scholarly journals Partitioning of Molecular Weight - An Elliptic Model for Isomers

2021 ◽  
pp. 239-247
Author(s):  
Lemi Türker
Keyword(s):  
Molecular Weight ◽  
Regression Model ◽  
Real Number ◽  
Optically Active ◽  
Elliptic Model

Partitioning of any real number has been achieved based on an elliptic model introduced. Then, it has been adopted to isomeric molecules including optically active ones. Certain angles and bounds are defined. A bivariant regression model has been proposed for a set of isomeric molecules and discussed.

Synthesis of New Phosphazene High Molecular Weight Polymers Containing Functionalized and Optically Active Spirocyclic Groups

1998 ◽  
Vol 31 (10) ◽  
pp. 3189-3196 ◽  
Author(s):  
Gabino A. Carriedo ◽  
Francisco J. García Alonso ◽  
Pedro A. González ◽  
José L. García-Alvarez
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Optically Active ◽  
High Molecular Weight Polymers

Recent Studies on the Application of Enzymes in the Synthesis of Polyesters

1990 ◽  
Vol 218 ◽  
Author(s):  
Cary J. Morrow ◽  
Eugenia M. Brazwell ◽  
Dianela Filos ◽  
Juanita Mercure ◽  
Rosemary Romero ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ambient Temperature ◽  
Organic Solvents ◽  
Pancreatic Lipase ◽  
Bound Water ◽  
Optically Active ◽  
Porcine Pancreatic Lipase ◽  
Dibenzyl Ether ◽  
High Boiling Solvent ◽  
Hydrolysis Of

AbstractEnzyme-catalyzed preparation of polymers offers several potentially valuable advantages over the usual polymerization procedures. This paper summarizes our successful use of lipase-catalyzed polycondensations to prepare both a series of achiral [AA-BB]x polyesters from bis(2,2,2- trichloroethyl) alkanedioates and diols and of an optically active, epoxy-substituted polyester having a stereochemical purity estimated to be greater than 96%, from racemic bis(2,2,2-trichloroethyl) trans-3,4-epoxyhexanedioate and 1,4-butanediol. All of the reactions were carried out at ambient temperature in anhydrous, low to intermediate polarity, organic solvents such as ether, THF, 2-ethoxyethyl ether, dibenzyl ether, o-dichlorobenzene, or methylene choride, using porcine pancreatic lipase (PPL) as the catalyst. The molecular weight achieved by the polycondensation is limited by accumulation of the trihaloethanol that forms as the reaction progresses, probably because it frees enzyme-bound water permitting hydrolysis of the polymer to occur. This problem has been alleviated by using a high boiling solvent and removing the alcohol by placing the re'action mixture under vacuum.

Chemical synthesis of novel biodegradable polyesters

1995 ◽  
Vol 41 (13) ◽  
pp. 282-288 ◽  
Author(s):  
Y. Hori ◽  
Y. Takahashi ◽  
A. Yamaguchi ◽  
T. Hagiwara
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Lactone Ring ◽  
Ring Opening Polymerization ◽  
Optically Active ◽  
Bond Breaking ◽  
Carbonyl Carbon ◽  
Biodegradable Polyesters ◽  
Molecular Weights ◽  
High Molecular Weight Poly

Distannoxane complexes catalyze the ring-opening polymerization of optically active β-butyrolactone (β-BL) to afford a high molecular weight poly(3-hydroxybutyrate). When 1-ethoxy-3-chlorotetrabutyldistannoxane was used as a catalyst (catalyst/(R)-β-BL = 1/8000 at 100 °C for 4 h), poly((R)-3-hydroxybutyrate) was obtained from (R)-β-BL in a yield of 99%. The copolymerizations of (R)-β-BL with racemic β-BL in several ratios gave corresponding stereocopolymers. The copolymerizations of (R)-β-BL with ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, and L-lactide afforded novel optically active and biodegradable polyesters of high molecular weights, comprising (R)-3-hydroxybutyrate (3HB). The polymerization of (R)-β-BL catalyzed by the distannoxane complexes proceeded by bond breaking between the carbonyl carbon and oxygen atom of the lactone ring (acyl cleavage) with retention of the configuration and little or no racemization. Polymers that have over 80 mol% of the (R)-3HB unit were found to have almost the same degree of biodegradability as the copolyester of 3-hydroxybutyrate and 11% 3-hydroxyvalerate produced by the microbial method.Key words: distannoxane, ring-opening polymerization, poly(3-hydroxybutyrate), poly(3-hydroxyalkanoates), biodegradable polymer.

Simple process for preparation of optically active methacrylates polymer with controlled molecular weight

2011 ◽  
Vol 68 (6) ◽  
pp. 1525-1535
Author(s):  
Xing Juan Chen ◽  
Min Zhao ◽  
Shan Shan Gu
Keyword(s):  
Molecular Weight ◽  
Optically Active ◽  
Simple Process

scholarly journals Poly[(N-acryloyl glycinamide)-co-(N-acryloyl l-alaninamide)] and Their Ability to Form Thermo-Responsive Hydrogels for Sustained Drug Delivery

Gels ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 13 ◽  
Author(s):  
Mahfoud Boustta ◽  
Michel Vert
Keyword(s):  
Molecular Weight ◽  
Methylene Blue ◽  
Transition Temperature ◽  
Average Molecular Weight ◽  
Optically Active ◽  
Sustained Drug Delivery ◽  
Gel Consistency ◽  
Reversible Gel ◽  
Responsive Hydrogels

In the presence of water, poly(N-acryloyl glycinamide) homopolymers form highly swollen hydrogels that undergo fast and reversible gel↔sol transitions on heating. According to the literature, the transition temperature depends on concentration and average molecular weight, and in the case of copolymers, composition and hydrophilic/hydrophobic character. In this article, we wish to introduce new copolymers made by free radical polymerization of mixtures of N-acryloyl glycinamide and of its analog optically active N-acryloyl l-alaninamide in various proportions. The N-acryloyl l-alaninamide monomer was selected in attempts to introduce hydrophobicity and chirality in addition to thermo-responsiveness of the Upper Critical Solubilization Temperature-type. The characterization of the resulting copolymers included solubility in solvents, dynamic viscosity in solution, Fourrier Transform Infrared, Nuclear Magnetic Resonance, and Circular Dichroism spectra. Gel→sol transition temperatures were determined in phosphate buffer (pH = 7.4, isotonic to 320 mOsm/dm3). The release characteristics of hydrophilic Methylene Blue and hydrophobic Risperidone entrapped in poly(N-acryloyl glycinamide) and in two copolymers containing 50 and 75% of alanine-based units, respectively, were compared. It was found that increasing the content in N-acryloyl-alaninamide-based units increased the gel→sol transition temperature, decreased the gel consistency, and increased the release rate of Risperidone, but not that of Methylene Blue, with respect to homo poly(N-acryloyl glycinamide). The increase observed in the case of Risperidone appeared to be related to the hydrophobicity generated by alanine residues.

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