Synthesis and Molecular Structures of the Lowest Melting Odd- and Even-Numbered ,-Unsaturated Carboxylic Acids—(E)-Hept-2-Enoic Acid and (E)-Oct-2-Enoic Acid

The molecular structures of the two lowest melting oddand even-numbered α,β-unsaturated carboxylic acids—(E)-hept-2-enoic acid (C7) and (E)-oct-2-enoic acid (C8)—are herein reported. The title compounds were crystallized by slow evaporation of ethanolic solutions at ́30 ̋C. C7 crystallizes in the triclinic space group P1 with two molecules in the unit cell and C8 in the monoclinic space group C2/c with eight molecules in the unit cell. The unit cell parameters for C7 are: a = 5.3049(2) Å, b = 6.6322(3) Å, c = 11.1428(5) Å, α = 103.972(3) ̋, β = 97.542(3) ̋, γ = 90.104(3) ̋, and V = 376.92(3) Å3 (T = 150(2) K). The unit cell parameters for C8 are: a = 19.032(10) Å, b = 9.368(5) Å, c = 11.520(6) Å, β = 123.033(11) ̋, and V = 1721.80(16) Å3 (T = 200(2) K).