scholarly journals Analysis on Impact of Acid Hydrolysis on the Hydrogen Bonding Network in Cellulose to Obtain Microcrystalline Cellulose: A Statistical Approach

2021 ◽  
Author(s):  
Vishnu Prabha Muthusamy ◽  
Vaideki Krishnakumar
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Acid Hydrolysis ◽  
Microcrystalline Cellulose ◽  
Cellulose Microfibrils ◽  
Degree Of Crystallinity ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrogen Bonding Network ◽  
Hydrolysis Of

Abstract Hydrolysis of a cellulose biomass results in breaking down the cellulose microfibrils into microcrystalline cellulose (MCC) or nanocrystalline cellulose (NCC) depending on the reaction conditions. Cellulose microfibrils are established robustly due to the synergistic interaction of van der Waals, inter- and intra-molecular hydrogen bonds and glycosidic bond between glucan moieties of cellulose polysaccharide. The hydrogen bonding network plays a crucial role in conforming cellulose chains into crystalline and amorphous region thereby determining its degree of crystallinity. The knowledge of hydrogen bonds in cellulose hence becomes indispensable to understand the crystallinity of cellulose before and after a hydrolysis reaction. However, the nature of hydrogen bonds after hydrolysis and how they contribute to the mechanical properties of resultant MCC/NCC are yet to be realized. This paper is therefore intended to discuss the degree of crystallinity of cellulose particles obtained after hydrolyzing waste cotton fibers (WCF) in two parts: part I, obtaining MCC with maximum total crystallinity index (TCI) by acid hydrolysis of WCF using Box Behnken Design; part II, comparing degree of crystallinity of MCC sample exhibiting highest TCI with that of WCF using analytical tools like X-ray Photoelectron Spectrometer, X-ray Diffractometer and Fourier Transform Infra- Red spectrometer. The physical dimension of MCC particle with maximum TCI has been verified using Field Emission Scanning Electron Microscopic images.

Improved Enzymatic Depolymerization of Chitosan by Ionic Liquid Pretreatment and the Effect of Oligo-Chitosan on Intestinal Flora In Vitro

2011 ◽  
Vol 391-392 ◽  
pp. 1319-1323
Author(s):  
Cui Zheng ◽  
Lin Li ◽  
Hao Pang ◽  
Zhao Mei Wang ◽  
Na Li
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonds ◽  
Molecular Hydrogen ◽  
Intestinal Flora ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
Positive Effect ◽  
Enzymatic Depolymerization

It still remains challenging for effective hydrolysis of chitosan into chitosan oligomers. In this work, a pretreatment was conducted on chitosan by an ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), aiming at improving enzymatic depolymerization of chitosan. X-ray diffraction analysis indicated that the inter- and intra-molecular hydrogen bonds within chitosan molecules were broken by [C4mim]Cl and the crystalline was destroyed. The oligo-chitosan hydrolyzed from IL-pretreated chitosan, coded as COS-IL, showed a DP of 3~5, in contrast to DP 5~8 with oligo-chitosan obtained from untreated chitosan(coded as COS-UN). COS-IL was more effective than COS-UN in inhibiting intestinal spoilage bacterials growth and it has positive effect on the growth of intestinal probiotic bacterials.

On the Origin of the Red Color of Aqueous-Solutions of 2,3-Dichloro-5,6-Dicyano-1,4-Benzoquinone (ddq). Crystal Structure of the Ammonium Salt of 2-Cyano-5,6-Dichloro-3-Hydroxy-1,4-Benzoquinone

1987 ◽  
Vol 40 (3) ◽  
pp. 625 ◽  
Author(s):  
HD Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Single Crystal ◽  
Ammonium Salt ◽  
Structure Determination ◽  
Aqueous Ethanol ◽  
X Ray ◽  
Red Color ◽  
Hydrolysis Of

Hydrolysis of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in aqueous ethanol gives the deep-red coloured ammonium salt of a monocyano-dichloro-monohydroxy-benzoquinone which crystallizes in the tetragonal space group I41 /a, a 20.832(5), c 8.618(2) �, Z 16. Single-crystal X-ray structure determination (R 0.036 for 1185 'observed' reflections) show the presence of ammonium cations forming hydrogen bonds in the lattice alternatingly with the tautomeric anion of 2-cyano-5,6-dichloro-3-hydroxy-1,4-benzoquinone and 3-cyano-5,6-dichloro-4-hydroxy-1,2-benzoquinone.

A 16-connected three-dimensional hydrogen-bonding network in tetrakis(4-aminopyridinium) perylene-3,4,9,10-tetracarboxylate octahydrate

2014 ◽  
Vol 70 (7) ◽  
pp. 668-671 ◽  
Author(s):  
Zhi-Hui Zhang ◽  
Jin-Long Wang ◽  
Ning Gao ◽  
Ming-Yang He
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Linear Chain ◽  
Three Dimensional ◽  
Organic Salt ◽  
Water Molecules ◽  
The Novel ◽  
One Dimensional ◽  
Connected Node ◽  
Hydrogen Bonding Network

The novel title organic salt, 4C5H7N2+·C24H8O84−·8H2O, was obtained from the reaction of perylene-3,4,9,10-tetracarboxylic acid (H4ptca) with 4-aminopyridine (4-ap). The asymmetric unit contains half a perylene-3,4,9,10-tetracarboxylate (ptca4−) anion with twofold symmetry, two 4-aminopyridinium (4-Hap+) cations and four water molecules. Strong N—H...O hydrogen bonds connect each ptca4−anion with four 4-Hap+cations to form a one-dimensional linear chain along the [010] direction, decorated by additional 4-Hap+cations attached by weak N—H...O hydrogen bonds to the ptca4−anions. Intermolecular O—H...O interactions of water molecules with ptca4−and 4-Hap+ions complete the three-dimensional hydrogen-bonding network. From the viewpoint of topology, each ptca4−anion acts as a 16-connected node by hydrogen bonding to six 4-Hap+cations and ten water molecules to yield a highly connected hydrogen-bonding framework. π–π interactions between 4-Hap+cations, and between 4-Hap+cations and ptca4−anions, further stabilize the three-dimensional hydrogen-bonding network.

Structure Elucidation of 2-Amino-5-phenyl-2-oxazolin-4-one (Pemoline) and X-Ray Structure of its Hydrolysis Product 5-Phenyl-oxazolidine-2,4- dione

2005 ◽  
Vol 60 (8) ◽  
pp. 853-857 ◽  
Author(s):  
Piotr Kuś ◽  
Peter G. Jones ◽  
Rafał Celiński
Keyword(s):  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Acid Hydrolysis ◽  
Single Crystals ◽  
Structure Elucidation ◽  
Hydrolysis Product ◽  
Spectroscopic Properties ◽  
Aqueous Acetic Acid ◽  
X Ray ◽  
Independent Molecules

In this study we compare spectroscopic properties of pemoline (2-amino-5-phenyl-2-oxazolin- 4-one) and its acid hydrolysis product 5-phenyl-oxazolidine-2,4-dione. Crystallization of pemoline from aqueous acetic acid gave single crystals of compound 2, the structure of which was determined by X-ray studies. All four crystallographically independent molecules form dimers linked by N-H···O = C hydrogen bonds.

scholarly journals Crystal structure of pentakis(ethylenediamine-κ2N,N′)lanthanum(III) trichloride–ethylenediamine–dichloromethane (1/1/1)

2014 ◽  
Vol 70 (11) ◽  
pp. 424-426 ◽  
Author(s):  
Hope T. Sartain ◽  
Richard J. Staples ◽  
Shannon M. Biros
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Bypass Procedure ◽  
Hydrogen Bonding Network ◽  
Additional Hydrogen

We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethylenediamine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethylenediamine molecule and three Cl−anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl−anions and the NH groups on the metal-bound ethylenediamine ligands. The free ethylenediamine molecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered molecule of dichloromethane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990).Acta Cryst.A46, 194–201].

Polysulfonylamine, CXVII Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Sechs systematisch variierte sek.-Ammonium-dimesylamide mit sechs verschiedenen null-, ein-oder zweidimensionalen Wasserstoffbrückenmustern/ Polysulfonylamines, CXVII Hydrogen Bonding in Crystalline Onium Dimesylamides: Six Systematically Varied sec. - Ammonium Dimesylamides Exhibiting Six Different Zero-, One-, or Two-Dimensional Hydrogen Bonding Patterns

1999 ◽  
Vol 54 (11) ◽  
pp. 1420-1430 ◽  
Author(s):  
Oliver Moers ◽  
Karna Wijaya ◽  
Dagmar Henschel ◽  
Armand Blaschette ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Ionic Crystals ◽  
Molecular Fragments ◽  
Triclinic Space Group ◽  
X Ray ◽  
Rigid Conformation ◽  
Morpholinium Salt ◽  
Crystal Packings

In order to examine packing preferences and hydrogen bond patterns in secondary ammonium salts, low-temperature X-ray analyses were conducted for six compounds of general formula R2NH2+MeSO2)2 N-, where R2NH2+ = Me2NH2+ (1, triclinic, space group P1̄̄), MeEtNH2+,(2, monoclinic, P21/c), Et2NH2+ (3. triclinic, P1), pyrrolidinium (4, triclinic, P1), piperidinium (5, monoclinic, C2/c) or morpholinium (6, monoclinic, P21/c). Throughout the series, the constant anion retains a rigid conformation approximating to C2 symmetry and thus provides a geometrically reliable set of five potential hydrogen bond acceptors. Nevertheless, the six compounds exhibit a variety of unpredictable packing patterns, showing that, in unfavourable cases, the steric demands of molecular fragments not involved in hydrogen bonding can substantially alter the structure of a family of ionic crystals. In the present structures, the NH2+ donor groups form hydrogen bonds N+-H···N-/O to two (3-6) or three (1,2) adjacent anions. The occurrence of various two-, three- and four-centre hydrogen bonds leads to six different patterns, resulting in cation-anion layers (1, 2), discrete formula unit dimers (3, 4) or cation-anion chains (5, 6); in the morpholinium salt 6, these chains are associated into layers by a weak N+ - H ··· O(cation) interaction. In each of the crystal packings, short C-H···O contacts with H···O ≤ 270 pm and C-H ···O ≥ 130° are observed.

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