Molecular weight and aggregation of Aeromonas gum treated with dimethyl sulfoxide in aqueous solution

2002 ◽  
Vol 40 (19) ◽  
pp. 2269-2276 ◽  
Author(s):  
Xiaojuan Xu ◽  
Lina Zhang ◽  
Takashi Norisuye
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Dimethyl Sulfoxide

SYNTHESIS OF ISOTOPICALLY LABELLED OLEFINS VIA THE WITTIG REACTION

1965 ◽  
Vol 43 (5) ◽  
pp. 1614-1624 ◽  
Author(s):  
J. G. Atkinson ◽  
M. H. Fisher ◽  
D. Horley ◽  
A. T. Morse ◽  
R. S. Stuart ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dimethyl Sulfoxide ◽  
Wittig Reaction ◽  
Low Molecular Weight ◽  
Phosphonium Salts ◽  
Reaction Conditions ◽  
Selective Labelling ◽  
Wittig Reactions

A new application of the Wittig reaction to the preparation of olefins of low molecular weight which allows selective labelling in the vinyl or allyl positions with isotopes of hydrogen and carbon has been developed. Using the modification of the Wittig reaction introduced by E. J. Corey, in which a solution of the methylsulfinyl carbanion in dimethyl sulfoxide serves as the base, a series of olefins from C2 to C8 were synthesized. The synthesis was applied to the preparation of the following labelled compounds: 5-methylene-14C-bicyclo[2.2.1]hept-2-ene; propene-1-14C; 1-butene-1-14C; propene-1-d1; 2-methylpropene-1,1-d2; 2-methyl-d3-propene-3,3,3-d3; 2-methyl-2-butene-4,4,4-d3; 2-methyl-d3-2-butene-1,1,1-d3; methylene-d2-cyclohexane. For the synthesis of carbon-labelled olefins the reaction has few limitations since the intermediates and products are isotopically stable under the reaction conditions. Deuterium-labelled olefins can be obtained from deuterated formaldehyde or β-deuterated phosphonium salts, but α-deuteroketones and aldehydes and α-deuterophosphonium salts lose the isotope to the solvent.In all the Wittig reactions, benzene was formed as a by-product in 10–15% yield. The mechanism of benzene formation is probably analogous to that proposed by Seyferth involving the decomposition of a pentacovalent phosphorous intermediate.

scholarly journals Purification of acrylamide from polymerization inhibitors in the manufacture of high quality flocculants based on polyacrylamide

2020 ◽  
Vol 3 (2) ◽  
pp. 109-113
Author(s):  
V. P. Duleba ◽  
◽  
Z. Ya. Hnativ ◽  
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Polymerization Process ◽  
Iron Ions ◽  
Laboratory Studies ◽  
Catalytic Method ◽  
High Quality ◽  
Variable Valence ◽  
Sulfuric Acid Method ◽  
Practical Information

Polyacrylamide and its copolymers are widely used as flocculating agents for the separation of industrial suspensions. The formation of high molecular weight polymers depends on the content of various impurities present in the monomer. The article presents the scientific and practical information on the production of acrylamide by sulfuric acid method of hydration of nitrile acrylic acid in the form of an aqueous solution of different concentrations and a more modern heterogeneously catalytic method of hydration of acrylonitrile using as catalysts with variable valence. Ways to get different impurities in the stages of production of acrylamide with the purpose of applying appropriate methods for its purification. Laboratory studies of the purification of an aqueous solution of acrylamide from iron ions were carried out as an element of inhibition of the premature polymerization process.

scholarly journals Low Molecular Weight Gelators Based on Functionalized l-Dopa Promote Organogels Formation

Gels ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 27 ◽  
Author(s):  
Demetra Giuri ◽  
Nicola Zanna ◽  
Claudia Tomasini
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Rheological Properties ◽  
Rhodamine B ◽  
Lauric Acid ◽  
Water Solution ◽  
Preliminary Test ◽  
Low Molecular Weight ◽  
Coupling Reactions ◽  
Low Molecular Weight Gelators

We prepared the small pseudopeptide Lau-l-Dopa(OBn)2-d-Oxd-OBn (Lau = lauric acid; l-Dopa = l-3,4-dihydroxyphenylalanine; d-Oxd = (4R,5S)-4-methyl-5-carboxyl-oxazolidin-2-one; Bn = benzyl) through a number of coupling reactions between lauric acid, protected l-Dopa and d-Oxd with an excellent overall yield. The ability of the product to form supramolecular organogels has been tested with different organic solvents of increasing polarity and compared with the results obtained with the small pseudopeptide Fmoc-l-Dopa(OBn)2-d-Oxd-OBn. The mechanical and rheological properties of the organogels demonstrated solvent-dependent properties, with a storage modulus of 82 kPa for the ethanol organogel. Finally, to have a preliminary test of the organogels’ ability to adsorb pollutants, we treated a sample of the ethanol organogel with an aqueous solution of Rhodamine B (RhB) for 24 h. The water solution slowly lost its pink color, which became trapped in the organogel.

Sign in / Sign up

Export Citation Format

Share Document