Mesityl oxide preparation

Mesityl oxide is an industrial chemical prepared by an aldol condensation. From what organic starting material is mesityl oxide prepared It often contains about 10% of an isomer with the same carbon skeleton. What Is the most likely structure for this contaminant ... 

The residual liquid contains about 95 per cent, of diacetone alcohol and is satisfactory for the preparation of mesityl oxide (Section 111,79). 

It la of Interest to note that the preparation of dimethyldihydroresorcinol (also named dlmedone and methone Section VII, 15) involves an initial Dchael addition to mesityl oxide, followed by an internal Claiaen condensation. 

Ma.nufa.cture. Mesityl oxide is produced by the Hquid-phase dehydration of diacetone alcohol ia the presence of acidic catalysts at 100—120°C and atmospheric pressure. As a precursor to MIBK, mesityl oxide is prepared ia this manner ia a distillation column ia which acetone is removed overhead and water-saturated mesityl oxide is produced from a side-draw. Suitable catalysts are phosphoric acid (177,178) and sulfuric acid (179,180). The kinetics of the reaction over phosphoric acid have been reported (181). 

Diacetunamine has been prepared in satisfactory yields by treating a mixture of commercial acetone and calcium chloride with anhydrous ammonia. The preparation from commercial acetone and ammonia is laborious and gives low yields. No yields are given in the older published descriptions of the preparation from mesityl oxide with either aqueous or anhydrous ammonia. The method described here has recently been published. ... 

A number of dihydroquinolines have been prepared by treating aniline derivatives with acetone or mesityl oxide in the presence of iodine. In these cases aromatization to the fully unsaturated quinoline would require the loss of methane, a process known as the Riehm quinoline synthesis. Such Skraup/Doebner-von Miller-type reactions are often low yielding due to large amounts of competing polymerization. For example, aniline 37 reacts with mesityl oxide to give dihydroquinolines 39, albeit in low yield. ... 

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 ... 

Compound 68 can also be obtained by an acid-catalyzed cyclization of 42, which was prepared by the Michael addition reaction of 39 to mesityl oxide as shown in Section IV.A. As for the product 69, the presence of the tosyloxy group at the 5 position instead of the 6 position is determined, utilizing the anisotropy effect of the 1-acetyl group to the C-7 proton, by comparing its H NMR spectrum with that of 70, obtained in 69% yield by the treatment of 69 with NaH and AcCl. 

A number of methods for the preparation of III were examined. Best results were obtained using a modification of the procedure of Surmatls, et al. (10) A mixture of 1.00 mole of mesityl oxide,... 

Trimethylpyrylium perchlorate has been prepared from 2,6-dimethylpyrone and methylmagnesium halides 6 from mesityl oxide and sulfoacetic acid 6 from mesityl oxide (or less satisfactorily from acetone) and a mixture of acetic anhydride and perchloric acid 7 from mesityl oxide, acetyl chloride, and aluminum chloride 8 and from <-butyl chloride, acetyl chloride,... 

Synthetic methods. / / -Dimethylglutaric acid (prepared from mesityl oxide) was converted into the di-silver salt, which, by an improvement of the method of Windaus and Klanhardt, was converted into / / -dimethyl-y-butyrolactone. The latter on treatment with constant-boiling hydrobromic and sulphuric acid gave y bromo /i/ dimethylbutyric acid which readily gave its ethyl ester. The pure fluoro ester was obtained from this by heating with silver fluoride, although the yield was low. 

The material is prepared by Diels-Alder reaction of 1,3-pentadiene and mesityl oxide and subsequent aldol condensation of the resulting acetyl trimethyl cyclohexene with acetaldehyde [99]. 5-Damascone is used in perfumes to create masculine notes. 

The preparation of the material starts from of mesityl oxide and ethyl acetoacetate which are cyclized under acidic conditions. The resulting ethyl 4-oxo-2,6,6-trimethyl-2-cyclohexenecarboxylate is subsequently reduced and dehydrated. 

The preparation of iV-nitroso-/5-alkylaminoisobutyl ketones is of particular interest as a method for preparing the intermediates for the diazoalkane synthesis. The preparation of these compounds is based on the addition of a primary amine to mesityl oxide to give a secondary amino ketone which is then nitrosated (see Volume I, Chapter 15, Section 2A,g). This preparation uses an... 

Nitrosation of mesityl oxide oxime leads to the dioxide 96, correctly formulated by Freeman.119 Earlier workers had formulated the product as a nitrimine128 and as a nitrosonitrone.118 Hypobromite oxidation of 97 leads to the same compound129 (Scheme 35), whereas the 4-bromo analog of 96 has been prepared by base elimination of HBr from a dibromopyrazoline N,N -dioxide precursor.119... 

Improvements in the double Skraup synthesis of 1,7-phenanthroline from m-phenylenediamine now enable a yield of 70% to be achieved.163 The Skraup reaction continues to be used for the synthesis of 1,7-phen-anthrolines starting from the substituted 5-aminoquinolines. S-Chloro-6-hydroxy-1,7-phenanthroline (18) has been prepared in this way,164 and an improved synthesis of 6-hydroxy-1,7-phenanthroline was reported.165 As expected, the Skraup reaction on 5-aminoquinaldine affords 8-methyl-1,7-phenanthroline,166 not 2-methyl-1,7-phenanthroline as it was previously named.8 The extension of the Skraup reaction using methyl vinyl ketone instead of glycerol has been applied to 5-aminoquinoline to afford 4-methyl-1,7-phenanthroline.166 A related condensation using 2-hydroxymethylenecyclohexanone provides a route to benzo-substituted 1,7-phenanthrolines.167 7-Aminoquinoline with mesityl oxide in the presence of iodine gives 8,8,10-trimethyl-7,8-dihydro-l,7-phenanthroline (19).168... 

The crude diacetone alcohol is prepared according to the directions in Exp. IX (p. 45). The acetone recovered from the preparation of mesityl oxide can be mixed with fresh acetone and successfully used in preparing more crude diacetone alcohol. 

The methods of making mesityl oxide fall into three classes (1) the action of condensing agents (hydrochloric acid, etc.) on acetone 1 (2) the dehydration of diacetone alcohol 2 (3) and from diacetonamine.3 The latter method was not considered since the amine is relatively difficult to prepare. The action of acid condensing agents on acetone is very unsatisfactory the yields are poor and considerable quantities of phorone and similar substances are invariably produced. The direct production... 

The oily layer is separated from the aqueous layer, the aqueous layer is extracted with two 200-ml. portions of ether, and the combined extracts and oil are dried over calcium chloride. The drying agent is removed by filtration, and the ether is distilled on a water bath finally, all low-boiling material is removed from the mixture on a boiling water bath under the lowest pressure obtainable with a water pump (Note 6). The nitrosoaminoketone which remains in the flask is sufficiently pure for the preparation of diazomethane (Note 7). The yield is 221-257 g. (70-80% based on mesityl oxide). 

Hydroxy-4-methyl-4-penten-2-one (1) was prepared from 3-chloro-mesityl oxide using a modified procedure from the literature [ref.4], A reference sample of 4-methyl-4-penten-2,3-dione (2) was prepared from using the copper acetate method [ref.2], 4-methyl-pentan-2,3-dione (3) was purchased from Wiley Co. 2-Hydroxy-4-methyl-4-penten-3-one (4) was synthesized in 30% yield from 2-propenyl-magnesium bromide and 2-hydroxy-propionitrile in tetrahydrofurane. The structures of all compounds were confirmed by H-. C-NMR- and mass spectroscopy [ref. 5],... 

For The preparation of 4-methyl-4-penten-2,3-dione from 3,4-epoxy-mesityl oxide see A.L. Shabanov M.M. Movsumzade, S.S. Muradova and I. Rats, Dokl. Acad. Nauk. Azerb. SSR 27 (1971), 42 Chem. Abstr. 76 (1972), 153169f. 

In the examples given the preparative value depends upon the ready availability of the required methyl ketone thus pinacolone (Expt 5.98), cyclopropyl methyl ketone (Expt 7.1) and mesityl oxide (Expt 5.213) are converted into 2,2-dimeth-ylpropanoic acid, cyclopropanecarboxylic acid and 3,3-dimethylacrylic acid respectively (Expts 5.124 and 5.125). 

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