Infrared Analysis of Isomerized, Vulcanized, and Oxidized Natural Rubber

1955 ◽  
Vol 28 (1) ◽  
pp. 213-223 ◽  
Author(s):  
G. Salomon ◽  
A. Chr van der Schee
Keyword(s):  
Double Bond ◽  
Infrared Spectrum ◽  
Natural Rubber ◽  
Infrared Spectra ◽  
Infrared Analysis ◽  
Side Group ◽  
Oxidation Reactions ◽  
Absorption Bands ◽  
Group Ii

Abstract This paper is a continuation of our study on the infrared spectra of natural rubber and its derivatives. It was found previously that, in certain reactions of rubber, the original double bond (I) is shifted to the side group (II) and that this leads to significant changes in the chemical and mechanical behavior of the polymer. Others have also reported the occurrence of groups (II) and (III) in rubber and certain rubber derivatives. Group (II) is also found in synthetic polyisoprenes as a result of 3,4-polymerization. We have now measured the intensities of the absorption bands of the rubber spectrum and changes produced by cyclization and isomerization. Certain statements on the formation of (II) and (III) during vulcanization were at variance with our experience, but a detailed investigation cleared up some misconceptions. Modifications brought about by oxidation are chemically related to those produced by sulfuration reactions. A classification of oxidation reactions, based on typical changes in the infrared spectrum, will be proposed in the discussion.

Gaseous infrared spectra of the simplest geminal diol CH2(OH)2 and the isotopic analogues in the hydration of formaldehyde

2021 ◽  
Author(s):  
Hung-Yang Jain ◽  
Chih-Tsun Yang ◽  
Li-Kang Chu
Keyword(s):  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Absorption Bands ◽  
Geminal Diol

The infrared spectrum of the simplest geminal diol, methanediol or methylene glycol (CH2(OH)2), was successfully probed in the gaseous hydration of formaldehyde. The observed absorption bands coincided with the anharmonic...

A spectroscopic study of proton transfer and photochromism in N-(2-hydroxybenzylidene)aniline

1982 ◽  
Vol 60 (13) ◽  
pp. 1738-1746 ◽  
Author(s):  
J. W. Lewis ◽  
C. Sandorfy
Keyword(s):  
Double Bond ◽  
Low Temperature ◽  
Infrared Spectrum ◽  
Spectroscopic Study ◽  
Title Compound ◽  
Spectral Characteristics ◽  
Absorption Bands ◽  
Central Carbon ◽  
Infrared Spectral ◽  
Nitrogen Double Bond

The infrared spectral characteristics of N-(2-hydroxybenzylidene)aniline, its deuterium substituted analogue, N-(2-hydroxybenzylidene)-m-toluidine, and their photoproducts have been investigated. The infrared spectrum of a low temperature polycrystalline film of N-(2-hydroxybenzylidene)aniline exhibits new absorption bands at 3380, 1646, 1537, 1502, 1319, and 1310 cm−1 upon irradiation at 365 nm. Likewise, the spectrum of the m-toluidine derivative exhibits new absorption bands at 3320, 1650, 1535, 1503, 1321, 1310, and 995 cm−1 upon irradiation at 365 nm. These new data, in conjunction with the newly acquired data on the hydrochloride and deuterochloride of the title compound, indicate that the photoproduct is a zwitterion, not an ortho-quinone. It is also inferrred that the photoproduct exists in a conformation which is cis about the central carbon–nitrogen double bond.

Low-Temperature Grinding Technique for Infrared Analysis of Propellants and Binders in Potassium Bromide Disks

1968 ◽  
Vol 22 (5) ◽  
pp. 491-493 ◽  
Author(s):  
A. S. Tompa
Keyword(s):  
Low Temperature ◽  
Thermal Degradation ◽  
Infrared Spectra ◽  
Potassium Bromide ◽  
Infrared Analysis ◽  
Absorption Bands ◽  
Grinding Technique ◽  
Disk Method ◽  
Grinding Time ◽  
Infrared Absorption Bands

A low-temperature grinding technique for the potassium bromide pressed-disk method was developed to obtain quantitative infrared spectra of propellants and propellant binders. The effects of grinding time and temperature on the intensities of infrared absorption bands were determined. The technique was applied to the study of the thermal degradation of a polyurethane propellant.

One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

2018 ◽  
Vol 15 (3) ◽  
pp. 380-387
Author(s):  
Xia Zhao ◽  
Xiaoyu Lu ◽  
Lipeng Zhang ◽  
Tianjiao Li ◽  
Kui Lu
Keyword(s):  
Double Bond ◽  
Efficient Method ◽  
Room Temperature ◽  
Sulfonyl Chloride ◽  
Antibacterial Activities ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

Functional Classification of Feed Items in Pampa Grassland, Based on Their Near-Infrared Spectrum

2020 ◽  
Vol 73 (3) ◽  
pp. 358-367
Author(s):  
Júlio Cezar Rebés Azambuja Filho ◽  
Paulo Cesar de Faccio Carvalho ◽  
Olivier Jean François Bonnet ◽  
Denis Bastianelli ◽  
Magali Jouven
Keyword(s):  
Infrared Spectrum ◽  
Near Infrared ◽  
Functional Classification ◽  
Near Infrared Spectrum

scholarly journals Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the Be6B11− Fluxional Cluster

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 112
Author(s):  
Carlos Emiliano Buelna-Garcia ◽  
José Luis Cabellos ◽  
Jesus Manuel Quiroz-Castillo ◽  
Gerardo Martinez-Guajardo ◽  
Cesar Castillo-Quevedo ◽  
...  
Keyword(s):  
Free Energy ◽  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Thermal Effects ◽  
Global Minimum ◽  
Energy Surface ◽  
Weighted Sums ◽  
Free Energy Surface ◽  
Temperature Dependent ◽  
Relative Population

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on Be6B11− clusters and the effect of temperature on their infrared spectroscopy and relative populations. We identify the vibration modes possessed by the cluster that significantly contribute to the zero-point energy. A couple of steps are considered for computing the temperature-dependent relative population: First, using a genetic algorithm coupled to density functional theory, we performed an extensive and systematic exploration of the potential/free energy surface of Be6B11− clusters to locate the putative global minimum and elucidate the low-energy structures. Second, the relative populations’ temperature effects are determined by considering the thermodynamic properties and Boltzmann factors. The temperature-dependent relative populations show that the entropies and temperature are essential for determining the global minimum. We compute the temperature-dependent total infrared spectra employing the Boltzmann factor weighted sums of each isomer’s infrared spectrum and find that at finite temperature, the total infrared spectrum is composed of an admixture of infrared spectra that corresponds to the spectra of the lowest-energy structure and its isomers located at higher energies. The methodology and results describe the thermal effects in the relative population and the infrared spectra.

scholarly journals Common binding mechanism and classification of Group II and III WW domains

2003 ◽  
Vol 43 (supplement) ◽  
pp. S93
Author(s):  
Y. Kato ◽  
K. Nagata ◽  
Marius Sudol ◽  
M. Tanokura
Keyword(s):  
Binding Mechanism ◽  
Ww Domains ◽  
Group Ii

Chlorination of Natural Rubber in Solution with Gaseous Chlorine

1953 ◽  
Vol 26 (4) ◽  
pp. 902-911 ◽  
Author(s):  
C. S. Ramakrishnan ◽  
D. Raghunath ◽  
J. B. Pande
Keyword(s):  
Double Bond ◽  
Natural Rubber ◽  
Cyclization Reaction ◽  
Double Bonds ◽  
Chlorine Atoms ◽  
Reaction Stage ◽  
Stage 1 ◽  
Additive Reaction

Abstract The chlorination of rubber solutions by gaseous chlorine was followed by isolating the partially chlorinated products and preparing their ozonides. The ozonides were hydrolyzed, and the acids and aldehydes formed on hydrolysis were determined. By a comparison with the amounts of acids and aldehydes obtained from ozonides of unreacted rubber, the amount of residual isoprenic double bonds present was found. The loss of double bonds attending the introduction of chlorine atoms into the molecule of rubber indicates four definite stages in chlorination : (1) initial substitutive attack by chlorine, with concomitant cyclization, resulting in a loss of one double bond between two isoprenic units, (2) substitution, (3) additive reaction, and (4) essentially substitution. Chlorination of aged rubber solutions differs from the above in that the cyclization reaction (stage 1) seems to be absent.

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