Initiator butanedione

Direct oxidation yields biacetyl (2,3-butanedione), a flavorant, or methyl ethyl ketone peroxide, an initiator used in polyester production. Ma.nufa.cture. MEK is predominandy produced by the dehydrogenation of 2-butanol. The reaction mechanism (11—13) and reaction equihbtium (14) have been reported, and the process is in many ways analogous to the production of acetone (qv) from isopropyl alcohol. 

Photolytic. Glyoxal, methylglyoxal, and biacetyl were produced from the photooxidation of 1,2,3-trimethylbenzene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of 1,2,3-trimethylbenzene and OH radicals at room temperature was 1.53 x 10 " cmVmolecule-sec (Hansen et al., 1975). A rate constant of 1.49 x 10 L/molecule-sec was reported for the reaction of 1,2,3-trimethylbenzene with OH radicals in the gas phase (Darnall et al., 1976). Similarly, a room temperature rate constant of 3.16 x 10 " cm /molecule-sec was reported for the vapor-phase reaction of 1,2,3-trimethylbenzene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 2.69 x lO " cm /molecule-sec was reported for the same reaction (Ohta and Ohyama, 1985). 2,3-Butanedione was the only products identified from the OH radical-initiated reaction of 1,2,4-trimethylbenzene in the presence of nitrogen dioxide. The amount of 2,3-butanedione formed decreased with increased concentration of nitrogen dioxide (Bethel et al., 2000). 

Shortly after the discovery of photochemical air pollution, Stephens and his co-workers (Stephens et al., 1956 Stephens, 1987) applied long-path infrared spectroscopy to identifying and measuring products in the photooxidation of organic-NO, mixtures. In the photooxidations of 3-methylheptane and, to a larger extent, 2,3-butanedione, a set of infrared bands that could not be assigned to known products was observed. These were assigned to a previously unobserved species, which was initially called compound X. It was ultimately shown to be peroxyacetyl nitrate (PAN) ... 

There are also examples of the use of compounds that are converted into diketones under the conditions of the Pfitzinger reaction and then react with isatins. Thus, the diacid 56 (yield 58%) was obtained from 2-hydroxy-3-butanone and isatin 7 in the presence of potassium hydroxide in water [26], while the dicarboxylic acids 58 were synthesized from 3-chloro-2-butanone and isatins 57 [44], The initial chloro ketone is clearly saponified to 2-hydroxy-3-butanone under the reaction conditions. As in the reaction with isatin 7, the product is then oxidized to 2,3-butanedione, which reacts with two molecules of isatin. 

Simple diketones such as 2,3-butanedione are rapidly deprotonated by 02, but the original diketone is recovered upon acidification (equation 144). However, benzil (PhCO-COPh) cannot enolize and is dioxygenated by O2 to give two benzoate ions (equation 145). Carbon dioxide reacts rapidly with 02 in aprotic solvents with a net stoichiometry in acetonitrile (equation 146) and the proposed reaction path involves an initial nucleophilic addition (equation 147). 

Copolymers of 2,3-butanedione-2-< -methacryloyl-oxime with MMA [poly (BOMA-co-MMA)], containing different amounts (7-30 mol%) of side-chain O-acyloxime moieties, have also been used [75] as macro-initiators for the photochemical grafting of styrene and acrylamide in benzene and dioxane solution, respectively,... 

Riordan (1973) has reported that the monomer of 2,3-butanedione inactivates carboxypeptidase as effectively as the trimer. One interesting feature of his study is that a 0.05 M borate buffer enhances the rate and possibly affects the distribution of products formed from both monomeric and trimeric butanedione when compared with a 0.05 M veronal buffer at the sample pH. He has attributed this specific buffer effect to the formation of a cyclic borate ester following the initial condensation of the guanidinium group with 2,3-butanedione as indicated in eq. (3.1). The conditions of modification with butanedione used by Riordan (1973) involved incubation of the protein at pH 7.5 at 20°C for 15-60 min at concentrations of butanedione ranging from 2.2 x 10 M to 7.5 X 10-2... 

Proposed reaction scheme for 2,3-butanedione and ammonium sulfide is summarized in Figure 6. Since there was no acetaldehyde involved in this model reaction, we proposed that the initial step of cleavage of 2,3-butanedione would required to form an acetaldehyde and an acetamide which was similar to the mechanism described by Grimmett and Richards (P) for the interaction of pyruvaldehyde and ammonia in an ammoniacal environment. Thioacetamide was formed as the result of addition of H2S to acetamide. In fact, the presence of 1,2,4-trithiolanes and 1,3,5-trithiane in the reaction mixture also explained the... 

Fresh perspiration is odorless. The smells we associate with perspiration result from a chain of events initiated by bacteria that are always present on our skin. These bacteria produce lactic acid, which creates an acidic environment that allows other bacteria to break down the components of perspiration, producing compounds with the unappealing odors we associate with armpits and sweaty feet. One such compound is butanedione. 

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