The Use of Deutero Compounds as Indicators for the Presence of Free Radicals in Organic Decomposition Reactions

1937 ◽  
Vol 5 (5) ◽  
pp. 372-372
Author(s):  
E. W. R. Steacie ◽  
W. A. Alexander
Keyword(s):  
Free Radicals ◽  
Decomposition Reactions ◽  
Organic Decomposition

FREE RADICALS IN ORGANIC DECOMPOSITION REACTIONS: I. THE THERMAL DECOMPOSITION OF MIXTURES OF METHYL ETHER AND DEUTERO-ACETONE

1937 ◽  
Vol 15b (7) ◽  
pp. 295-304
Author(s):  
E. W. R. Steacie ◽  
W. A. Alexander
Keyword(s):  
Free Radicals ◽  
Methyl Ether ◽  
Experimental Error ◽  
Radical Mechanism ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Decomposition Reactions ◽  
Free Radical Mechanism ◽  
Insight Into ◽  
Organic Decomposition

A new method of obtaining information concerning the participation of free radicals in decomposition reactions is described. A mixture of two organic compounds is decomposed, all the hydrogen in one of the compounds having been replaced by deuterium. By an examination of the distribution of deuterium among the products, it is possible to obtain considerable insight into the mechanism of the process.Mixtures of deutero-acetone and dimethyl ether have been decomposed at 590 °C. It is found that the hydrogen in the products is entirely "light" within the experimental error. This precludes the possibility that formaldehyde (which is the source of the hydrogen) decomposes by a free radical mechanism, HCHO = H + CHO, as otherwise reaction of hydrogen atoms with deutero-acetone would lead to the formation of HD.It is also concluded that it is unlikely that formaldehyde formed in the methyl ether decomposition is decomposed by sensitization from methyl radicals from the ether decomposition. If this were the case we would expect to have the reactions[Formula: see text]and again hydrogen atoms by reaction with deutero-acetone would yield HD.The method of investigation seems to have interesting possibilities and to be of wide applicability.

scholarly journals Effects of calcium on the evolution of nitrogen during pyrolysis of a typical low rank coal

2019 ◽  
Vol 7 (2) ◽  
pp. 397-404
Author(s):  
Xiongchao Lin ◽  
Sasha Yang ◽  
Xujun Chen ◽  
Panpan Zheng ◽  
Yonggang Wang ◽  
...  
Keyword(s):  
Free Radicals ◽  
Pyrolysis Temperature ◽  
Low Rank ◽  
Mineral Matter ◽  
Condensation Polymerization ◽  
Coal Pyrolysis ◽  
Decomposition Reactions ◽  
Gaseous Products ◽  
Secondary Reactions ◽  
Different Temperatures

AbstractThis study aims to investigate the effects of calcium on the migration of nitrogen in coal (coal-N) to N-containing gas species, particularly, NH3 and HCN (volatile-N) in volatiles, as well as the chemical transformation of the N in char during coal pyrolysis under different temperatures. The pyrolysis experiments of Shengli brown coal and its derived coal samples loaded with different contents of calcium were conducted under 600–800 °C in a novel fluidized bed reactor. The experimental results showed that during coal pyrolysis, the generation of NH3 is mainly derived from secondary reactions among volatiles, tar and char with the catalytic effect of mineral matter, especially calcium in coal. Increasing pyrolysis temperature from 600 to 800 °C could enhance the release of N in coal to volatiles. Meanwhile, the increased pyrolysis temperature could also inhibit the generation of NH3 while facilitating the formation of HCN. The release of HCN is more sensitive to pyrolysis temperatures. Specifically, under higher pyrolysis temperatures, more N-containing structures in coal would become thermally unstable and crack into HCN; On the other hand, higher pyrolysis temperature could also enhance the decomposition of N in coal to N-containing species in tar or N2, thus reducing the release of HCN and NH3. Nitrogen in tar could either undergo secondary decomposition reactions, generating NH3, HCN, N2 and other N-containing species in gas phase, or experience condensation polymerization by forming macromolecular structure and be retained in char at high pyrolysis temperatures. Calcium could significantly restrain the release of N from coal, thus reducing the yields of NH3 and HCN. During coal pyrolysis, calcium catalytically enhances the fracture and combination of chemical bonds, generating abundant free radicals. These free radicals could continuously attack N-containing structures and consequently release the N-containing gaseous products, such as NH3, HCN, N2 etc., resulting in the decrease of N in char. Calcium also plays important roles in nitrogen transformation in char during coal pyrolysis by catalytically intensifying the transformation of N in char from pyridinic nitrogen (N-6) and pyrrolic nitrogen (N-5) to quaternary type nitrogen (N-Q) during coal pyrolysis.

FREE RADICALS BY MASS SPECTROMETRY: XV. THE: MERCURY-PHOTOSENSITIZED DECOMPOSITION OF FORMIC ACID, ACETIC ACID, AND METHYL FORMATE

1959 ◽  
Vol 37 (2) ◽  
pp. 389-402 ◽  
Author(s):  
P. Kebarle ◽  
F. P. Lossing
Keyword(s):  
Acetic Acid ◽  
Free Radicals ◽  
Formic Acid ◽  
Methyl Formate ◽  
Intramolecular Rearrangement ◽  
Significant Extent ◽  
Alternative Mode ◽  
Decomposition Reactions ◽  
Intramolecular Rearrangements ◽  
No Free Radicals

The Hg(3P1) photosensitized decomposition of formic acid proceeds by two intramolecular rearrangement reactions, leading respectively to H2O and CO, and to H2 and CO2. No free radicals are produced. The decomposition reactions of methyl formate and of acetic acid proceed predominantly by the formation of free radicals, but intramolecular rearrangements also occur to a significant extent. For both these latter compounds the evidence suggests the occurrence of two modes of dissociation into free radicals:[Formula: see text]No evidence for the alternative mode of dissociation[Formula: see text]was found.

Reaction Mechanism of the Multi-channel Decomposition Reactions of 1-Pentenyl Free Radicals

2008 ◽  
Vol 26 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Xue-Li CHENG ◽  
Yan-Yun ZHAO ◽  
Feng LI ◽  
Li-Qing LI ◽  
Xiu-Jun TAO
Keyword(s):  
Free Radicals ◽  
Reaction Mechanism ◽  
Decomposition Reactions ◽  
Channel Decomposition

A computational study of pyrolysis reactions of lignin model compounds

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Thomas Elder
Keyword(s):  
Free Radicals ◽  
Computational Study ◽  
Closed Shell ◽  
Phenyl Ether ◽  
Electron Delocalization ◽  
Unimolecular Decomposition ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Decomposition Reactions ◽  
Lignin Model

Abstract Enthalpies of reaction for the initial steps in the pyrolysis of lignin have been evaluated at the CBS-4m level of theory using fully substituted β-O-4 dilignols. Values for competing unimolecular decomposition reactions are consistent with results previously published for phenethyl phenyl ether models, but with lowered selectivity. Chain propagating reactions of free radicals with a closed-shell dilignol are dominated by structures in which extensive electron delocalization occurs.

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