Reactivity of Microcrystalline Cellulose with Methyltrimethoxysilane and 3-(2-Aminoethylamino) propyltrimethoxysilanes

In the presented research, two trialkoxysilanes were used to investigate their reactivity with microcrystalline cellulose (MCC) applied as a model material. As a continuation of the previous study, the research aimed at evaluation of the durability and potential reversibility of the silane treatment. Two different solvents and a mixture thereof were used for cellulose modification. The influence of amino group/pH, an excess of silanes and re-soaking with water on binding with cellulose was examined. The results obtained confirm that both selected silanes can effectively modify MCC. However, the treatment with 3-(2-aminoethylamino)propyltrimethoxysilane occurred more effective than with Methyltrimethoxysilane due to the presence of amino groups. Among the three tested solvents, the most effective was pure water. In contrast, the use of ethanol and a mixture of ethanol and water gave significantly worse results. Summarising, the presented research clearly shows how important the type of the functional group in alkoxysilanes is for its chemical reactivity with natural polymers, which is crucial for their application in waterlogged wood conservation.

Download Full-text

Phosphoryl to carbonyl migration of amino groups in mixed anhydrides

Canadian Journal of Chemistry ◽

10.1139/v86-280 ◽

1986 ◽

Vol 64 (9) ◽

pp. 1702-1708 ◽

Cited By ~ 9

Author(s):

Jill Symes ◽

Tomasz A. Modro

Keyword(s):

Transition State ◽

Lewis Acids ◽

Reaction Rate ◽

Functional Group ◽

Substituent Effects ◽

Activation Parameters ◽

Amino Group ◽

Amino Groups ◽

Group Transfer ◽

Mixed Anhydrides

Mixed anhydrides derived from carboxylic and amidophosphoric acids, (RO)(R′2N)P(O)OC(O)R″ (1), undergo unimolecular fragmentation yielding carboxyamides, R″C(O)NR′2, and metaphosphate esters, ROPO2. The mechanism of the amino group transfer was studied for substrate 1a (1, R = R′ = Me; R″ = Ph); solvent as well as substituent effects indicate little (if any) charge development in the transition state. The effects of solvents and Lewis acids on the reaction rate and the activation parameters determined for 1a can be explained best in terms of stabilizing interactions with either carboxyamide or metaphosphate being formed in the course of reaction. The transfer of a functional group from one acyl center to another was investigated for other anhydride systems and the relative contributions of the fragmentation vs. disproportionation of substrates are discussed.

Download Full-text

CHITOSAN-BASE COAGULANTS IN COAGULATION-FLOCCULATION OF KAOLIN SUSPENSION

JURNAL KIMIA MULAWARMAN ◽

10.30872/jkm.v16i1.668 ◽

2019 ◽

Vol 16 (1) ◽

pp. 16

Author(s):

Bambang Piluharto ◽

Mufrihah Nurhayati ◽

Asnawati Asnawati

Keyword(s):

Molecular Weight ◽

Functional Group ◽

Group Analysis ◽

Natural Polymers ◽

Amino Groups ◽

Environment Friendly ◽

Kaolin Suspension ◽

Functional Group Analysis ◽

Water Treatments ◽

Different Molecular Weight

Coagulation-flocculation is one of the waste water treatments using coagulant/flocculants agent. Using coagulant/flocculants based on natural polymers were many used due to many available, renewable source, and environment friendly. One of that coagulant/flocculants was chitosan that can be produced through deacetylation of chitin. Amino groups in the chitosan structure play important role in the coagulant/flocculants process. The aim of research is using chitosan-based coagulants in the coagulation-flocculation of kaolin suspension. In here, there were two coagulants type, first, single coagulant which chitosan with different molecular weight added alone in kaolin suspension. Second, mix coagulants which chitosan aid with alum in kaolin suspension. As the result, functional group analysis showed that chitosan with different molecular weight have the same functional groups. Increasing molecular weight of chitosan increase NH2 groups and degree of deacetylation. The removing turbidity of kaolin suspension showed that increasing molecular weight chitosan increase removing turbidity of kaolin suspension. Using double coagulant (chitosan and tawas) have the removing turbidity greater than single coagulant.

Download Full-text

Aminocoumarins: A Privileged Precursor for the Synthesis of Fused Heterocycles

Current Organic Chemistry ◽

10.2174/1385272823666190514073610 ◽

2019 ◽

Vol 23 (9) ◽

pp. 1045-1075 ◽

Cited By ~ 1

Author(s):

Saigal ◽

Sumbulunnisan Shareef ◽

Habibur Rahman ◽

Md. Musawwer Khan

Keyword(s):

Chemical Reactivity ◽

Structural Systems ◽

Natural Occurrence ◽

Amino Group ◽

Active Compounds ◽

The Past ◽

Fused Heterocycles

Aminocoumarins are one of the important core structural systems, present in several biologically and medicinally active compounds. Owing to its natural occurrence, potential pharmacological applications and remarkable versatility as a privileged precursor, several proficient synthetic protocols have been reported in the literature over the past years. The presence of an amino group and enamine carbon enhances its chemical reactivity and thus such functionality is repeatedly used for the construction of various fused and simple heterocycles. This review highlights the preparation of different aminocoumarins and their applications for the construction of a variety of five, six and eight membered fused heterocycles.

Download Full-text

Investigation of the effect of ring size on the product distribution for the Schiff base reaction of 2-acetylcycloalkanones with diamino alkanes

Canadian Journal of Chemistry ◽

10.1139/v95-004 ◽

1995 ◽

Vol 73 (1) ◽

pp. 16-21 ◽

Cited By ~ 9

Author(s):

Raul G. Enriquez ◽

Juan M. Fernandez-G ◽

Ismael Leon ◽

William F. Reynolds ◽

Ji.-Ping Yang ◽

...

Keyword(s):

Schiff Base ◽

Condensation Reaction ◽

2D Nmr ◽

Product Distribution ◽

Major Product ◽

Ring Size ◽

Amino Group ◽

Amino Groups ◽

Bandgap Tunability in a One-Dimensional System

Condensed Matter ◽

10.3390/condmat3040034 ◽

2018 ◽

Vol 3 (4) ◽

pp. 34

Author(s):

Payal Wadhwa ◽

Shailesh Kumar ◽

T.J. Kumar ◽

Alok Shukla ◽

Rakesh Kumar

Keyword(s):

Solar Cells ◽

Periodic Potential ◽

Functional Group ◽

Potential Profile ◽

Dimensional System ◽

Natural Polymers ◽

One Dimensional ◽

Direct Bandgap ◽

Inorganic Systems ◽

Theoretical Investigations

The ability to tune the gaps of direct bandgap materials has tremendous potential for applications in the fields of LEDs and solar cells. However, lack of reproducibility of bandgaps due to quantum confinement observed in experiments on reduced dimensional materials, severely affects tunability of their bandgaps. In this article, we report broad theoretical investigations of direct bandgap one-dimensional functionalized isomeric system using their periodic potential profile, where bandgap tunability is demonstrated simply by modifying the potential profile by changing the position of the functional group in a periodic supercell. We found that bandgap in one-dimensional isomeric systems having the same functional group depends upon the width and depth of the deepest potential well at global minimum and derived correlations are verified for known synthetic as well as natural polymers (biological and organic), and also for other one-dimensional direct bandgap systems. This insight would greatly help experimentalists in designing new isomeric systems with different bandgap values for polymers and one-dimensional inorganic systems for possible applications in LEDs and solar cells.

Download Full-text

Removal of Organic Compounds with an Amino Group during the Nanofiltration Process

Membranes ◽

10.3390/membranes12010058 ◽

2021 ◽

Vol 12 (1) ◽

pp. 58

Author(s):

Renata Żyłła ◽

Magdalena Foszpańczyk ◽

Magdalena Olak-Kucharczyk ◽

Joanna Marszałek ◽

Stanisław Ledakowicz

Keyword(s):

Organic Compounds ◽

Natural Organic Matter ◽

Oxidation Product ◽

Membrane Filtration ◽

Separation Efficiency ◽

Ph Value ◽

Oxidation Products ◽

Low Molecular Weight ◽

Amino Group ◽

Amino Groups

The research covered the process of nanofiltration of low molecular weight organic compounds in aqueous solution. The article presents the results of experiments on membrane filtration of compounds containing amino groups in the aromatic ring and comparing them with the results for compounds without amino groups. The research was carried out for several commercial polymer membranes: HL, TS40, TS80, DL from various manufacturers. It has been shown that the presence of the amino group and its position in relation to the carboxyl group in the molecule affects the retention in the nanofiltration process. The research also included the oxidation products of selected pharmaceuticals. It has been shown that 4-Amino-3,5-dichlorophenol—a oxidation product of diclofenac and 4-ethylbenzaldehyde—a oxidation product of IBU, show poor separation efficiency on the selected commercial membranes, regardless of the pH value and the presence of natural organic matter (NOM). It has been shown that pre-ozonation of natural river water can improve the retention of pollutants removed.

Download Full-text

ANALISIS KONDUKTIVITAS DAN TERMAL PADA POLIMER ELEKTROLIT DARI KITOSAN/PVA/GLISEROL/LiClO4 UNTUK APLIKASI BATERAI ION LITIUM

CHEMISTRY PROGRESS ◽

10.35799/cp.14.1.2021.34074 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Nurhadini . ◽

Verry Andre Fabiani ◽

Megawati Ayu Putri ◽

Iin Lestari

Keyword(s):

Thermal Stability ◽

Polymer Electrolyte ◽

Functional Group ◽

Raw Materials ◽

Lithium Ion ◽

Electrolyte Composition ◽

Wave Number ◽

Natural Polymers ◽

Casting Method ◽

Absorption Intensity

Penggunaan polimer ramah lingkungan merupakan tantangan bagi industri baterai ion litium saat ini dikarenakan sifatnya yang mudah terbiodegradasi menjadi keunggulan polimer alam seperti kitosan dengan bahan baku dari alam yang melimpah. Komposisi polimer elektrolit dalam penelitian ini terdiri atas kitosan, PVA, gliserol yang didopan dengan LiClO4. Penelitian ini bertujuan untuk menganalisis sifat konduktivitas dan termal dari polimer elektrolit kitosan/PVA/gliserol/LiClO4. Pembuatan polimer elektrolit ini menggunakan metode casting. Peningkatan massa kitosan dalam komposisi polimer elektrolit menyebabkan adanya peningkatan intensitas pada bilangan gelombang 1718 cm-1 dan peningkatan intensitas serapan pada bilngangan gelombang 1271 cm-1 dengan masing-masing puncak serapan tersebut adalah gugus fungsi dari C=O dan gugus fungsi C-O. Berdasarkan data konduktivitas menunjukkan bahwa komposisi 70/30/20/20 (kitosan /PVA/Gliserol/LiClO4) memiliki konduktivitas tertinggi sebesar 4,8 x 10-5S/cm. Hasil kurva TGA menunjukkan stabilitas termal komposisi polimer elektrolit hingga 210oC dan peningkatan jumlah kitosan dalam polimer elektrolit menurunkan kestabilan termal. Polimer elektrolit dari kitosan/PVA/Gliserol/LiClO4 dapat diaplikasikan untuk baterai ion litium berdasarkan analisis konduktivitas ionik dan kestabilan termal. ABSTRACT The use of environmentally friendly polymers is a challenge for the lithium-ion batteries industry today because its biodegradable nature is an advantage of natural polymers such as chitosan with abundant raw materials from nature. The polymer electrolyte composition in this study consisted of chitosan, PVA, glycerol doped with LiClO4. This study aims to analyze the conductivity and thermal properties of the polymer electrolyte chitosan/PVA/Glycerol/LiClO4. The polymer electrolyte was made using a casting method. The increasing of the chitosan mass in the polymer electrolyte composition led to an increase in intensity at the wave number 1718 cm-1 and an increase in absorption intensity at the wavenumber of 1271 cm-1 with absorption peaks being a functional group of C=O and C-O respectively. Based on the conductivity data, it showed that the composition of 70/30/20/20 (chitosan/PVA/Glycerol/LiClO4) had the highest conductivity of 4.8 x 10-5S/cm. The results of the TGA curve illustrated that polymer electrolyte had thermal stability until 210oC and the increasing amount of chitosan of polymer electrolyte decreased thermal stability. Polymer electrolyte chitosan

Download Full-text

Anomalous phase behavior in blends of -SO3H terminated polystyrene with poly(n-butyl acrylate) containing a small amount of tertiary amino groups

e-Polymers ◽

10.1515/epoly.2008.8.1.917 ◽

2008 ◽

Vol 8 (1) ◽

Author(s):

Kenji Yamamoto ◽

Ayumi Nanakno ◽

Hiroyasu Masunaga ◽

Isamu Akiba

Keyword(s):

Butyl Acrylate ◽

Stoichiometric Composition ◽

Phase Region ◽

Molar Ratio ◽

Amino Group ◽

Amino Groups ◽

Two Phase ◽

Dimethylaminoethyl Methacrylate ◽

X Ray Scattering ◽

Tertiary Amino

Abstract Phase behavior in the blend of -SO3H terminated polystyrene (PSS) with poly(n-butyl acrylate-co-N,N-dimethylaminoethyl methacrylate) containing 6.0 mol% N,N-dimethylaminoethyl methacrylate (P1) is investigated by optical microscopy and small-angle X-ray scattering (SAXS). Comparing the miscibility of polystyrene/P1 blend, it is confirmed that the miscibility of the PSS/P1 blend is drastically improved by the hydrogen bonds between -SO3H and tertiary amino group. In addition, two-phase region of the PSS/P1 blend is split into two regions around the stoichiometric composition, in which the molar ratio of -SO3H to tertiary amino group is 1:1 stoichiometry. SAXS result shows that the PSS/P1 blend at stoichiometric composition forms a block copolymer-like aggregate and it takes a disorder state.

Download Full-text

pKa-Werte von Ethidiumbromid und 7-Amino-9-phenyl-10- äthyl-phenanthridinium-bromid / pKa-Values of Ethidiumbromide and 7-Amino-9-phenyl-10-ethyl-phenanthridinium- bromide

Zeitschrift für Naturforschung C ◽

10.1515/znc-1976-11-1205 ◽

1976 ◽

Vol 31 (11-12) ◽

pp. 656-660 ◽

Cited By ~ 12

Author(s):

Ingfried Zimmermann ◽

Herbert Zimmermann

Keyword(s):

Electronic Spectra ◽

Water Solution ◽

Ph Dependence ◽

Quantum Mechanical ◽

Amino Group ◽

Quantum Mechanical Calculations ◽

Acidic Water ◽

Amino Groups ◽

Electronic Density ◽

Decreasing Ph

Abstract Ethidiumbromide (1) has two amino groups in 2-and 7-position which are protonated in acidic water solution. Both pKa-values of 1 are determined at 20 °C by means of the pH-dependence of the electronic spectra using a iterative calculating procedure, pKa1 = 0.713, pKa2 = 2.43. Acetylation of 1 and quantum mechanical calculations lead to the conclusion that the electronic density at the 7-amino group is greater than in 2-position. Therefore with decreasing pH preferably the 7-amino group is protonated (pKa2). followed by the protonation of the 2-amino group (pKa1). The pKa of 7-amino-9-phenyl-10-ethyl-phenanthridinium-bromide in water solution at 20 °C is determined to pKa= 1 .2 5 .

Download Full-text

Room-temperature dissolution and chemical modification of cellulose in aqueous tetraethylammonium hydroxide–carbamide solutions

Cellulose ◽

10.1007/s10570-019-02907-x ◽

2019 ◽

Vol 27 (4) ◽

pp. 1933-1950 ◽

Cited By ~ 4

Author(s):

Juho Antti Sirviö ◽

Juha P. Heiskanen

Keyword(s):

Chemical Modification ◽

Charge Density ◽

Microcrystalline Cellulose ◽

Room Temperature ◽

Molar Ratio ◽

Cellulose Modification ◽

Tetraethylammonium Hydroxide ◽

Cellulose Concentration

AbstractThe room-temperature dissolution of cellulose in aqueous tetraethylammonium hydroxide (TEAOH) in the presence of carbamides (ureas) was investigated. Without carbamide, 35 wt% TEAOH was able to dissolve cellulose (microcrystalline cellulose) up to 3 wt%, whereas carbamides—such as urea, N-methylurea, N-ethylurea, 1,3-dimethylurea, and imidazolidone—were able to improve the dissolution of cellulose. At 5 wt% cellulose concentration, the highest carbamide contents in the solvent still able to dissolve cellulose within 1 h were 56 and 55 wt% of 1,3-dimethylurea and N-methylurea, respectively. When using urea, up to 15% of cellulose could be dissolved in a solution containing 22 wt% of urea. To demonstrate the possibility of the use of a carbamide-based solvent in cellulose modification, cationic cellulose was produced using glycidyltrimethylammonium chloride (GTAC). At a molar ratio of 1:3 of cellulose and GTAC, all the studied TEAOH–carbamide solvents produce cationic cellulose with higher charge density compared to the reference NaOH–urea solvent.

Download Full-text