Diacetone alcohol, formation

Diols yield acetonides, even in the presence of a 17oc-hydroxylgroup. Reaction with acetone in the presence of zinc chloride as catalyst leads to the formation of diacetone alcohol acetal as a by-product. ... 

Purely parallel reactions are e.g. competitive reactions which are frequently carried out purposefully, with the aim of estimating relative reactivities of reactants these will be discussed elsewhere (Section IV.E). Several kinetic studies have been made of noncompetitive parallel reactions. The examples may be parallel formation of benzene and methylcyclo-pentane by simultaneous dehydrogenation and isomerization of cyclohexane on rhenium-paladium or on platinum catalysts on suitable supports (88, 89), parallel formation of mesityl oxide, acetone, and phorone from diacetone alcohol on an acidic ion exchanger (41), disproportionation of amines on alumina, accompanied by olefin-forming elimination (20), dehydrogenation of butane coupled with hydrogenation of ethylene or propylene on a chromia-alumina catalyst (24), or parallel formation of ethyl-, methylethyl-, and vinylethylbenzene from diethylbenzene on faujasite (89a). 

The reaction can, however, be made preparative for (91) by a continuous distillation/siphoning process in a Soxhlet apparatus equilibrium is effected in hot propanone over solid Ba(OH)2 (as base catalyst), the equilibrium mixture [containing 2% (91)] is then siphoned off. This mixture is then distilled back on to the Ba(OH)2, but only propanone (b.p. 56°) will distil out, the 2% of 2-methyl-2-hydroxypentan-4-one ( diacetone alcohol , 91, b.p. 164°) being left behind. A second siphoning will add a further 2% equilibrium s worth of (91) to the first 2%, and more or less total conversion of (90) — (91) can thus ultimately be effected. These poor aldol reactions can, however, be accomplished very much more readily under acid catalysis. The acid promotes the formation of an ambient concentration of the enol form (93) of, for example, propanone (90), and this undergoes attack by the protonated form of a second molecule of carbonyl compound, a carbocation (94) ... 

In the MPVO reaction, several side-reactions can occur (Scheme 20.23). For example, an aldol reaction can occur between two molecules of acetone, which then leads to the formation of diacetone alcohol. The latter acts as a good ligand for the metal of the MPVO catalyst, rendering it inactive. Moreover, the aldol product may subsequently eliminate water, which hydrolyzes the catalyst. The aldol reaction can be suppressed by adding zeolite NaA [84, 92]. 

Cooke and Western [2] postulate that alumina in the soil promotes the formation of diacetone alcohol out in the acetone extract and thus render acetone a doubtful solvent for soil extraction. 

METHYL ISOBUTYL KETONE n-PENTYL FORMATE n-BUTYL ACETATE sec-BUTYL ACETATE tert-BUTYL ACETATE ETHYL n-BUTYRATE ETHYL ISOBUTYRATE ISOBUTYL ACETATE n-PROPYL PROPIONATE CYCLOHEXYL PEROXIDE DIACETONE ALCOHOL 2-ETHYL BUTYRIC ACID n-HEXANOIC ACID 2-ETHOXYETHYL ACETATE HYDROXYCAPROIC ACID PARALDEHYDE... 

AI3-00040, see Cyclohexanol AI3-00041, see Cyclohexanone AI3-00045, see Diacetone alcohol AI3-00046, see Isophorone AI3-00050, see 1,4-Dichlorobenzene AI3-00052, see Trichloroethylene AI3-00053, see 1,2-Dichlorobenzene AI3-00054, see Acrylonitrile AI3-00072, see Hydroquinone AI3-00075, see p-Chloro-rrr-cresol AI3-00078, see 2,4-Dichlorophenol AI3-00085, see 1-Naphthylamine AI3-00100, see Nitroethane AI3-00105, see Anthracene AI3-00109, see 2-Nitropropane AI3-00111, see Nitromethane AI3-00118, see ferf-Butylbenzene AI3-00119, see Butylbenzene AI3-00121, see sec-Butylbenzene AI3-00124, see 4-Aminobiphenyl AI3-00128, see Acenaphthene AI3-00134, see Pentachlorophenol AI3-00137, see 2-Methylphenol AI3-00140, see Benzidine AI3-00142, see 2,4,6-Trichlorophenol AI3-00150, see 4-Methylphenol AI3-00154, see 4,6-Dinitro-o-cresol AI3-00262, see Dimethyl phthalate AI3-00278, see Naphthalene AI3-00283, see Di-rj-butyl phthalate AI3-00327, see Acetonitrile AI3-00329, see Diethyl phthalate AI3-00399, see Tributyl phosphate AI3-00404, see Ethyl acetate AI3-00405, see 1-Butanol AI3-00406, see Butyl acetate AI3-00407, see Ethyl formate AI3-00408, see Methyl formate AI3-00409, see Methanol AI3-00520, see Tri-ocresyl phosphate AI3-00576, see Isoamyl acetate AI3-00633, see Hexachloroethane AI3-00635, see 4-Nitrobiphenyl AI3-00698, see IV-Nitrosodiphenylamine AI3-00710, see p-Phenylenediamine AI3-00749, see Phenyl ether AI3-00790, see Phenanthrene AI3-00808, see Benzene AI3-00867, see Chrysene AI3-00987, see Thiram AI3-01021, see 4-Chlorophenyl phenyl ether AI3-01055, see 1.4-Dioxane AI3-01171, see Furfuryl alcohol AI3-01229, see 4-Methyl-2-pentanone AI3-01230, see 2-Heptanone AI3-01231, see Morpholine AI3-01236, see 2-Ethoxyethanol AI3-01238, see Acetone AI3-01239, see Nitrobenzene AI3-01240, see I idine AI3-01256, see Decahydronaphthalene AI3-01288, see ferf-Butyl alcohol AI3-01445, see Bis(2-chloroethoxy)methane AI3-01501, see 2,4-Toluene diisocyanate AI3-01506, see p,p -DDT AI3-01535, see 2,4-Dinitrophenol AI3-01537, see 2-Chloronaphthalene... 

Aldol condensation of acetone is a well-known base-catalyzed reaction, and barium hydroxide is one of the catalysts for this reaction mentioned in textbooks. A family of barium hydroxide samples hydrated to various degress determined by the calcination temperature (473, 573, 873, and 973 K) of the starting commercial Ba(OH)2 8H2O were reported to be active as basic catalysts for acetone aldol condensation (282,286). The reaction was carried out in a batch reactor equipped with a Soxhlet extractor, where the catalyst was placed. The results show that Ba(OH)2 8H2O is less active than any of the other activated Ba(HO)2 samples, and the Ba(OH)2 calcined at 473 K was the most active and selective catalyst for formation of diacetone alcohol, achieving nearly 58% acetone conversion after 8h at 367 K in a batch reactor. When the reaction temperature was increased to 385 K, 78% acetone conversion with 92% selectivity to diacetone alcohol was obtained after 8h. The yield of diacetone alcohol was similar to that described in the literature in applications with commercial barium hydroxide, but this catalyst required longer reaction times (72-120 h) (287). No deactivation of the catalyst was observed in the process, and it could be used at least 9 times without loss of activity. 

Examples are the formation of diacetone alcohol from acetone [reaction type (A)] catalysed by barium or strontium hydroxide at 20—30°C [368] or by anion exchange resin at 12.5—37.5°C [387], condensation of benzaldehyde with acetophenone [type (C)] catalysed by anion exchangers at 25—-45°C [370] and condensation of furfural with nitromethane [type (D)] over the same type of catalyst [384]. The vapour phase self-condensation of acetaldehyde over sodium carbonate or acetate at 50°C [388], however, was found to be first order with respect to the reactant. 

The Unexpected Formation of l,2-Oxaphosphol-3> ene 2-Oxides in the Reaction of Diacetone Alcohol with Phosphonous Dihalides... 

In all aldol reactions the rate relationship of these two steps is not necessarily the same. The formation of diacetone alcohol from acetone, for example, proceeds with deuterium exchange.4 Consequently, we can conclude that for this reaction, step 2 proceeds at a much slower rate relative to step 1. 

The catalytic formation of diacetone alcohol has been observed in the irradiation of cydopentadienyl manganese tricarbonyl in acetone 473,475) The mechanism of this reaction is unknown possibly, manganese oxides formed in this reaction function as base catalysts in a condensation reaction. 

One of the difficulties in performing aldolization is the reversibility of the reaction, which limits the equilibrium conversion. The thermodynamic equilibrium has been investigated by Craven [2] for the industrially important aldolization of acetone to diacetone alcohol (DA). Because the reaction is exothermic, the yield of aldol obtained from pure acetone decreases with temperature 23.1 % at 273 K, 16.9 % at 283 K, 12.1 % at 293 K and 9.1 % at 303 K. The same conclusions can be drawn from the work of Guthrie [3-6] who reported equilibrium constants in the aqueous phase, in relation to the of the substrates, for a series of aldol condensations at room temperature. For the aldolization of aeetaldehyde at 298 K the values relative to the reaction are AG° = -2.4 kcal mor , A77 = -9.84 kcal mol , and equilibrium constant K = 51 m . The results for a few specific reactions performed in the aqueous phase are reported in Table 1 where Ky and K2 represent the equilibrium constants for the formation of the aldol and for its dehydration, respectively. 

According to these thermodynamic data, significant conversion can be obtained for the condensation of acetone with formaldehyde. Diacetone alcohol can be formed in low yield only and has a lower tendency to dehydrate than the aldols formed from benzaldehyde. The energy balance of the process is so displaced by the formation of water that the unsaturated ketone is usually obtained. The... 

Figure 4. Formation of diacetone alcohol from acetone at 273 K, using NaOH and different solid bases.

A rationalization of the reactions between )8-keto-alcohols and halogenophosphines has been presented by a Russian group. In particular, the reaction between dichloro(phenyl)phosphine (26) and diacetone alcohol to give the oxide (27) has been shown to occur in stages (Scheme 9), and physical and chemical evidence has been presented for the initial formation of mesityl oxide (28) and the acid (29), followed by the addition product (30). A less detailed study of the analogous reaction of chlorodiphenyl-phosphine (5) with diacetone alcohol has also been published. ... 

The product distribution depends also on nPt/hA with pure HZSM5 only mesityioxide (MO) and propene are formed. Both are primary products. Diacetone alcohol (DA) is not observed indicating that its dehydration is very rapid in comparison to its formation by aldolisation of acetone on the acid sites. Only traces of MIBK were found due probably to hydrogen transfer from coke precursors to mesityioxide (MO). 

The treatment of 1,1-dimethyl-3-oxobutanol (diacetone alcohol) with PCI3 in the presence of Et3N leads, even at low temperature, to the formation of much 4-methylpent-3-en-2-one (mesityl oxide) together with moderate amounts of the phosphonic diester 264 when this material is stored, or when it is heated in vacuo, elimination of mesityl oxide occurs and the acid 265 (R = H) results". The outcome of this reaction is somewhat different in the absence of the triethylamine, when the final product is the cyclic phosphinic chloride 266. 

The aldol condensation of two ketones results in the formation of diacetone alcohol. This compound can be dehydrated, and then hydrogenated to give MIBK. 

Tris (ethylenediamine) cadmium dihydroxide Zinc chloride solvent, cellulose acetate Acetylacetone Benzaldehyde Benzyl acetate Butyl formate Cyclohexanone Cyclopentane Diacetone alcohol Diethyl phthalate Ethylbenzene Ethylene glycol acetate... 

Polyvinyl isobutyl ether C6H12O2 Amyl formate n-Butyl acetate s-Butyl acetate t-Butyl acetate Caproic acid Diacetone alcohol Diethylacetic acid Ethyl butyrate Ethyl isobutyrate... 

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