Crystal structure of butyric acid

Abstract

According to single-crystal threc-dimensional X-ray data, n-butyric acid crystals at -43 °C. are monoclinic with a=8.01_+0.08, b=6"82+0"02, c=10.14_+0.03A; fl--lll °27'_+15'.With 4 molecules per unit cell, the calculated density is 1.135 g.cm. -3. This structure exists from the melting point down to about -55 °C. where it changes to a second phase of unknown structure.The structure is described in space group C2/m. The molecules occur as dimers with the oxygen and carbon atoms in the mirror plane, but with large amplitudes for out-of-plane vibrations. A structure in space group C2 is not ruled out by the calculations, but is considered less likely than the structure in C2/m. The bond distances, after corrections of up to 0.03 A for thermal motion, are C-O = 1.22 and 1.35 /~, C-C = 1.54, 1"53 and 1-53 /~ (in order from carboxyl to methyl), each _+ 0.02 A. The hydrogen bond length is 2.62/~.

Synthesis and Molecular Structures of (E)-non-2-enoic Acid and (E)-dec-2-enoic Acid

“…In addition, two crystal structure determinations of co-crystals containing C6 are also known [18,19]. In comparison a complete set of crystal structures of the corresponding saturated carboxylic acids (propionic acid to pentadecanoic acid) is available from the literature [20][21][22][23][24]. In this contribution, we report on the synthesis, characterization and crystal structure determinations of two members of the series of α,β-unsaturated carboxylic acids: (E)-non-2-enoic acid (C9) and (E)-dec-2-enoic acid (C10), respectively, which are linked into centrosymmetric dimers via pairs of O-H···O hydrogen bonds in the crystals.…”

Methyl quantum tunneling and nitrogen-14 NQR NMR studies using a SQUID magnetic resonance spectrometer

“…A spectrum can be obtained in one scan by the SQUID spectrometer (although usually at least one scan in each sweep direction for each resonance is preferred) compared to the many cycles needed for field cycling experiments. Also, the SQUID spectrometer is specifically 132 built to operate at low temperatures, which is a requirement for observation of the tunneling phenomenon. A low temperature field cycling apparatus requires either the shuttling of the sample at 4.2 K ~r changing the field strength of the NMR magnet with the sample in a cryostat.…”

“…Sample crystal structure of propanoic acid. 133 Carbon atoms are shaded, oxygens are patterned. The methyl group is placed between four carboxylic acid dimer groups.…”

Kristallstrukturen von Alkansäuren Interpretation von 2‐ und 3‐dimensionalen Ausschnitten

“…2000/Nr. 4 Molekiilstrangen in der Schichtebene ist eine mittlere Molekiilkette gegenlaufig positioniert und zur Bezugsebene verkantet. Die terminalen Methyl-Gruppen der Alkansaure-Molekule sind dabei annahernd zu den benachbarten Carboxyl-Gruppen ausgerichtet (Abb.…”