Enthalpies of formation of 2-methyl-2-ethoxypropane and 2-ethyl-2-ethoxypropane from equilibrium measurements

Abstract The equilibria for the synthesis of C 2 H 5 OC(CH 3 ) 3 (A) and C 2 H 5 OC(CH 3 ) 2 (C 2 H 5 ) (B) from C 2 H 5 OH (C) and CH 2 :C(CH 3 ) 2 (D) or CH 3 CH:C(CH 3 ) 2 (E) in the liquid phase were investigated at temperatures from 313 K to 412 K. On the basis of experimental equilibrium constants found for n (C)/ n (D) or n (C)/ n (E) ≥ 4, the following values were obtained for Δ r H m °/(kJ·mol −1 ) and Δ r S m °/(J·K −1 ·mol −1 ): (C + D = A),−(35.45 ± 1.94) and −(82.37 ± 5.99); (C + A = B), −(34.13 ± 0.81) and −(87.82 ± 2.18). The following values of Δ f H m °(298.15 K)/(kJ·mol −1 ) have been derived: C 2 H 5 OC(CH 3 ) 3 (1),−(350.8 ± 2.6); C 2 H 5 OC(CH 3 ) 2 (C 2 H 5 )(1), −(379.8 ± 1.4).