Conformational Properties of Model Compounds of Imide-Ether Molecular Chains

1994 ◽  
Vol 27 (26) ◽  
pp. 7689-7694
Author(s):  
M. L. Jimeno ◽  
J. G. de la Campa ◽  
E. Riande ◽  
J. de Abajo ◽  
J. M. Garcia
Keyword(s):  
Model Compounds ◽  
Conformational Properties

Calculations of the Effects of Substituents on the Conformations of Pbzt and Pbo Model Compounds

1988 ◽  
Vol 134 ◽  
Author(s):  
B. L. Farmer ◽  
Scott G. Wierschke ◽  
W. W. Adams
Keyword(s):  
Phenyl Ring ◽  
Critical Parameter ◽  
Molecular Orbital Calculations ◽  
Methyl Ethyl ◽  
Model Compounds ◽  
X Ray ◽  
Torsional Potential ◽  
Conformational Properties ◽  
Conformational Freedom ◽  
Conformational Energies

ABSTRACTSemiempirical energy calculations have been used to investigate the conformational properties of poly(p-phenylene benzobisthiazole) (PBZT) and poly(p-phenylene benzobisoxazole) (PBO) having various substituents on the phenyl ring. Substituents considered included methyl, ethyl, t-butyl, hydroxyl, phenyl, and benzthiazole groups. The torsional potential for rotation about the backbone bond joining the phenylene and heterocyclic rings has a significant influence on the conformational energies. X-ray structure data and results of semiempirical molecular orbital calculations were used to determine this critical parameter.The results show that most substituents have surprisingly little influence on the conformations of the molecules. In most cases, the substituent causes a rotation of the backbone rings away from coplanarity, but once the steric interactions are relieved, there is considerable latitude for further rotation. The substituents most effective in locking the molecules into specific conformations were hydroxyl and t-butyl, due, respectively, to the prospect for hydrogen bonding, and non-planarity. In most cases, the conformational freedom is such that packing considerations could significantly influence the conformations of the materials in the solid state.

The conformational properties of calix[4]arenes 1h NMR and molecular mechanics calculations

1989 ◽  
Vol 86 ◽  
pp. 945-954 ◽  
Author(s):  
F. Bayard ◽  
D. Decoret ◽  
D. Pattou ◽  
J. Royer ◽  
A. Satrallah ◽  
...  
Keyword(s):  
Molecular Mechanics ◽  
1H Nmr ◽  
Molecular Mechanics Calculations ◽  
Conformational Properties

Structure Revision of Protoaculeine B, a Posttranslationally Modified N-Terminal Residue in the Peptide Toxin Aculeine B

2020 ◽  
Author(s):  
Raku Irie ◽  
Kei Miyako ◽  
Satoko Matsunaga ◽  
Ryuichi Sakai ◽  
Masato Oikawa
Keyword(s):  
Mass Spectra ◽  
Chemical Reactivity ◽  
Model Compounds ◽  
Structural Revision ◽  
Structure Revision ◽  
Peptide Toxin ◽  
One Step ◽  
Marine Peptide ◽  
Synthetic Models ◽  
Long Chain

<div>Here, we newly propose the structure of protoaculeine B, an N-terminal moiety of the marine peptide toxin aculeine B, as possessing the cis-disubstituted tetrahydro-beta-carboline framework. We prepared two truncated model compounds that lack long-chain polyamine by one-step Pictet-Spengler reaction of tryptophan, and compared the NMR and mass spectra and chemical reactivity with those of natural protoaculeine B. The synthetic models reproduced the profiles of the natural product well, which was conclusive for the structural revision.</div>

Lignin to Value-Added Chemical Synthesis

2020 ◽  
Vol 16 ◽  
Author(s):  
Mahdieh Sharifi ◽  
Ramyakrishna Pothu ◽  
Rajender Boddula ◽  
Inamuddin
Keyword(s):  
Ionic Liquids ◽  
Lignocellulosic Biomass ◽  
Academic Research ◽  
Power Saving ◽  
Value Added ◽  
Glycerol Ether ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Biomass Activity ◽  
Lignin Model

Background: There is a developing demand for innovation in petroleum systems replacements. Towards this aim, lignocellulosic biomass suggested as a possible sustainable source for the manufacturing of fuels and produced chemicals. The aims of this paper are to investigate different kinds of β-O-4 lignin model compounds for the production of value-added chemicals in presence of ionic liquids. Especially, a cheap β-O-4 lignin model Guaiacol glycerol ether (GGE) (Guaifenesin) is introduced to produce valuable chemicals and novel products. Methods: Research related to chemical depolymerization of lignocellulosic biomass activity is reviewed, the notes from different methods such as thermal and microwave collected during at least 10 years. So, this collection provides a good source for academic research and it gives an efficient strategy for the manufacturing of novel value-added chemicals at an industrial scale. Results: This research presented that ionic liquid microwave-assisted is a power saving, cost efficient, fast reaction, and clean way with high selectively and purity for production of high value chemicals rather that conversional heating. Guaiacol and catechol are some of these valuable chemicals that is produced from β-O-4 lignin model compounds with high word demands that are capable to produce in industry scale. Conclusion: The β-O-4 lignin model compounds such as Guaiacol glycerol ether (GGE) (Guaifenesin) are good platform for developing food materials, perfumery, biorefinery, and pharmaceutical industry by ionic liquids-assisted lignin depolymerization method.

Study on the precision of the activated charcoal solvent desorption procedure - Correlation of desorption efficiencies

1981 ◽  
Vol 46 (6) ◽  
pp. 1332-1347 ◽  
Author(s):  
Martin Koval
Keyword(s):  
Activated Charcoal ◽  
Carbon Disulphide ◽  
Internal Standard ◽  
Standard Addition ◽  
Published Data ◽  
Single Factor ◽  
Gas Chromatograph ◽  
Model Compounds ◽  
Single Factor Analysis ◽  
Acceptable Agreement

The described method uses activated charcoal sampling tubes for air sampling. Adsorbed compounds are eluted by the static desorption procedure with 1 ml of carbon disulphide, 0.5 ml of the supernatant is filtered off and, after internal standard addition, analysed on a gas chromatograph. Using synthetic calibration mixtures of model organic compounds with air, cumulative sampling and desorption efficiencies for 24 substances were determined for concentration ranges and sample volumes according to current Czechoslovak hygienic standards. Experimental results were treated with the single factor analysis of variance and the precision of the described procedure was estimated for the studied model compounds on the basis of residual sums of squares. Calculated values of cumulative sampling and desorption efficiencies and their precisions were compared with available published data and an acceptable agreement was found. In addition to that, cumulative sampling and desorption efficiencies were also found to be significantly correlated to molar volumes and other related molecular properties for some types of compounds.

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