Algorithm for the Automated Calculation of the Degree of Substitution of Hydroxyl Groups Modified Polysaccharides for Certification Procedure

2021 ◽  
Author(s):  
Elmaddin Mamedov ◽  
Svetlana Suslova ◽  
Elena Kalmykova
Keyword(s):  
Degree Of Substitution ◽  
Hydroxyl Groups ◽  
Certification Procedure

scholarly journals THE LOCATION OF THE XANTHATE GROUPS IN PARTLY SUBSTITUTED CELLULOSE XANTHATES

1957 ◽  
Vol 35 (12) ◽  
pp. 1522-1533 ◽  
Author(s):  
E. P. Swan ◽  
C. B. Purves
Keyword(s):  
Cellulose Acetate ◽  
Chlorine Dioxide ◽  
Methyl Esters ◽  
Lead Tetraacetate ◽  
Degree Of Substitution ◽  
Hydroxyl Groups ◽  
Primary Position ◽  
Standard Methods ◽  
The Third ◽  
Almost All

Cellulose sodium xanthates of degree of substitution (D.S.) 0.4 to 0.66 were methylated to xanthate S-methyl esters which were then acetylated completely, the final xanthate D.S. remaining close to the original value. Dexanthation with aqueous chlorine dioxide near pH 4.5 and −5° removed almost all of the S-methyl xanthate groups, but the loss of a few acetyl groups from, and the retention of 1 to 2% of sulphur in, the resulting cellulose acetate could not be avoided. The original xanthate groups were presumably represented in this acetate as unsubstituted hydroxyl groups, and these were located by standard methods involving tosylation–iodination, tritylation, and oxidations with lead tetraacetate. Xanthate groups appeared to occupy the third and sixth, but not the second, position in the cellulose, and 53 to 61% of the substituent was in the sixth or primary position; one sample of viscose was "ripened" before the cellulose sodium xanthate was isolated, and the value was 81%. The results were of a preliminary nature, because severe technical difficulties reduced their reliability.

Effect of substitution at C-6 on the susceptibility of pullulan to pullulanases.Enzymatic degradation of modified pullulans

1992 ◽  
Vol 38 (4) ◽  
pp. 324-327 ◽  
Author(s):  
Derek H. Ball ◽  
Bonnie J. Wiley ◽  
Elwyn T. Reese
Keyword(s):  
Key Words ◽  
Uniform Distribution ◽  
Degree Of Substitution ◽  
The Other ◽  
Hydroxyl Groups ◽  
Primary Hydroxyl ◽  
Different Types

Pullulan, with all of the primary hydroxyl groups modified, is an excellent substrate for defining the effect of degree of substitution on biodegradability because of the uniform distribution of substituents on the polysaccharide. 6-Chloro-6-deoxypullulan and 3,6-anhydropullulan are highly resistant to hydrolysis by the four different types of pullulanase. 6-Azido-6-deoxypullulan is resistant to three types but susceptible to hydrolysis by the fourth, isopullulanase.Neopullulanase is strongly inhibited by 6-chloro-6-deoxypullulan and 6-azido-6-deoxypullulan, the other pullulanases much less so. Key words: 3,6-anhydropullulan, 6-azido-6-deoxypullulan, biodegradability, 6-chloro-6-deoxypullulan, pullulan, pullulanases.

scholarly journals MODIFIKASI PATI SECARA ASETILASI DAN APLIKASINYA PADA PEMBENTUKAN FILM

2019 ◽  
Vol 6 (2) ◽  
pp. 100
Author(s):  
Nurhayati Nurhayati
Keyword(s):  
Physicochemical Characteristics ◽  
Degree Of Substitution ◽  
Original Structure ◽  
Hydroxyl Groups ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Native Starch ◽  
Starch Modification ◽  
Modified Starches ◽  
The Media

Along with the development of technology and processing methods used, native starch can be modified to improve its chemical, physicochemical characteristics so that it can be utilized for further products. Modified starches are starches whose hydroxyl groups have been changed by a chemical reaction (esterification, etherification, or oxidation) or by disturbing the original structure. One method of chemical starch modification commonly used is acetylation, which produces acetylated starch. Acetylated starches are produced from starch granules ethered with acetate groups by substituting starch hydroxyl groups. Chemical starch modification by acetylation with inserting an acetyl group in the OH group starch through the acetylation reaction. The reagents commonly used in the acetylation method are vinyl acetate, acetic acid, and acetic anhydrous. Acetylated starch has the physicochemical properties advantages such as gelatinization temperature, development power, solubility, and paste clarity are high. Another advantage is better storage and cooking stability when compared to native starch. In addition, the quality of the products produced from starch acetate is more stable and resistant to retrogradation. In general, starch modification by acetylation is greatly influenced by several factors, including intrinsic and extrinsic factors. Intrinsic factors include the structure of the granules (the shape and size of the granules), the composition of the granules (ratio of amylopectin and amylose, and compositions other than starch). While extrinsic factors consist of reagents (reagent type, concentration), condition of the media reaction (temperature, pH, reaction time, and pressure ), these factors will affect the degree of substitution,% acetyl, physicochemical, morphological and rheological properties, thermal and pasting of acetylated starch. In its application based on the degree of substitution, acetylated starch is classified into three levels, namely low, medium, high. Acetate starch with low DS (0.01-0.2) can function as film-forming, binder, adhesive, thickener, stabilizer, and texturing agent.

scholarly journals Novel polymer surfactants based on the branched silatrane-containing polyesters and polyethers

2019 ◽  
Vol 14 (5) ◽  
pp. 61-70 ◽  
Author(s):  
V. V. Istratov ◽  
V. I. Gomzyak ◽  
O. V. Yamskova ◽  
G. D. Markova ◽  
L. G. Komarova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Degree Of Substitution ◽  
Biologically Active ◽  
Hydroxyl Groups ◽  
Critical Micelle Concentrations ◽  
Surface Active Properties ◽  
Hydrophilic Lipophilic Balance ◽  
Surface Active ◽  
The Stability ◽  
Polymer Surfactants

Objectives. Biologically active polymeric surfactants are a new promising class of macromolecules that can find application in medicine, cosmetology, and agriculture. In this study, a number of new biologically active amphiphilic polymers based on branched silatrane-containing polyesters and polyethers were obtained, and their surface-active properties were investigated.Methods. The branched polymers were represented by polyethers and polyesters, obtained respectively via the anionic polymerization of 1,2-epoxypropanol or a combination of equilibrium polycondensation and ring opening polymerization. The polymers were modified with 3-isocyanopropylsilatrane and trimethylethoxysilane to obtain the amphiphilic compounds containing silatrane groups bonded to the polymer backbone by the urethane bond. The structure of the synthesized polymer silatranes was confirmed via nuclear magnetic resonance spectroscopy and gel permeation chromatography. The surface active properties of all the copolymers obtained were investigated in connection with their obvious amphiphilicity. In particular, the formation of micelles in aqueous solutions is such a property. The critical micelle concentrations were determined by a method of quenching the fluorescence of the polymers.Results. It was shown that the values of the critical micelle concentrations and the hydrophilic-lipophilic balance values of polymers determined by the Griffin equation correlate well with each other. A linear relationship between the hydrophilic-lipophilic balance and the critical micelle concentrations was established. At the same time, polyether-based polymers generally showed higher critical micelle concentrations than polyester-based polymers, although the hydrophilic-lipophilic balance values for polymers of different series, but with close degrees of substitution, were close. It was found that the use of all synthesized polymers as stabilizers of direct and reverse emulsions leads to an increase in the aggregative stability of both types of emulsions. The stability of emulsions depended both on the degree of substitution of peripheral hydroxyl groups of polymers by silatranes and on the molecular weight and structure of the branched block of polymers. The stability of direct emulsions increased for all polymers, while that of inverse emulsions decreased with an increasing degree of substitution of hydroxyl groups by silatranes. The increase of the branched block molecular weight led to an increase of droplet sizes for both direct and inverse emulsions. The smallest droplet size for direct and inverse emulsions was obtained using polymers with low molecular weight branched polyester blocks as surfactants.Conclusions. The results obtained prove the possibility of creating polymer surfactants containing silatrane groups. By varying the structure of the polymer, its molecular weight and the degree of substitution of peripheral functional groups, it is possible to obtain surfactants with desired surface properties.

HES 200/0.5 Is not HES 200/0.5

1995 ◽  
Vol 74 (06) ◽  
pp. 1452-1456 ◽  
Author(s):  
Johannes Treib ◽  
Anton Haass ◽  
Gerhard Pindur ◽  
Ulrich T Seyfert ◽  
Wolfgang Treib ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydroxyethyl Starch ◽  
Clinical Relevance ◽  
Dilution Effect ◽  
Repeated Administration ◽  
Plasma Viscosity ◽  
Degree Of Substitution ◽  
Pronounced Increase ◽  
Large Molecules ◽  
Mean Molecular Weight

SummaryThe plasma clearance of hydroxyethyl starch (HES) depends on the initial molecular weight and the degree of substitution. So far, little attention has been paid to the clinical relevance of the C2/C6 substitution ratio of hydroxyethyl starch.10 patients with cerebrovascular circulatory disturbance received hemodilution therapy for 10 days, consisting of 10% HES 200/0.5 (mean molecular weight 200 kD, degree of substitution 0.5) with a C2/C6 ratio of 13.4. A second group of 10 patients received a starch solution with identical initial molecular weight and degree of substitution but with a C2/C6 ratio of 5.7.After the administration of a single dose, no significant differences between the two groups were observed. After repeated administration, significant differences could be detected in hemorheology, coagulation and elimination (p<0.01). The larger C2/C6 ratio led to a higher intravascular mean molecular weight (95 vs. 84 kD), which in turn led to a higher increase in serum concentration during the therapy (14.7 vs.8.6 mg/ml). Hematocrit was lowered more (-30,5 vs. -23,5%) and plasma viscosity was increased more. There was also a more pronounced increase in partial thromboplastin time (+30% vs. +13%) and a factor of 2 larger decrease of factor VIII/von Willebrand factor-complex (p <0.01), which exceeded the dilution effect.The higher C2/C6 ratio of HES 200/0.5/13.4 slows down enzymatic degradation. After repeated administration of this starch, large molecules accumulate which are inefficiently degraded. The same effect has been observed after therapy with highly-substituted HES. This accumulation of large molecules leads to a beneficial longer lasting volume effect. The disadvantages include an increase in plasma viscosity and coagulation disturbances, which cannot be explained with the respective dilution effect alone. For these reasons, the C2/C6 ratio is of clinical relevance and should be included in the product labeling in the future.

Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL
Keyword(s):  
Carbon Content ◽  
Acid Hydrolysis ◽  
13C Nmr ◽  
Kraft Lignin ◽  
Kappa Number ◽  
Hydroxyl Groups ◽  
Kraft Pulps ◽  
Quaternary Carbon ◽  
Oxygen Delignification

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.

Synthesis and antimicrobial properties of oligomeric silsesquioxanes containing quaternized nitrogen atoms and hydroxyl groups in organic shell

2017 ◽  
Vol 39 (3) ◽  
pp. 188-194
Author(s):  
M.A. Gumenna ◽  
◽  
N.S. Klimenko ◽  
A.V. Stryutsky ◽  
D.M. Hodyna ◽  
...  
Keyword(s):  
Antimicrobial Properties ◽  
Hydroxyl Groups ◽  
Organic Shell

QM/MM Simulations of Organic Phosphorus Adsorption at the Diaspore-Water Interface

2019 ◽  
Author(s):  
Prasanth Babu Ganta ◽  
Oliver Kühn ◽  
Ashour Ahmed
Keyword(s):  
Interaction Energy ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mineral Surfaces ◽  
Soil Mineral ◽  
Phosphorus Adsorption ◽  
Covalent Bonds ◽  
Binding Mechanisms

The phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. Related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphate onto Fe-oxide surfaces. But a molecular-level understanding for the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentate for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

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