Malonic acid

About: Malonic acid is a research topic. Over the lifetime, 3129 publications have been published within this topic receiving 41686 citations. The topic is also known as: Malonate & Propanedioic acid.

Radiation Damage in Organic Crystals. I. CH(COOH)2 in Malonic Acid1

Abstract: An analysis of the electron magnetic resonance of single crystals of malonic acid that were subjected to x-ray damage indicates that: (a) the principal long-lived paramagnetic species produced by the x-ray darnage is gen atoms of this radical are oriented in the crystalline lattice in the same way as these atoms are arranged in the parent undamaged malonic acid molecule. (c) The z,x,y components of the diagonal (electron-spin) - (nuclear-spin) coupling dyadic for the proton attached to the alpha -carbon atom are found to be of the same relative sign and of magnitudes 29. 61, and 91 Mc, respectively. In this orthogonal axis system, z is the CH bond direction and x is perpendicular to the plane of the three carbon atoms. These results are in excellent agreement with theoretical values of the distributed dipole and contact hyperfine interactions and show that this molecule is a pi -electron radical, that the unpaired electron is concentrated almost entirely on the alpha -carbon and that the spin density on the in-plane sigma -proton is negative. The observed g-factors for this radical are g/sub x/ = 2.0026, g/sub y/ = 2.0035, and g/sub z/ = 2.0033 and are in good qualitative agreement withmore » previous theoretical estimates of these quantities. (auth)« less

Molecular Complexes of Homologous Alkanedicarboxylic Acids with Isonicotinamide: X-ray Crystal Structures, Hydrogen Bond Synthons, and Melting Point Alternation

Abstract: Crystallization of α,ω-alkanedicarboxylic acids (HOOC−(CH2)n-2−COOH, n = 2−6) with isonicotinamide (IN) is carried out in 1:2 and 1:1 stoichiometry. Five cocrystals of (diacid)·(IN)2 composition (diacid = oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) are characterized by X-ray diffraction at 153(2) K. Tapes of acid−pyridine O−H···N and amide−amide N−H···O hydrogen bond synthons stabilize these five crystal structures as predicted by the hierarchic model: the best donor (COOH) and best acceptor group (pyridine N) hydrogen bond as acid−pyridine and the second best donor−acceptor group (CONH2) aggregates as an amide dimer. Glutaric acid and adipic acid cocrystallize in 1:1 stoichiometry also, (diacid)·(IN), with acid−pyridine and acid−amide hydrogen bonds. Synthon energy calculations (ΔEsynthon, RHF/6-31G**) explain the observed hydrogen bond preferences in 1:2 (five examples) and 1:1 (two examples) cocrystals. The acid−pyridine hydrogen bond is favored over the acid−amide dimer ...