Hydrochloric Acid → DI-Isopropyl 3-thienylmalonate

Beteiligte Stoffe

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In the way described before 18.8 g (=0.10 mole) di-isopropyl malonate were mono-deprotonated with 0.10 mole NaH in 112.5 ml quinoline. After the liberation of hydrogen gas had been ceased 16.8 g (=0.080 mole) 3-iodothiophene and 11.5 g (=0.080 mole) copper (I) bromide were added. The resultant mixture was stirred under N2 atmosphere at a temperature of 100° C. during a period of 5 hours and subsequently poured out into an icy-cold mixture of 112 ml water and 112 ml concentrated HCl. The precipitated copper salts were collected on a Buchner funnel and washed with chloroform. The filtrate was extracted with chloroform too. The two chloroform layers were joined and dried over magnesium sulphate. After removal of the solvent a residue remained which according to GLC analysis contained 0.44 g 3-iodothiophene and 12 g di-isopropyl 3-thienylmalonate (=0.044 mole or 55% calculated to the 3-iodothiophene started from). A pure sample was obtained by chromatography over a column filled with silica gel using toluene as elution agent. The product so obtained could be crystallized at -18° C. from petroleum ether 40-60; at room temperature, however, it is a liquid. Identification of the purified product occurred through NMR and IR spectroscopy.

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