried out in 96% ethanol-water medium (1:20 ratio in volume). Propargyl ether compounds 5a–l of these chromene-3-carbonitriles were successfully synthesized from corresponding hydroxyl chromene derivatives by reaction with propargyl bromide. Two different procedures were applied in this process: the procedure that used potassium carbonate in dried acetone and the procedure that used sodium hydride in dried DMF. The latter gave the ethers 5a–l in higher yields. The single-crystal X-ray structure of propargyl ether 5g has been recorded.     

丙三醇碳酸酯的电合成研究

在常温常压下,采用电化学方法,以丙三醇和CO₂为原料合成了丙三醇碳酸酯,并详细考察了各种条件对该反应的影响规律. 择优条件下,目标碳酸酯的产率可达73%,远远高于普通的催化方法. 并借助循环伏安曲线研究了反应体系的电化学行为,分析了整个反应的可能历程.