scholarly journals Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

2013 ◽  
Vol 9 ◽  
pp. 2751-2761 ◽  
Author(s):  
Valerij A Nikolaev ◽  
Alexey V Ivanov ◽  
Ludmila L Rodina ◽  
Grzegorz Mlostoń
Keyword(s):  
Elevated Temperature ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Product Type ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Cascade Process ◽  
Energy Profile

Acyclic diazodicarbonyl compounds react at room temperature with cycloaliphatic thioketones, e.g. 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one and adamantanethione, via a cascade process in which the key step is a 1,5-electrocyclization of the intermediate thiocarbonyl ylide leading to tetrasubstituted spirocyclic 1,3-oxathioles. The most reactive diazodicarbonyl compound was diazoacetylacetone. In the case of dimethyl diazomalonate competitive 1,3-electrocyclization yielded the corresponding thiirane at elevated temperature, which after spontaneous desulfurization produced a tetrasubstituted alkene. To explain the observed temperature dependence of the main reaction product type obtained from dimethyl diazomalonate and 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one as well as to verify reversibility of the thiocarbonyl ylide and 1,3-oxathiole interconversion, the calculations of the energy profile for the transformation of 1,3-oxathiole to alkene were performed at the DFT PBE1PBE/6-31G(d) level.

Investigations on Phosphate Cements Hardening at Room Temperature

1989 ◽  
Vol 179 ◽  
Author(s):  
Alfred Zurz ◽  
I. Odler ◽  
B. Dettki
Keyword(s):  
Ultimate Strength ◽  
Room Temperature ◽  
Main Reaction ◽  
Main Reaction Product

AbstractPastes prepared from diammonium orthophosphate and calcined magnesia, MgO, exhibit a fast setting and hardening associated with NH3 liberation. Struvite, MgNH4PO4.6H2O, was found to be the main reaction product. Pastes made with NaH2PO4 or Na-polyphosphate exhibit a similar hardening reaction. The hardening reaction may be retarded and the ultimate strength moderately increased by adding appropriate retarders, such as Na2B4O7 10H2O to the system. The quality of the used MgO and its fineness has a significant effect on the rate of the hardening reaction.

REACTION OF OXYGEN ATOMS WITH BENZENE

1961 ◽  
Vol 39 (12) ◽  
pp. 2436-2443 ◽  
Author(s):  
G. Boocock ◽  
R. J. Cvetanović
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Room Temperature ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Kcal Mole ◽  
Volatile Material ◽  
Formed Adduct ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

The reaction of benzene with oxygen atoms produced by mercury photosensitized decomposition of nitrous oxide has been studied in a circulating system at room temperature. The main reaction product is a non-volatile material probably largely aldehydic in character. This is tentatively assumed to result from the rearrangement and polymerization of the initially formed adduct. Smaller amounts of phenol and carbon monoxide are also formed. The rate of formation of carbon monoxide decreases with increasing pressure, suggesting an energy-rich precursor.Oxygen atoms react with benzene much more slowly than with olefines. At 120° cyclopentene reacts about 150 times more quickly than benzene. The activation energy of the reaction of oxygen atoms with benzene has been estimated at 4.6 to 4.9 kcal/mole, with an uncertainty of about 0.7 kcal/mole.

Ion-Enhanced Chemical Reaction of XeF2 with Silicon by Modulated Molecular Beam Mass Spectrometry

1984 ◽  
Vol 38 ◽  
Author(s):  
M. Balooch ◽  
D. R. Olander ◽  
W. J. Siekhaus
Keyword(s):  
Mass Spectrometry ◽  
Surface Temperature ◽  
Chemical Reaction ◽  
Room Temperature ◽  
Molecular Beam ◽  
Ion Beam ◽  
Reaction Probability ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Molecular Beam Mass Spectrometry

AbstractThe reaction of XeF2 with the Si(100) surface was studied by modulated (10–1000 Hz) molecular beam-mass spectrometry in the temperature range 300–1300K and equivalent XeF2 pressure of 5×10−6 to 10−4 Torr. Simultaneous bombardment of the reacting surface by Ar+ was used to determine the extent of ion-enhancement of the reaction.In the absence of the ion beam, the main reaction product was SiF4, which was formed with a reaction probability of ˜5×10−2 at room temperature. In the presence of the ion beam three products, SiF4, SiF2 and F2 (or F), were detected with formation probabilities of ˜1×10−1, 6×10−2 and 7×10−2 respectively. Increasing surface temperature reduced the ion-enhanced reactivity.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

scholarly journals Temperature dependence of the rigid amorphous fraction of poly(butylene succinate)

RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25731-25737
Author(s):  
Maria Cristina Righetti ◽  
Maria Laura Di Lorenzo ◽  
Patrizia Cinelli ◽  
Massimo Gazzano
Keyword(s):  
Body Temperature ◽  
Temperature Dependence ◽  
Human Body ◽  
Room Temperature ◽  
Rigid Amorphous Fraction ◽  
Butylene Succinate ◽  
Amorphous Fraction ◽  
Human Body Temperature ◽  
Rigid Amorphous

At room temperature and at the human body temperature, all the amorphous fraction is mobile in poly(butylene succinate).

The Static Mechanical Property of Concrete at Elevated Temperature

2011 ◽  
Vol 261-263 ◽  
pp. 212-216
Author(s):  
Jun Lin Tao ◽  
Li Bo Qin ◽  
Kui Li ◽  
Bin Jia
Keyword(s):  
Mechanical Property ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Critical Strain ◽  
Plain Concrete ◽  
Constitutive Relationship ◽  
Heating Method ◽  
Experiment System ◽  
Wave Heating ◽  
Static Mechanical

Using micro-wave heating method, the previous disadvantages of heating slowly and non-uniform are broken through. And plain concrete high temperature loading experiment system is composed of the method and material experiment machine. Many experiments of self-made concrete are carried out from room temperature to 600°C by this system. The strength and critical strain of concrete with temperature are obtained, and through analysis of the compressive stress-strain curves under different temperature, the constitutive relationship is established. The result shows that this constitutive relationship is greatly agrees with experiment. Meanwhile, the phenomenon is analyzed and explained in the progress of experiment.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Electrical and Optical Properties of Si+ and P+ Implanted InP:Fe

1990 ◽  
Vol 201 ◽  
Author(s):  
Honglie Shen ◽  
Genqing Yang ◽  
Zuyao Zhou ◽  
Guanqun Xia ◽  
Shichang Zou
Keyword(s):  
Optical Properties ◽  
Silicon Nitride ◽  
Temperature Dependence ◽  
Optimal Condition ◽  
Room Temperature ◽  
Broad Band ◽  
Photoluminescence Spectra ◽  
Electrical And Optical Properties ◽  
Spectrum Measurement ◽  
Single Implant

AbstractDual implantations of Si+ and P+ into InP:Fe were performed both at 200°C and room temperature. Si+ ions were implanted by 150keV with doses ranging from 5×1013 /cm2 to 1×1015 /cm2, while P+ ions were implanted by 110keV. 160keV and 180keV with doses ranging from 1×l013 /cm2 to 1×1015 /cm2. Hall measurements and photoluminescence spectra were used to characterize the silicon nitride encapsulated annealed samples. It was found that enhanced activation can be obtained by Si+ and P+ dual implantations. The optimal condition for dual implantations is that the atomic distribution of implanted P overlaps that of implanted si with the same implant dose. For a dose of 5×l014 /cm2, the highest activation for dual implants is 70% while the activation for single implant is 40% after annealing at 750°C for 15 minutes. PL spectrum measurement was carried out at temperatures from 11K to 100K. A broad band at about 1.26eV was found in Si+ implanted samples, of which the intensity increased with increasing of the Si dose and decreased with increasing of the co-implant P+ dose. The temperature dependence of the broad band showed that it is a complex (Vp-Sip) related band. All these results indicate that silicon is an amphoteric species in InP.

Temperature dependence of chlorine-35 N.Q.R. in 2,6-Dichlorophenol

1978 ◽  
Vol 31 (4) ◽  
pp. 791 ◽  
Author(s):  
R Chandramani ◽  
SP Basavaraju ◽  
N Devaraj
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Brown's Method

Chlorine n.q.r, in 2,6-dichlorophenol has been investigated at temperatures from 77 K to room temperature. Two resonance lines due to chemically inequivalent sites have been observed throughout this temperature range. Torsional frequencies of the molecule have been calculated at temperatures from 77 to 300 K according to Bayer's theory and Brown's method. Also the temperature coefficients of the torsional frequencies have been calculated.

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