Acetone and formaldehyde

Methyl vinyl ketone can be produced by the reactions of acetone and formaldehyde to form 4-hydroxy-2-butanone, followed by dehydration to the product (267,268). Methyl vinyl ketone can also be produced by the Mannich reaction of acetone, formaldehyde, and diethylamine (269). Preparation via the oxidation of saturated alcohols or ketones such as 2-butanol and methyl ethyl ketone is also known (270), and older patents report the synthesis of methyl vinyl ketone by the hydration of vinylacetylene (271,272). 

Absorption is widely used as a raw material and/or product recovery technique in separation and purification of gaseous streams containing high concentrations of VOC, especially water-soluble compounds such as methanol, ethanol, isopropanol, butanol, acetone, and formaldehyde. Hydrophobic VOC can be absorbed using an amphiphilic block copolymer dissolved in water. However, as an emission control... 

The 1,2-polymerization of 5-methyl-l,4-hexadiene was further confirmed by ozonolysis of the polymer. The resulting solution, after triphenylphosphine treatment, contained only acetone and no detectable formaldehyde by GLC. As shown below in Scheme 1, the volatile products expected by the above chemical treatment of poly(5-methyl-l,4-hexadiene) are acetone and formaldehyde if the polymer was formed by 1,2- and 4,5-polymerization, respectively. 

Anhydroenneaheptitol pentanitrate has found no practical application, since the yield of alcohol is low owing to the fact that in the main acetone and formaldehyde react with one another to form polymers of vinyl methyl ketone (methylene acetone) CH2=CHCOCH3 (Muller [70]). 

Methyl alcohol of very high purity can be obtained by fractional distillation using a column of 1-3 metres effective length and then refluxing with aluminium amalgam. It is then refluxed under a column packed with dehydrated copper sulphate, to remove ammonia. A sensitive test for acetone and formaldehyde is the addition of cone, mercuric cyanide solution, in 6N-sodium hydroxide. A white precipitate indicates ketone if it darkens on standing aldehyde is also present. (J. C. S., 127, 2552.)... 

Irradiation of methoxy-acetone (Formula 254) gives acetone and formaldehyde by a 7-hydrogen transfer in which an oxygen atom makes up part of the ring (107). 

In the induction period the now familiar pattern is again observed. At 295 °C the main products are iso-butyraldehyde and hydrogen peroxide with smaller amounts of acetone and formaldehyde. The onset of pressure increase is accompanied by the formation of acetaldehyde and organic... 

At 400 °C, the formation of acetone and formaldehyde (or perhaps formic acid) in the induction period is more important, while in the subsequent stages formaldehyde formation is again increased relative to the higher homologues (cf. /i-butanol). 

Ri and R2 can be alkyl groups or hydrogen. The oxidation of one tertiary alcohol, terf.-butyl alcohol, has been studied the stoichiometry is uncertain, but acetone and formaldehyde are the main products (section 2.2.5). 

The structure (CCCLXXXII) of this alkaloid, indicated by spectral properties and formation of acetone and formaldehyde on ozonolysis, was confirmed by the synthesis of 0-deacylpachysandrine-B (CCCLXXXV) by treatment of <9,xV-deacylpachysandrine-A (CCCLXXXIV) with jS,/S-dimethylacrylylchloride in pyridine followed by mild alkaline hydrolysis (229). Pachysandrine-B shows behavior analogous to that of pachysan-drine-A. 

Methyl Vinyl Ketone 3-Buten-2-one A3-2 -but-enone methylene acetone acetyl ethylene 3-oxo -a -butyl-ene. C4H(0 mol wt 70.09. C 68.55%, H 8.63%, O 22.83%. CHJCOCH=CHi. Prepn by condensation of acetone and formaldehyde to 3 -keto butanol and dehydration to methyl vinyl ketone Merling Kohler, J. Soc. Chem. Ind 29> 1037 (1910) White, Haward, X Chem. Soc. 1943, 25. Prepn from vinylaoetylene Conaway, U S. pat. 1,967,225 (1934 to du Pont). For review and polymerization characteristics see 4<Vinyl Ketone Polymers in Encyclopedia of Polymer Science and Technology vol. 14 (Interscience, New York, 197]) pp 617-636. 

Partition of the reaction products of the above reaction between CCl.-iF and 80% methanol involved shaking a portion of the supernatant at —78°C. with an equal volume of 80% methanol precooled to —78°C. The aqueous layer, on separation, was rapidly transferred to and mixed with an equal volume of CCbF at —78°C. On separation of the two layers, 2-ml. aliquots were removed from each and analyzed for peracid, acetic acid, hydrogen peroxide, acetone, and formaldehyde in the usual way. The temperature was maintained as close to —78°C. as possible until the analysis stage was reached. The procedure was repeated with CC1 F solutions of the authentic compounds under identical conditions, and partition coefficients were compared. 

The reactants in the key step of an aldol reaction are an enolate anion and an enolate anion acceptor. In self-reactions, both roles are played by one kind of molecule. Crossed aldol reactions are also possible, such as the crossed aldol reaction between acetone and formaldehyde. Because it has no a-hydrogen, formaldehyde cannot form an enolate anion. It is, however, a particularly good enolate anion acceptor because its carbonyl group is unhindered. Acetone forms an enolate anion, but its carbonyl group, which is bonded to two alkyl groups, is less reactive than that of formaldehyde. Consequently, the crossed aldol reaction between acetone and formaldehyde gives 4-hydroxy 2-butanone ... 

Ozonolysis of an alkene produces equal amounts of acetone and formaldehyde, (CH3)2C=0 and CH2=0, respectively. Deduce the alkene structure. 

The hybridization and washing conditions are identical for both paraffin sections and cryosections. However, different steps of treatments prior to hybridization have to be performed for each type of sections (described, respectively, in Subheadings 3.4.3. and 3.5.3.). In the case of paraffin sections, the pretreatments consist of an incubation in an organic solvent to remove the paraffin wax, followed by a mild protease treatment to improve the penetration of probe, and an acetylation step that reduces nonspecific electrostatic binding of the negatively charged probe. In the case of ciyosections, the tissues are postfixed sequentially in acetone and formaldehyde and acetylated as for paraffin sections. 

Other reports deal with a pyrrolidine-catalysed homo-aldol condensation of aliphatic aldehydes (further accelerated by benzoic acid), a diastereoselective aldol-type addition of chiral boron azaenolates to ketones,the use of TMS chloride as a catalyst for TiCU-mediated aldol and Claisen condensations, a boron-mediated double aldol reaction of carboxylic esters, gas-phase condensation of acetone and formaldehyde to give methyl vinyl ketone, and ab initio calculations on the borane-catalysed reaction between formaldehyde and silyl ketene acetal [H2C=C(OH)OSiH3]. ... 

Ratner and Clarke [128] noted that the thiazolidine derived from cysteine and formaldehyde was quite stable to acid. The equilibrium could only be displaced toward the cleavage products by some irreversible process. Presumably the difference in behavior between the acetone and formaldehyde systems reflects the difference in stability of the intermediate cations, (57) (R = R = H R=R = CH3). Cleavage of the formaldehyde system presumably affords a less selective and... 

Selective formation of methyl vinyl ketone over chrysotile was reported through al-dol condensation between acetone and formaldehyde at 673 K, the selectivity being 98% on both acetone and formaldehyde base/ Synthetic Co -containing chrysotile, CoTMg3-T(OH)4Si205, catalyzed the reaction of methanol and acetone to give methyl vinyl ketone and methyl ethyl ketone with 75% selectivity on acetone basis/ ... 

The idea was that sparteine (46) might arise from the double intramolecular Mannich reaction suggested by structure 48 (followed by reduction of the 8-keto group). A precursor of 48 might be 49. In the laboratory, 49 was assembled from piperidine, acetone and formaldehyde via a double intermol-ecular Mannich reaction. Mercuric acetate oxidation of 49 gave 8-ketosparteine (47), presumably via intermediates resembling 48 (stepwise oxidation-Mannich events seem most likely). A Wolff-Kishner reduction of 47 completed the synthesis of 46. Yields were not given for this synthesis and thus, the efficiency of this route (in terms of yield) cannot be evaluated. Efficiency in terms of the number of steps cannot be denied. 

Major products of the OH-initiated oxidation in molar yields (Smith et al 1996) are acetone (70.6%) and 4-oxopentanal (59%). Products of the ozonolysis of 6-methyl-5-hepten-2-one have been quantified by Grosjean et al. (1996c) and Smith et al. (1996) major products include 4-oxopentanal, methylglyoxal, acetone, and formaldehyde. 

---