3,3-Dimethylacrylic acid

This reaction illustrates the conversion of the —COCH3 group into the —COOH group by means of a hypohalite  

Fit a 1-litre three-necked flask with two double surface condensers and a glycerine-scaled stirrer (Fig. II, 7, 10). Place 25 g. (29 ml.) of mesityl oxide (Section 111,79), 50 ml. of dioxan and a cold (10°) solution 

Maleic acid may be prepared by warming malic acid with acetyl chloride, distilling the mixture under atmospheric pressure to isolate maleic anhydride, and hydrolysing the latter by boding with water. 

Commercially, maleic anhydride is prepared more cheaply by the catalytic vapour phase oxidation (in the presence of vanadium pentoxide at about 400°) of benzene with atmospheric oxygen  

Upon heating with hydrochloric acid, maleic acid, m.p. 144°, is converted into fumaric acid, m.p. 287°  

round-bottomed three-necked flask is equipped with a Kyrides sealed stirrer (Org. Syn. 21, 40, Note 1) and two long condensers, and the apparatus is so arranged that, if necessary, the exit water from the condensers may be quickly used to cool the flask. 

In the flask are placed 200 cc. of dioxane, 100 g. (1.02 moles) of mesityl oxide, and a solution of 4.6 moles of potassium hypochlorite in 3 1. of water (Note 1), and the stirrer is started. The mixture becomes warm immediately, and within five minutes chloroform begins to reflux. When the reaction becomes very vigorous the stirrer is stopped and the flask is cooled with running water (Note 2). The stirring is resumed as soon as feasible and is continued for three or four hours, when the temperature of the mixture will have dropped to that of the room. Sodium bisulfite (about 5 g.) is then added to react with the excess hypochlorite (Note 3). 

The residue is then placed in a modified Claisen flask (Org. Syn. 22, 11) and distilled under reduced pressure. Dimethyl-acrylic acid distils at 100-106°/20 mm. The yield of white solid is 49-53 g. (49-53 per cent of the theoretical amount). This product melts at 60-65°. It may be further purified by recrystallization from petroleum ether (b.p., 60-70°) or water (Note 5). 

The flask is cooled only as much as is necessary to keep the chloroform refluxing gently. After a half hour the reaction will have subsided enough so that no further cooling is necessary. 

When a few cubic centimeters of the solution no longer liberate iodine from a slightly acid potassium iodide solution, enough sodium bisulfite has been added. 

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Dimethylacrylic acid (3-Methyl- 25 5 12 472 Ethylenediainine-N,N -diacetic acid ... 

Prepare a solution containing about 100 g, of potassium hypochlorite from commercial calcium hypochlorite ( H.T.H. ) as detailed under -Dimethylacrylic Acid, Section 111,142, Note 1, and place it in a 1500 ml. three-necked flask provided with a thermometer, a mechanical stirrer and a reflux condenser. Warm the solution to 55° and add through the condenser 85 g, of p-acetonaphthalene (methyl p-naphthyl ketone) (1). Stir the mixture vigorously and, after the exothermic reaction commences, maintain the temperature at 60-70° by frequent cooling in an ice bath until the temperature no longer tends to rise (ca. 30 minutes). Stir the mixture for a further 30 minutes, and destroy the excess of hypochlorite completely by adding a solution of 25 g. of sodium bisulphite in 100 ml. of water make sure that no hypochlorite remains by testing the solution with acidified potassium iodide solution. Cool the solution, transfer the reaction mixture to a 2-litre beaker and cautiously acidify with 100 ml. of concentrated hydrochloric acid. Filter the crude acid at the pump. 

No connection appears to have been traced between the Seneeio alkaloids and the senecioic acid ( /S-dimethylacrylic acid) found by Asahina in Senedo Kaempferi. ... 

Allyl alcohol Crotonaldehyde P -Dimethylacrylic acid Maleic and fumaric acids. ... 

For recrystallization from water, 48-50 g. of the acid is dissolved in 450 cc. of hot water. The solution is cooled in ice for several hburs, and the crystalline precipitate is filtered with suction and dried overnight in a desiccator. The yield of pure dimethylacrylic acid melting at 66-67.5° is 35-40 g., a recovery of 70-83 per cent. 

PP-Dimethylacrylic acid, 460 Dimethylamine hydrochloride, 414, 416 Dimethylaminomethylindole, 1012,1013 P-Dimethylaminopropiophenone hydrochloride, 910, 911... 

It is customary to prepare the ester by reaction of the phenol with an unsaturated acid chloride, generally in the absence of solvents. Again, crotonic and 3,3-dimethylacrylic acid... 

The reaction of 1,3-dihydroxynaphthalene with 3,3-dimethylacrylic acid in the presence of phosphorus oxychloride and zinc chloride yields only 9-hydroxy-2,2-dimethyl-benzo[/]chroman-4-one (585). 2,7-Dihydroxynaphthalene similarly yields the angular ben-zochromanone (586) rather than the alternative linear product (79RRC59). 

The dimethylacrylate 1 is readily available from dimethylacrylic acid. 

Dimethylacrylic acids, ml61, ml62 3,3-Dimethylallene, ml48... 

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). 

Experiment 5.125 3,3-DIMETHYLACRYLIC ACID (3-Methylbut-2-enoic acid)... 

Hexahydrobenzoyl chloride P,p-Dimethylacrylic acid methyl ester Hydroxylamine hydrochloride Sodium hydroxide... 

A mixture of 5-oxo-3-methyl-5-cyclohexylpentene-2 acid 1-methyl ester and 5-oxo-3-methyl-5-cyclohexylpentene-3 acid 1-methyl ester was obtained by condensation of hexahydrobenzoyl chloride with p,p-dimethylacrylic acid methyl ester. 11.2 g of this mixture and a solution of 4.6 g of sodium acetate and 4 g of hydroxylamine hydrochloride were shaken for 20 hours at 25°C with a mixture of 8 ml of water and 15 ml methanol. Subsequently, a solution of 4 g of sodium hydroxide in 8 ml of water was then added, while cooling, shaken for 1 hour at room temperature. The mixture was extracted by means of benzene and the aqueous phase was acidified to reach a pH of 6. 3.5 g of l-hydroxy-4-methyl-6-cyclohexyl-2-pyridone were obtained melting point 144°C. 

Direct evidence for the prototropic route in a substituted crotonic acid was obtained from reactions of j8,j8-dimethylacrylic acid (258) (Owen and Sultanbawa, 1949a). With alkoxides, both unsaturated alkoxy acids (259) and (260) were isolated, and differentiation between the substitution-rearrangement route (258) —(259) - (260) and the rearrangement -> substitution -> rearrangement route (258) (261) - ... 

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