Carbon Dioxide → HCID 44473618, compound

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Reaction Steps

In a three-neck flask under a protective gas atmosphere, 1,1,3-tris(methylthio)propane (2) (3.65 g, 20 mmol) was dissolved in 50 ml of abs. THF. Subsequently, at −20° C., a butyllithium solution in n-hexane (14 ml, 1.6 M) was slowly added dropwise with stirring. In the course of this, the solution turned bright yellow. After stirring had been continued at this temperature for 2 h, gaseous dry CO2 was passed through via a frit at −70° C. over a period of 30 minutes. The reaction solution was thawed slowly until a temperature of 20° C. was attained, at which a 10% aqueous KOH solution (80 ml) was added. After phase separation, the organic phase was washed with 10% aqueous KOH solution (2×50 ml). The combined KOH phases were washed with diethyl ether (3×30 ml) and then adjusted cautiously to pH 1 with conc. HCl while cooling. The product was extracted with diethyl ether (3×50 ml). The combined ether phases were subsequently dried over Na2SO4 and, after filtration, concentrated on a rotary evaporator. 2,2,4-tris(methylthio)butanoic acid (4) was obtained as a yellowish oil (4.1 g, yield=90%), which crystallized slowly when left to stand. The NMR characterization gave the same data as in Example 3.

Provenance & Evidence