Preparation of Radioactively Tagged Ethylene-Propylene Copolymers. Calculation of the Block-Length Distribution from the Kinetic Data

1977 ◽  
Vol 50 (5) ◽  
pp. 988-995
Author(s):  
J. Exner ◽  
M. Seeger ◽  
H-J. Cantow
Keyword(s):  
Thermal Decomposition ◽  
Gas Chromatography ◽  
Double Bond ◽  
Kinetic Data ◽  
Length Distribution ◽  
Methyl Groups ◽  
Sequence Distribution ◽  
Ethylene Propylene ◽  
Tertiary Carbon ◽  
Radioactive Counting

Abstract A series of statistical copolymers is available for our studies of the mechanisms of thermal decomposition of ethylene-propylene copolymers and their sequence distribution. However, the analytical evidence can be improved appreciably by the use of radioactively tagged copolymers and radio-gas chromatography. A loss of information occurs when untagged polymers undergo α-scission. Even if the chain breaks directly at the tertiary carbon atom, the scission product stabilizes itself by forming a terminal double bond. Accordingly, the position of double bonds gives no information about the location of methyl side groups in copolymers. However, if the α-methyl groups are radioactively tagged, as shown in the formula above, radioactive counting of linear fragments can demonstrate their original methyl side groups. Thus, α-scissions of copolymers can be directly determined.

Determination of the composition of ethylene-propylene copolymers by pyrolytic gas chromatography

1985 ◽  
Vol 27 (5) ◽  
pp. 1242-1247 ◽  
Author(s):  
A.V. Bratchikov ◽  
B.A. Berendeyev ◽  
A.G. Rodionov
Keyword(s):  
Gas Chromatography ◽  
Ethylene Propylene

scholarly journals Crystal structure ofN′′-benzyl-N′′-[3-(benzyldimethylazaniumyl)propyl]-N,N,N′,N′-tetramethylguanidinium bis(tetraphenylborate)

2015 ◽  
Vol 71 (12) ◽  
pp. o1086-o1087
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Positive Charge ◽  
Planar Geometry ◽  
Methyl Groups ◽  
Two Dimensional ◽  
Single Bond ◽  
Double Bond Character ◽  
Bond Lengths ◽  
Bond Character

In the crystal structure of the title salt, C24H38N42+·2C24H20B−, the C—N bond lengths in the central CN3unit of the guanidinium ion are 1.3364 (13), 1.3407 (13) and 1.3539 (13) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3plane. The bonds between the N atoms and the terminal methyl groups of the guanidinium moiety and the four C—N bonds to the central N atom of the (benzyldimethylazaniumyl)propyl group have single-bond character. In the crystal, C—H...π interactions between the guanidinium H atoms and the phenyl C atoms of the tetraphenylborate ions are present, leading to the formation of a two-dimensional supramolecular pattern parallel to theacplane.

Identifying Thermal Decomposition Products of Nitrate Ester Explosives Using Gas Chromatography–Vacuum Ultraviolet Spectroscopy: An Experimental and Computational Study

2020 ◽  
Vol 74 (12) ◽  
pp. 1486-1495 ◽  
Author(s):  
Courtney A. Cruse ◽  
Jingzhi Pu ◽  
John V. Goodpaster
Keyword(s):  
Thermal Decomposition ◽  
Gas Chromatography ◽  
Density Functional ◽  
Vacuum Ultraviolet ◽  
Computational Study ◽  
Ultraviolet Spectroscopy ◽  
Decomposition Products ◽  
Nitrate Ester ◽  
Vacuum Ultraviolet Spectroscopy ◽  
Synchrotron Spectroscopy

Analysis of nitrate ester explosives (e.g., nitroglycerine) using gas chromatography–vacuum ultraviolet spectroscopy (GC–VUV) results in their thermal decomposition into nitric oxide, water, carbon monoxide, oxygen, and formaldehyde. These decomposition products exhibit highly structured spectra in the VUV that is not seen in larger molecules. Computational analysis using time-dependent density functional theory (TDDFT) was utilized to investigate the excited states and vibronic transitions of these decomposition products. The experimental and computational results are compared with those in previous literature using synchrotron spectroscopy, electron energy loss spectroscopy (EELS), photoabsorption spectroscopy, and other computational excited state methods. It was determined that a benchtop GC–VUV detector gives comparable results to those previously reported, and TDDFT could predict vibronic spacing and model molecular orbital diagrams.

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