Search in database (English)
Dimethyl sulfoxide was distilled from calcium hydride at a pressure of about 1 mm. Sodium methoxide was used without purification. Diethyl phthalate was distilled under vacuum. In the condensation reaction described here it is important to use only anhydrous reagents since water has a deleterious effect due to the hydrolysis of the phthalate ester to phthalic acid.
Sodium methoxide (5.4 g., 0.1 mole) was suspended in 75 ml. of anhydrous dimethyl sulfoxide in a 250-ml. round-bottomed flask under an atmosphere of nitrogen. The suspension was stirred by a stream of nitrogen introduced by a gas inlet tube extending to the bottom of the flask. Diethyl phthalate (5.5 g., 0.025 mole) was added dropwise to this suspension. The reaction mixture, which turned yellow after about 5 min., was kept under nitrogen for 4 hr. at room temperature after which it was subjected to vacuum distillation at 1-mm. pressure (bath temperature 65—70°) for 50 min. To the resulting sticky yellow residue 50 ml. of ether and 50 ml. of ice-water were added. The yellow aqueous layer was separated and added dropwise with stirring to a mixture of 60 ml. of water and 40 ml. of concentrated hydrochloric acid. The colorless precipitate which formed rapidly was removed by filtration and dried under vacuum to give 2-chloro-2-methylmercapto-1,3-indandione, 4.55 g. (80%), m.p. 63°. A sample recrystallized from ether containing a trace of ethanol had m.p. 63—64°.
Anal. Calcd. for C10H7ClO2S; C, 52.90; H, 3.25; Cl, 15.44; S, 14.38; mol. wt., 226.6. Found: C, 53.0; H, 3.10; Cl, 15.61; S, 14.13; mol. wt., 226 (dioxane).
The infrared absorption of 2-chloro-2-methylmercapto-1,3-indandione gave the characteristic indandione absorption at 5.70 and 5.85 μ as well as absorption due to the carbon-sulfur bond at 8.05 μ. Absorption characteristic of a sulfoxide at 9.8 μ was absent.
The integrated n.m.r. (60 Mc./sec. [60 MHz]) spectrum gave aromatic hydrogen (unresolved), intensity 4.0, at 481 cycles [8.02 ppm] relative to tetramethylsilane and methyl hydrogens, (singlet) at τ = 7.52, intensity 3.
© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru