2,3-butanediol formation

CH3C(C6H, ilOHClCfiH,, )0HCH3 (2,3-dicyclohexyl-2,3-butanediol) Formation of 14.3.5.3. 

Fig. 2.17. Acetoin, diacetyl and 2,3-butanediol formation by yeasts in anaerobiosis. TPP = thiamine pyrophosphate TPP-C2 = active acetaldehyde...

The acid end products of fermentation can inhibit growth and butanediol formation. Large quantities of butanediol, up to 130 g/1, were not strongly inhibitory, while 0.45 g/1 of acetic acid can completely inhibit growth of K. oxytoca. Butanediol inhibition is believed to be due to the reduction of water activity, while acetic acid and not its salt is the inhibitory metabolite (Fond et al. 1985). In Enterobacter aerogenes, ethanol was also shown to be an inhibitory metabolite for growth (Zeng and Deckwer 1991). 

FIGURE 7 10 Stereo isomeric 2 3 butanediols shown in their eclipsed con formations for convenience Stereoisomers (a) and (b) are enantiomers of each other Structure (c) is a diastereo mer of (a) and (b) and is achiral It is called meso 2 3 butanediol... 

Reactions with Aldehydes and Ketones. The base-catalyzed self-addition of acetaldehyde leads to formation of the dimer, acetaldol [107-89-1/, which can be hydrogenated to form 1,3-butanediol [107-88-0] or dehydrated to form crotonaldehyde [4170-30-3]. Crotonaldehyde can also be made directiy by the vapor-phase condensation of acetaldehyde over a catalyst (53). 

Shipment, Stora.ge, ndPrice. Tank cars and tank trailers, selected to prevent color formation, are of aluminum or stainless steel, or lined with epoxy or phenoHc resins dmms are lined with phenoHc resins. Flexible stainless steel hose is used for transfer. Because of butanediol s high freezing point (about 20°C) tank car coil heaters are provided. The U.S. Hst price for bulk quantities in 1991 was about 2.18/kg, but heavy discounting was prevalent for large contracts. 

Literature articles, which report the formation and evaluation of difunctional cyanoacrylate monomers, have been published. The preparation of the difunctional monomers required an alternative synthetic method than the standard Knoevenagel reaction for the monofunctional monomers, because the crosslinked polymer thermally decomposes before it can revert back to the free monomer. The earliest report for the preparation of a difunctional cyanoacrylate monomer involved a reverse Diels-Alder reaction of a dicyanoacrylate precursor [16,17]. Later reports described a transesterification with a dicyanoacrylic acid [18] or their formation from the oxidation of a diphenylselenide precursor, seen in Eq. 3 for the dicyanoacrylate ester of butanediol, 7 [6]. 

Since 1,4-butanediol (BD) undergoes dehydration side reaction in the presence of acid resulting in THF formation, the hydroxy-ester interchange reaction is the preferred method for the preparation of PBT. The first stage of reaction is carried out at 150-200°C and consists of a hydroxy-ester interchange between DMT and excess butanediol with elimination of methanol. In the second stage, temperature is raised to 250°C and BD excess is eliminated under vacuum. Tetraisopropoxy-and tetrabutoxytitanium are efficient catalysts for bodi stages (Scheme 2.20). 

The following is an example for a sequential one-pot epoxide formation/nucleophilic opening process using (S)-4-(benzyloxy)-l,2-butanediol, iV-(p-tohienesulfonyl)-imida-zole, and 2-lithio-l,3-dithiane ... 

Detailed studies on the lipase-catalyzed polymerization of divinyl adipate and 1,4-butanediol were performed [41-44]. Bulk polymerization increased the reaction rate and molecular weight of the polymer however, the hydrolysis of the terminal vinyl ester significantly limited the formation of the polyester with high molecular weight. A mathematical model describing the kinetics of this polymerization was proposed, which effectively predicts the composition (terminal structure) of the polyester. 

Significant synthetic applications of the nickel-salen catalysts are the formation of cycloalkanes by reduction of <>, -a-dihaloalkanes255,256 and unsaturated halides,257,258 the conversion of benzal chloride (C6H5CHC12) into a variety of dimeric products 259 the synthesis of 1,4-butanediol from 2-bromo- and 2-iodoethanol260 or the reduction of acylhalides to aldehydes261 and carboxylic acids.262... 

The most important reaction is the oxidative addition of two moles of acetic acid to butadiene to form 1,4-diacetoxy-2-butene (21) with the reduction of Pd2+ to Pd°. In this reaction, 3,4-diacetoxy-l-butene (127) is also formed. In order to carry out the reaction catalytic with regard to Pd2+, a redox system is used. This reaction attracts attention from the standpoint of industrial production of 1,4-butanediol. For this purpose, the formation of 127 should be minimized. Numerous patent applications have been made (examples 113-115), but no paper treating the systematic studies on the reaction has been published. 

In many cases almost quantitative yields are reported for the formation of v/c-dinitrate esters from the reaction of simple alkyl and dialkyl epoxides with dinitrogen pentoxide (Table 3.2). Some of the products formed include ethylene glycol dinitrate (2) (96%), 1,2-propanediol dinitrate (8) (96 %), 2,3-butanediol dinitrate (94 %) and 1,2-butanediol dinitrate (96 %). Reaction times are of the order of 5-15 minutes. 

Because reductions by metals often occur as one-electron processes, radicals are involved as intermediates. When the reaction conditions are adjusted so that coupling competes favorably with other processes, the formation of a carbon-carbon bond can occur. The reductive coupling of acetone to form 2,3-dimethyl-2,3-butanediol (pinacol) is an example of such a process. 

The yield of 1,3-PD for this reaction is 67% (mol/mol). If biomass formation is considered the theoretical maximal yield reduces to 64%. In the actual fermentation a number of other by-products are formed, i. e., ethanol, lactic acid, succinic acid, and 2,3-butanediol, by the enterobacteria Klebsiella pneumoniae, Citrobacter freundii and Enterobacter agglomerans, butyric acid by Clostridium butyricum, and butanol by Clostridium pasteurianum (Fig. 1). All these by-products are associated with a loss in 1,3-PD relative to acetic acid, in particular ethanol and butanol, which do not contribute to the NADH2 pool at all. 

The formation of 1,3-propanediol from glycerol by Klebsiella pneumoniae, Citrobacter and Clostridium butyricum, respectively as well as 2,3-butanediol by Enterobacter aerogenes and their recovery and purification were central issues as well. The production was partly performed in a 2000 litre reactor. Glycerol metabolism in these microorganisms was established. In addition the application of the diols was investigated. 

About 30 years ago, an enthalpy of formation was reported for 3,3,4,4-tetramethyl-l,2-dioxetane . Both by direct microcalorimetric combustion measurements of the neat solid and by reaction calorimetry (of the solid itself, and in acetone solution to form acetone), a consensus value was derived. Now, is the enthalpy of formation plausible , notwithstanding the very large error bars Consider reaction 6 for the dioxetane that produces 2,3-dimethyl-2,3-butanediol . The liquid phase enthalpy of reaction is —329 kJmoU. It is remarkable that this value is compatible with that for the dialkyl peroxides, ca —335 kJmoU, despite the ring strain that might be expected. 

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