A theoretical and experimental study on etherification of primary alcohols with the hydroxyl groups of cellulose chain (n=1-3) in acidic condition

2021 ◽  
pp. 130314
Author(s):  
Dang T. Nguyen ◽  
Quan T. Pham
Keyword(s):  
Experimental Study ◽  
Acidic Condition ◽  
Hydroxyl Groups ◽  
Primary Alcohols ◽  
Cellulose Chain

scholarly journals A Theoretical and Experimental Study on Esterification of Citric Acid with the Primary Alcohols and the Hydroxyl Groups of Cellulose Chain (n = 1-2) in Parched Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Dang T. Nguyen ◽  
Quan T. Pham
Keyword(s):  
Citric Acid ◽  
Ring Opening ◽  
Density Functional ◽  
Membered Ring ◽  
Hydroxyl Groups ◽  
Dehydration Reaction ◽  
Primary Alcohols ◽  
Reaction Step ◽  
Cellulose Chain ◽  
Ring Opening Reaction

Esterification of citric acid (CA) with the primary alcohols and the hydroxyl groups of cellulose chain (n = 1-2) in parched condition were investigated by using density functional theory (DFT) method and a two-layer ONIOM approach. Geometry and energy of reactants, products, and transition state (TS) structures were optimized at B3LYP/6-311g (d, p) level and ONIOM (B3LYP/6-311g (d, p):PM3MM) level. The computational results show that the esterification occurs in the two main steps: the first step is the dehydration reaction of CA to form anhydrides of 5-membered ring and 6-membered ring and the second step is the ring opening reaction with the hydroxyl –OH groups to form the ester products. The energy barrier of dehydration reaction step is much higher than that of ring opening reaction step. Effect of substituent R in primary alcohol R-CH2OH (R: CH=CH2, CH2NHCH3, CH2OCH3, CH2Cl) and cellulose chain (1G, 2G) on the reactivity, which has negative inductive effect –I, is significant. The combination of calculation data and experiment data were applied to make findings more rigorous. The activation energy of CA was determined by using differential scanning calorimetry (DSC) and thermal gravimetric (TG) analysis to be E a exp  = 47.8 kcal/mol; the experimental data favoured the dehydration reaction step of CA.

H2 formation on Mg-rich amorphous silicates

2019 ◽  
Vol 15 (S350) ◽  
pp. 109-113
Author(s):  
Vito Mennella ◽  
Tushar Suhasaria
Keyword(s):  
Experimental Study ◽  
Infrared Spectroscopy ◽  
Formation Process ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Photodissociation Regions ◽  
H2 Formation

AbstractWe present the results of an experimental study on the interaction of D atoms with Mg-rich amorphous silicates. The effects of D irradiation have been analyzed by infrared spectroscopy. The results indicate that HD forms by abstraction of hydrogen atoms chemisorbed in the hydroxyl groups of silicate grains. The formation process occurs for grain and atom temperatures relevant to photodissociation regions.

Chemoselective Electrochemical Oxidation of Secondary Alcohols using a Recyclable Chloride-Based Mediator

Synlett ◽  
2021 ◽  
Author(s):  
Florian Sommer ◽  
Oliver Kappe ◽  
David Cantillo
Keyword(s):  
Nitroxyl Radical ◽  
Supporting Electrolyte ◽  
Extraction Procedure ◽  
Hydroxyl Groups ◽  
Chloride Salt ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Oxidation Of Alcohols ◽  
Simple Extraction ◽  
Unsolved Issue

Selective anodic oxidation of alcohols in the presence of other functional groups can be accomplished using nitroxyl radical mediators. However, the electrochemical chemoselective oxidation of secondary alcohols in the presence of primary alcohols is an unsolved issue. Herein, we report an electrochemical procedure for the selective oxidation of secondary alcohols using an inexpensive chloride salt that acts as redox mediator and supporting electrolyte. The method is based on the controlled anodic generation of active chlorine species, which selectively oxidize secondary alcohols to the corresponding ketones when primary hydroxyl groups are present. The method has been demonstrated for a variety of substrates. The corresponding ketones were obtained in good to excellent yields. Moreover, the chloride salt can be easily recovered and reutilized by a simple extraction procedure, rendering the method highly sustainable

scholarly journals Role of Hydroxyl Groups in the Basic Reactivity of MgO: a Theoretical and Experimental Study

2006 ◽  
Vol 61 (4) ◽  
pp. 479-488 ◽  
Author(s):  
C. Chizallet ◽  
G. Costentin ◽  
H. Lauron-Pernot ◽  
J. M. Krafft ◽  
P. Bazin ◽  
...  
Keyword(s):  
Experimental Study ◽  
Hydroxyl Groups

scholarly journals Enhancement of the Interlayer Interaction between Polystyrene and Polyvinyl Alcohol by Ozone Treatment

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Lin Su ◽  
Jie Li ◽  
Jing Li ◽  
Qiaomei Chu ◽  
Bo Li ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Inertial Confinement Fusion ◽  
Interfacial Adhesion ◽  
Room Temperature ◽  
Interfacial Interaction ◽  
Acidic Condition ◽  
Ozone Treatment ◽  
Hydroxyl Groups ◽  
Inertial Confinement ◽  
Confinement Fusion

The ozonization modification of polystyrene (PS) was conducted in acidic condition to enhance the interfacial interaction between PS and polyvinyl alcohol (PVA). Infrared spectra results revealed that the carbonyl and hydroxyl groups were successfully introduced to the PS film by ozonization. The hydrophobic PS was turned to be hydrophilic to some extent by contact angle experiment, which led to the enhancement of interfacial adhesion between PS and PVA. In addition, the adsorption of PS to PVA was also improved. Nano indenter measurement indicated the interfacial interaction between PS film and PVA film was obviously enhanced by 40% after ozonization at room temperature for 2 h in acidic condition, which will benefit for fabricating laser inertial confinement fusion container.

The Dielectric Properties of Crystalline Long-Chain n-Primary Alcohols at Low Frequencies

1951 ◽  
Vol 4 (3) ◽  
pp. 365
Author(s):  
RJ Meakins ◽  
JW Mulley
Keyword(s):  
Dielectric Properties ◽  
Primary Alcohol ◽  
Dielectric Constants ◽  
Double Layers ◽  
Significant Feature ◽  
Hydroxyl Groups ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Dielectric Absorption ◽  
Long Chain

In a previous paper it was reported that certain crystalline forms of long-chain secondary alcohols show abnormally large dielectric absorption and dispersion of the dielectric constant at audio and radio frequencies. The present paper describes an extension of the investigation to n-primary alcohols and discusses the results in terms of the previously suggested theory of dielectric absorption due to the presence of hydrogen-bonded chains of hydroxyl groups. The most significant feature of the results is that the absorption is larger and occurs at much lower frequencies than for the secondary alcohols. This is considered to be due to the end-to-end arrangement of the molecules in n-primary alcohol crystals, which gives double layers of hydroxyl groups and enables the formation of more extensive hydrogen-bond chains. The dielectric constants at the lowest frequencies are almost as large as those previously reported by Hoffmann and Smyth (1949) for the " waxy " forms of n-primary alcohols. Further aspects described are the changes in dielectric properties during storage, the differences between the melted and recrystallized forms, and the effect of dispersing the molecules in an inert solid solvent. In each of these aspects the observed behaviour is similar to that previously reported for the secondary alcohols.

USING NANO-TiO2 AS CO-CATALYST FOR IMPROVING WRINKLE-RESISTANCE OF COTTON FABRIC

2007 ◽  
Vol 14 (04) ◽  
pp. 571-575 ◽  
Author(s):  
C. W. M. YUEN ◽  
S. K. A. KU ◽  
C. W. KAN ◽  
Y. F. CHENG ◽  
P. S. R. CHOI ◽  
...  
Keyword(s):  
Inorganic Phosphorus ◽  
Phosphorus Compounds ◽  
Hydroxyl Groups ◽  
Cellulose Chain ◽  
Nano Tio2 ◽  
Co Catalyst ◽  
Wrinkle Resistance ◽  
Phosphorus Containing ◽  
Fabric Strength ◽  
Ethylene Urea

In order to prevent cotton wrinkling, hydroxyl groups in the cellulose chain of cotton are partially crosslinked to keep the chain fixed relative to each other with dimethylol dihydroxy ethylene urea (DMDHEU). However, DMDHEU suffers disadvantages of reduced fabric strength and releasing of free formaldehyde. Recently, 1,2,3,4-butane tetracarboxylic acid (BTCA) has been explored as a new wrinkle-resistant agent providing similar performance to that of DMDHEU. In BTCA finishing, catalyst of inorganic phosphorus-containing acids was used but such phosphorus compounds have an adverse impact on the environment. In this paper, nano- TiO 2 was used as a co-catalyst with sodium hypophophite in the treatment of cotton with BTCA, and the final properties were assessed.

Theoretical Study of the Oxidation Mechanism of Hematoxylin in Aqueous Solution

2012 ◽  
Vol 65 (5) ◽  
pp. 486 ◽  
Author(s):  
Mansoor Namazian ◽  
Hamid R. Zare ◽  
Michelle L. Coote
Keyword(s):  
Aqueous Solution ◽  
Experimental Study ◽  
Electrochemical Oxidation ◽  
Chemical Reaction ◽  
Oxidation Mechanism ◽  
Oxidation Potential ◽  
Hydroxyl Groups ◽  
Standard Hydrogen Electrode ◽  
Hydrogen Electrode ◽  
Irreversible Chemical Reaction

The oxidation of the two catechol rings A and B in the chemical structure of hematoxylin in aqueous solution has been studied theoretically in order to identify the mechanism of oxidation. In a recent experimental study, the oxidation mechanism of hematoxylin was designated an ErCiEr process in which an irreversible chemical reaction (Ci) followed the reversible chemical electrochemical oxidation (Er) of the catechol unit connected to the six-membered ring of the molecule (ring A). The theoretical results presented herein indicate that the electrochemical oxidation of ring B is actually slightly more favoured than ring A, although the potential separation is so small that they were unable to be distinguished in the experimental study. We therefore suggest that the most likely mechanism is ErErCiEr, in which two reversible electrochemical oxidation reactions (Er) occur preceding the irreversible chemical reaction (Ci), though we cannot rule out a contribution from ErCiEr. The calculated oxidation potential (0.719 V v. standard hydrogen electrode) is in close accord with the experimental value (0.759 V v. standard hydrogen electrode). The deprotonation of five hydroxyl groups of hematoxylin in aqueous solution is also studied and the order of acidic strength of these groups has been identified.

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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