Mesityl hydration

Besides acetophenone, this reaction was also applied to p-chloro- andp-methoxyacetophenone, and even to an aliphatic ketone, acetone (although the yield was stated to be only half as large as that obtained from mesityl oxide, i.e., less than 30%, Dorofeenko and co-workers reported a 45% yield of 2,4,6-trimethylpyrylium perchlorate from acetone, acetic anhydride, and perchloric acid), and is the standard method for preparing pyrylium salts with identical substituents in positions 2 and 4. The acylating agent may be an anhydride in the presence of anhydrous or hydrated ferric chloride, or of boron fluoride, or the acid chloride with ferric chloride.Schneider and co-workers ... 

This solid is the first heterogeneous catalyst yet reported for the aldolization of acetone to diacetone alcohol at 273 K. The products of the batch reaction are diacetone alcohol (selectivity > 96 %) and triacetone dialcohol (4 %) with traces of mesityl oxide (MO). The productivity was 3.7 kg DAA kg solid h and the catalyst could be recycled seven times without any loss of activity. Hydrated HDT reached thermodynamic equilibrium in < 1 h and was more active than MgO, calcined HDT, or even solutions of NaOH (Figure 4). The selectivity is also much better because mesityl oxide was not formed on the rehydrated sample. 

By contrast, the reaction of resorcinol with mesityl oxide (2-methylpent-2-ene-one) in the presence of barium hydrate at 150-170°C in vacuo (165-170mm Hg) with azeotropic removal of water during 5 hours has been claimed to afford a 34% yield of 2,2,4-trimethyl-5-hydroxy-2H-chromene rather than the 7-hydroxy isomer (ref.116). 

Hydrated lime is used as an alkaline catalyst to promote the self-condensation of acetone to form diacetone alcohol (4-hydroxy-4-methyl-2-pentanone) [31.26]. Diacetone alcohol is used as a solvent for natural and synthetic resins. It is also used as an intermediate in the produetion of mesityl oxide, methyl isobutyl ketone and hexylene glycol. 

In the hydration of mesityl oxide, the slow step in the sequence appears to be the uptake of a proton by the 2,4-dihydroxy-2-methyI-3-pentene which results from a fast pre-equilibrium hydration of the mesityl oxide. In this situation, however, the rate of the overall reaction does not vary linearly with either [H+ ] or ho at higher acidities this is in keeping with the requisites of the reaction mechanism which is neither strictly A-1 or A-2. ... 

C (10 mmHg). In CeD, the PNMR shift was <5 +159, entirely consistent with the presence of a C=P double bond, and this was confirmed by the C NMR spectrum, which showed phosphorus to be directly coupled to an sp carbon (<5 194.7, Jfc 68.7 Hz) and to an sp carbon 37.1, /pc 51.4 Hz). The 27f-phospholes where the 2-phenyl was replaced by 2,4,6-trimethylphenyl, 2,4,6-trimethoxyphenyl, and methyl were also made in good yield by this method. These 2 -phospholes are thermally stable but very sensitive to water and were hydrated on attempted chromatography on Kieselgel to form the phospholanone (204). Other reactions observed (Scheme 46) included a Diels-Alder cycloaddition with methyl propiolate (giving (205)), and a 1,3-dipolar cycloaddition with mesityl nitrile oxide that formed (206). 

Structure and electronic properties of hydrated mesityl oxide a sequential quantum mechanics/molecular mechanics approach... 

Polarization effects of water on hydrated mesityl oxide... 

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