scholarly journals Characterization of autohydrolysis aspen (P. tremuloides) lignins. Part 3. Infrared and ultraviolet studies of extracted autohydrolysis lignin

1979 ◽  
Vol 57 (19) ◽  
pp. 2603-2611 ◽  
Author(s):  
Miranda G. S. Chua ◽  
Morris Wayman
Keyword(s):  
Carboxylic Acid ◽  
Blocking Agent ◽  
Acid Group ◽  
Hydroxybenzoic Acid ◽  
Aspen Wood ◽  
Carboxylic Acid Group ◽  
Carboxylic Acid Groups ◽  
Acidic Conditions ◽  
Lignin Macromolecule

Infrared and ultraviolet studies of the lignins extracted from extractive-free aspen wood meal after autohydrolysis at 195 °C for periods varying from 5 min to 2 h indicated that these lignins were functionally modified and different from aspen milled wood lignin. The extracted lignins changed from a guaiacyl–syringyl type lignin to a syringyl-deficient type lignin with increasing autohydrolysis time. Extracted lignins were also observed to contain unconjugated β-ketone groups and conjugated carboxylic acid groups. It is proposed that the unconjugated β-ketone groups resulted from the depolymerization reactions of the lignin macromolecule under acidic conditions which formed monomeric, dimeric, and oligomeric/polymeric lignin fragments with Hibbert's ketone side chains. The conjugated carboxylic acid group observed to be present was attributed to p-hydroxybenzoic acid. p-Hydroxybenzoic acid has been postulated as contributing to the extractability of aspen lignin by acting as a blocking agent in the repolymerization of lignin fragments to form insoluble lignin.

scholarly journals Crystal structure of betulinic acid methanol monosolvate

2014 ◽  
Vol 70 (12) ◽  
pp. o1242-o1243 ◽  
Author(s):  
Wei Tang ◽  
Neng-Hua Chen ◽  
Guo-Qiang Li ◽  
Guo-Cai Wang ◽  
Yao-Lan Li
Keyword(s):  
Carboxylic Acid ◽  
Solvent Molecule ◽  
Acid Group ◽  
Carboxylic Acid Group ◽  
Syzygium Jambos ◽  
Carboxylic Acid Groups ◽  
Pentacyclic Triterpenoid ◽  
Naturally Occurring ◽  
Dimensional Network ◽  
Chinese Medicinal Plant

The title compound [systematic name: 3β-hydroxylup-20(29)-en-28-oic acid methanol monosolvate], C30H48O3·CH3OH, is a solvent pseudopolymorph of a naturally occurring plant-derived lupane-type pentacyclic triterpenoid, which was isolated from the traditional Chinese medicinal plantSyzygium jambos(L.) Alston. The dihedral angle between the planes of the carboxylic acid group and the olefinic group is 12.17 (18)°. TheA/B,B/C,C/DandD/Ering junctions are alltrans-fused. In the crystal, O—H...O hydrogen bonds involving the hydroxy and carboxylic acid groups and the methanol solvent molecule give rise to a two-dimensional network structure lying parallel to (001).

scholarly journals Crystallographic and spectroscopic characterization of (R)-O-acetylmandelic acid

2016 ◽  
Vol 72 (7) ◽  
pp. 901-903
Author(s):  
Cady Cirbes ◽  
Joseph M. Tanski
Keyword(s):  
Hydrogen Bonding ◽  
Carboxylic Acid ◽  
Mandelic Acid ◽  
Phenylacetic Acid ◽  
Spectroscopic Characterization ◽  
Acid Group ◽  
Intermolecular Hydrogen Bonding ◽  
Carboxylic Acid Group ◽  
Donor Acceptor

The title compound [systematic name: (R)-(−)-2-acetoxy-2-phenylacetic acid], C10H10O4, is a resolved chiral ester derivative of mandelic acid. The compound contains an acetate group and a carboxylic acid group, which engage in intermolecular hydrogen bonding, forming chains extending parallel to [001] with a short donor–acceptor hydrogen-bonding distance of 2.676 (2) Å.

Synthesis and Characterization of Novel Monoazo Naphthalimide Disperse Dyes Containing Carboxylic Acid Group with High Heat Fastness Properties

2008 ◽  
Vol 55 (6) ◽  
pp. 1300-1307 ◽  
Author(s):  
Moosa Sadeghi Kiakhani ◽  
Kamaladin Gharanjig ◽  
Mokhtar Arami ◽  
Javad Mokhtari ◽  
Niyaz Mohammad Mahmoodi
Keyword(s):  
Carboxylic Acid ◽  
Acid Group ◽  
High Heat ◽  
Synthesis And Characterization ◽  
Disperse Dyes ◽  
Fastness Properties ◽  
Carboxylic Acid Group

scholarly journals The first structural characterization of the protonated azacyclam ligand in catena-poly[[[(perchlorato)copper(II)]-μ-3-(3-carboxypropyl)-1,5,8,12-tetraaza-3-azoniacyclotetradecane] bis(perchlorate)]

2019 ◽  
Vol 75 (11) ◽  
pp. 1700-1704
Author(s):  
Liudmyla V. Tsymbal ◽  
Vladimir B. Arion ◽  
Yaroslaw D. Lampeka
Keyword(s):  
Carboxylic Acid ◽  
Metal Ion ◽  
Macrocyclic Ligand ◽  
Acid Group ◽  
Distorted Octahedral Geometry ◽  
Equatorial Orientation ◽  
Carboxylic Acid Group ◽  
Bond Lengths ◽  
Distorted Octahedral

The asymmetric unit of the title compound, catena-poly[[[(perchlorato-κO)copper(II)]-μ-3-(3-carboxypropyl)-1,5,8,12-tetraaza-3-azoniacyclotetradecane-κ4 N 1,N 5,N 8,N 12] bis(perchlorate)], {[Cu(C13H30N5O2)(ClO4)](ClO4)2} n , (I), consists of a macrocyclic cation, one coordinated perchlorate anion and two perchlorate ions as counter-anions. The metal ion is coordinated in a tetragonally distorted octahedral geometry by the four secondary N atoms of the macrocyclic ligand, the mutually trans O atoms of the perchlorate anion and the carbonyl O atom of the protonated carboxylic acid group of a neighbouring cation. The average equatorial Cu—N bond lengths [2.01 (6) Å] are significantly shorter than the axial Cu—O bond lengths [2.379 (8) Å for carboxylate and average 2.62 (7) Å for disordered perchlorate]. The coordinated macrocyclic ligand in (I) adopts the most energetically favourable trans-III conformation with an equatorial orientation of the substituent at the protonated distal 3-position N atom in a six-membered chelate ring. The coordination of the carboxylic acid group of the cation to a neighbouring complex unit results in the formation of infinite chains running along the b-axis direction, which are crosslinked by N—H...O hydrogen bonds between the secondary amine groups of the macrocycle and O atoms of the perchlorate counter-anions to form sheets lying parallel to the (001) plane. Additionally, the extended structure of (I) is consolidated by numerous intra- and interchain C—H...O contacts.

scholarly journals Crystallographic and spectroscopic characterization of 4-nitro-2-(trifluoromethyl)benzoic acid and 4-nitro-3-(trifluoromethyl)benzoic acid

2019 ◽  
Vol 75 (4) ◽  
pp. 524-528
Author(s):  
George L. Diehl III ◽  
Lisa Je ◽  
Joseph M. Tanski
Keyword(s):  
Hydrogen Bonding ◽  
Carboxylic Acid ◽  
Benzoic Acid ◽  
Nitro Group ◽  
Spectroscopic Characterization ◽  
Acid Group ◽  
Carboxylic Acid Group ◽  
Donor Acceptor ◽  
Graph Set

The title compounds, both C8H4F3NO4, represent two isomers of nitro trifluoromethyl benzoic acid. The compounds each contain a nitro functionality para to the carboxylic acid group, with the trifluoromethyl substituent ortho to the acid group in the 2-isomer and ortho to the nitro group in the 3-isomer. The regiochemistry with respect to the trifluoromethyl group results in steric interactions that rotate the carboxylic acid group or the nitro group out of the aromatic plane in the 2- and 3-isomer, respectively. Each molecule engages in intermolecular hydrogen bonding, forming head-to-tail dimers with graph-set notation R 2 2(8) and donor–acceptor hydrogen-bonding distances of 2.7042 (14) Å in the 2-isomer and 2.6337 (16) in the 3-isomer. Recrystallization attempts did not yield untwinned crystals.

scholarly journals 4-Bromo-2-hydroxybenzoic acid

IUCrData ◽  
2016 ◽  
Vol 1 (3) ◽  
Author(s):  
P. A. Suchetan ◽  
V. Suneetha ◽  
S. Naveen ◽  
N. K. Lokanath ◽  
P. Krishna Murthy
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Aromatic Ring ◽  
Title Compound ◽  
Acid Group ◽  
Hydroxybenzoic Acid ◽  
Carboxylic Acid Group ◽  
One Dimensional ◽  
Compound C

In the title compound, C7H5BrO3, the dihedral angle between the aromatic ring and the carboxylic acid group is 4.8 (4)°, and an intramolecular O—H...O hydrogen bond closes anS(6) ring. In the crystal, carboxylic acid inversion dimers linked by pairs of O—H...O hydrogen bonds generateR22(8) loops. Short Br...Br contacts [3.4442 (5) Å] between the molecules of the adjacent dimers leads to a one-dimensional architecture.

scholarly journals Ozone-driven daytime formation of secondary organic aerosol containing carboxylic acid groups and alkane groups

2011 ◽  
Vol 11 (16) ◽  
pp. 8321-8341 ◽  
Author(s):  
S. Liu ◽  
D. A. Day ◽  
J. E. Shields ◽  
L. M. Russell
Keyword(s):  
Carboxylic Acid ◽  
Los Angeles ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Group Formation ◽  
Organic Aerosol ◽  
Acid Group ◽  
Oxidation Products ◽  
Carboxylic Acid Group ◽  
Carboxylic Acid Groups

Abstract. Carboxylic acids are present in substantial quantities in atmospheric particles, and they play an important role in the physical and chemical properties of aerosol particles. During measurements in coastal California in the summer of 2009, carboxylic acid functional groups were exclusively associated with a fossil fuel combustion factor derived from factor analysis of Fourier transform infrared spectroscopic measurements and closely correlated with oxygenated organic factors from aerosol mass spectrometry measurements. The high fraction of acid groups and the high ratio of oxygen to carbon in this factor suggest that this factor is composed of secondary organic aerosol (SOA) products of combustion emissions from the upwind industrial region (the ports of Los Angeles and Long Beach). Another indication of the photochemically-driven secondary formation of this combustion-emitted organic mass (OM) was the daytime increase in the concentrations of acid groups and the combustion factors. This daytime increase closely tracked the O3 mixing ratio with a correlation coefficient of 0.7, indicating O3 was closely associated with the SOA maximum and thus likely the oxidant that resulted in acid group formation. Using a pseudo-Lagrangian framework to interpret this daytime increase of carboxylic acid groups and the combustion factors, we estimate that the carboxylic acid groups formed in a 12-h daytime period of one day ("Today's SOA") accounted for 25–33 % of the measured carboxylic acid group mass, while the remaining 67–75 % (of the carboxylic acid group mass) was likely formed 1–3 days previously (the "Background SOA"). A similar estimate of the daytime increase in the combustion factors suggests that "Today's SOA" and the "Background SOA" respectively contributed 25–50 % and 50–75 % of the combustion factor (the "Total SOA"), for a "Total SOA" contribution to the OM of 60 % for the project average. Further, size-resolved spectrometric and spectroscopic characterization of the particle OM indicate that the majority of the OM formed by condensation of gas-phase oxidation products. This unique set of measurements and methods to quantify and characterize photochemically and ozone-linked carboxylic acid group formation provide independent and consistent assessments of the secondary fraction of OM, which could result from second generation products of the oxidation of gas-phase alkane (molecules).

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