Pyrolyse von Aromaten. 1. Mitteilung. Biphenyl

Gäumann, Tino; Rayroux, J. M.

doi:10.1002/hlca.19620450522

Cited by 10 publications

(3 citation statements)

References 6 publications

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“…Many experimental and theoretical studies on model compounds have been carried out, including aromatic hydrocarbon compounds [11][12][13][14][15][16][17][18][19][20][21][22][23], ethers compounds (aromatic ethers [24][25][26][27][28][29][30][31] and ester ethers [32,33]), carboxylic acids [34], and heterocyclic aromatic compounds [35][36][37][38] bond dissociation enthalpies (BDE) of the oxygen-carbon and carbon-carbon bonds in substituted phenethyl phenyl ethers (PPEs) which representing the dominant b-O-4 ether linkage [28], and C a AO and C a AC b BDEs for a series of b-5 arylcoumaran [29]. They also examined the substituent effects on these bond dissociation enthalpies.…”

Section: Introductionmentioning

confidence: 99%

A theoretical study on bond dissociation enthalpies of coal based model compounds

Fan

2015

Fuel

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Section: Introductionmentioning

confidence: 99%

A theoretical study on bond dissociation enthalpies of coal based model compounds

Fan

2015

Fuel

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“…Several studies on the pyrolysis of α,ω-diarylalkanes, which serve as the model aliphatic cross-links in coal and biomass, have been performed over the recent past 3 decades. Gaumann and Rayroux, and Fields and Meyerson studied the pyrolysis of biphenyl at 773 K and found that terphenyls, quaterphenyls, benzene, and hydrogen were produced. Rossi et al reported the thermolysis of diphenylmethane at 1023–1248 K under very low pressure pyrolysis (VLPP) conditions and found that the carbon–carbon and carbon–hydrogen bond cracking is competitive.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Investigation on Three α,ω-Diarylalkane Pyrolysis

Jin

et al. 2014

Energy Fuels

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Pyrolysis of three α,ω-diarylalkane compounds (biphenyl, diphenylmethane, and bibenzyl) was performed below 30 Pa between 573 and 1473 K. Vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry was used to detect the reactants, radicals, and products. The relative concentration profiles of the pyrolysis species were estimated by a semiquantitative analysis method. Experimental results indicated that the length of the C−C bridge bond plays an influential role in cracking of corresponding bonds in the α,ω-diarylalkane pyrolysis process. The C−H bond scission is dominant in pyrolysis of diphenylmethane at low temperatures, while the C−C bond scission competes with it when the temperature increases. The symmetrical homolysis of bibenzyl is a dominant reaction at low temperatures and will compete with the unsymmertrical cleavage reaction with increase of the temperature. In addition, the formation mechanism of fluorene, which plays a significant role in polycyclic aromatic hydrocarbon generation, during diphenylmethane pyrolysis was discussed by combining the experimental observation with the theoretical calculation. The theoretical calculation supported these experimental results at the mPW2PLYP level.

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“…Significantly fewer studies of simple biphenyl hydrogenolysis have been reported. Pure biphenyl pyrolyzes very slowly at temperatures below 500 °C, producing terphenyl and quaterphenyl oligomers and a minor amount of benzene. , Proksch et al have reported that holding times of 5−20 h are required at 420−465 °C to produce <1 wt % biphenyl conversion. Significantly higher rates of conversion were observed at 700 °C, yielding similar mixtures of terphenyl, quaterphenyl, and benzene …”

Section: Introductionmentioning

confidence: 99%

Hydrogen Transfer Induced Cleavage of Biaryl Bonds

et al. 1997

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Biaryl bonds are the strongest carbon−carbon single bonds in fossil fuels. This paper examines hydrogenolysis and alkane cohydrogenolysis of biphenyl and dimethylbiphenyls, in detail. Biphenyl cleavage was found to be enhanced by copyrolysis and cohydrogenolysis with small amounts of 2,2,3,3-tetramethylbutane (hexamethylethane, HME). Much smaller enhancements were found for cohydrogenolysis with other alkanes. Increased biaryl cleavage rates, in HME cohydrogenolysis, were found to be a direct consequence of initiation by hydrogen atom generated during HME decomposition. Both biphenyl pyrolysis and hydrogenolysis mechanisms involve ipso hydrogen atom attack, followed by ejection of phenyl radical and the formation of benzene. Hydrogen atom is regenerated either through the phenylation of starting biphenyl or through the direct reaction of phenyl radical with H2. Both propagation reactions are very fast, leading to highly efficient chain transfer. Biaryl bond hydrogenolysis was found to be first-order in biphenyl and half-order in H2. Dimethylbiphenyls were found to undergo both demethylation and biaryl cleavage reactions during either neat hydrogenolysis or HME cohydrogenolysis. Cleavage of the much weaker aromatic methyl bond was found to be only slightly favored over biaryl cleavage in dimethylbiphenyl/HME cohydrogenolysis. The branching ratio for biaryl cleavage versus demethylation was also found to be sensitive to dimethylbiphenyl structure. The similar rates for biaryl cleavage and demethylation, as well as the structure sensitivity of the branching ratio, indicate the rate of formation and stability of the ipso hydrogen atom adduct are important in determining the rates of aromatic displacement reactions.

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Pyrolyse von Aromaten. 1. Mitteilung. Biphenyl

Cited by 10 publications

References 6 publications

A theoretical study on bond dissociation enthalpies of coal based model compounds

A theoretical study on bond dissociation enthalpies of coal based model compounds

Experimental and Theoretical Investigation on Three α,ω-Diarylalkane Pyrolysis

Hydrogen Transfer Induced Cleavage of Biaryl Bonds

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