Methyleneketenes and methylenecarbenes. XII. Thermal rearrangement of acetylene

1978 ◽  
Vol 31 (3) ◽  
pp. 579 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
GP Jackman
Keyword(s):  
Infrared Spectroscopy ◽  
Hydrogen Exchange ◽  
Spectral Studies ◽  
Intramolecular Rearrangement ◽  
Thermal Rearrangement ◽  
Mass Spectral ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis of 1,2,3,4-tetrafluoro-9-methoxy-9,10-dihydro- 9,10-ethenoanthracene[12-13C;10,12-D2], (600°) gives doubly labelled acetylene HC≡13CD. At temperatures of 700° and greater, the ethenoanthracene gives a mixture of HC≡13CD and DC≡13CH. Formation of the acetylene at 600° followed by pyrolysis at 850° confirmed that it is the free acetylene that undergoes intramolecular rearrangement: ����������������������������������� >700.����������������������������� HC≡13CD ↔ DC≡13CH The pattern of labelling in the acetylene was determined by allowing it to react with bromine and examining the resulting 1,1,2,2- tetrabromoethane by p.m.r. and infrared spectroscopy. Mass spectral studies on the tetrabromoethane showed that no significant intermolecular hydrogen exchange takes place up to 1050°.

Pyridyl- and Pyridylperoxy Radicals – A Matrix Isolation Study

2014 ◽  
Vol 67 (9) ◽  
pp. 1324 ◽  
Author(s):  
André Korte ◽  
Artur Mardyukov ◽  
Wolfram Sander
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectroscopy ◽  
Density Functional ◽  
Matrix Isolation ◽  
Ring Expansion ◽  
Peroxy Radicals ◽  
Functional Theory ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Good Agreement

The three isomeric pyridyl radicals 2a–c were synthesised using flash vacuum pyrolysis in combination with matrix isolation and characterised by infrared spectroscopy. The IR spectra are in good agreement with spectra calculated using density functional theory methods. The reaction of the pyridyl radicals 2 with molecular oxygen leads to the formation of the corresponding pyridylperoxy radicals 3a–c. The peroxy radicals 3 are photolabile, and irradiation results in syn–anti isomerisation of 3a and 3b and ring expansion of all three isomers of 3.

ChemInform Abstract: Detection by infrared Spectroscopy of Benzyne Formed by Flash Vacuum Pyrolysis and Trapped in an Argon Matrix.

1986 ◽  
Vol 17 (25) ◽  
Author(s):  
R. F. C. BROWN ◽  
N. R. BROWNE ◽  
K. J. COULSTON ◽  
L. B. DANEN ◽  
F. W. EASTWOOD ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Argon Matrix ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Conformational behaviour, photochemistry and flash vacuum pyrolysis of a 2-(1H-tetrazol-1-yl)thiophene

2017 ◽  
Vol 41 (24) ◽  
pp. 15581-15589 ◽  
Author(s):  
Maria I. L. Soares ◽  
Cláudio M. Nunes ◽  
Clara S. B. Gomes ◽  
Teresa M. V. D. Pinho e Melo ◽  
Rui Fausto
Keyword(s):  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Theoretical Calculations ◽  
Matrix Isolation ◽  
Flash Vacuum Pyrolysis ◽  
Fused Heterocycles ◽  
Vacuum Pyrolysis ◽  
Temperature Matrix ◽  
Photochemical Behaviour

The conformational and photochemical behaviour of a 2-(1H-tetrazol-1-yl)thiophene was studied using low-temperature matrix isolation infrared spectroscopy and theoretical calculations. FVP of 2-(1H-tetrazol-1-yl)thiophene afforded new thieno-fused heterocycles.

The biosynthesis of cyclopropane fatty acids. III. pH Dependence of methyl hydrogen exchange: gas chromatographic – mass spectral studies

1985 ◽  
Vol 63 (4) ◽  
pp. 971-974 ◽  
Author(s):  
Peter H. Buist ◽  
Judy M. Findlay
Keyword(s):  
Hydrogen Exchange ◽  
Ph Dependence ◽  
Total Activity ◽  
Spectral Studies ◽  
Deuterium Content ◽  
Cyclopropane Fatty Acid ◽  
Mass Spectral ◽  
Cyclopropane Fatty Acids ◽  
Decreasing Ph ◽  
Lactobacillic Acid

L-Methionine-methyl-d3 was administered to Lactobacillusplantarum and the deuterium content of the biosynthetic lactobacillic acid examined by gc–ms. By conducting the biosynthetic experiments in media of varying pH, it was shown that the production of d1-cyclopropane fatty acid increases with decreasing pH. Factors such as culture age and total activity of cyclopropane synthetase do not directly influence the extent of exchange.

The Pyrolysis of Butatrienone Precursors: 3,4-Diazatricyclo[5.2.1.02,6]deca-3,8-diene-endo-cis-2,6-dicarboxylic anhydride and Its 5,5-Diphenyl Derivative

1990 ◽  
Vol 43 (3) ◽  
pp. 549 ◽  
Author(s):  
MR Anderson ◽  
RFC Brown ◽  
NR Browne ◽  
FW Eastwood ◽  
GD Fallon ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Matrix Isolation ◽  
Argon Matrix ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis of the title anhydride (4) gave a poor yield of butatrienone , detected by argon matrix isolation infrared spectroscopy. Similar pyrolysis of the 5,5-diphenyl derivative (8) failed to give diphenylbutatrienone ; the red product (16) is considered to have been formed by dimerization of an intermediate 2H-indenylidenemethanone (15). The crystal structure of (16) has been determined.

Synthesis of Dimethylbutatrienone, (CH3)2C=C=C=C=O, by a Rearrangement-Fragmentation Process and by Direct Elimination

1991 ◽  
Vol 44 (1) ◽  
pp. 87 ◽  
Author(s):  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
MJ Irvine
Keyword(s):  
Infrared Spectroscopy ◽  
Acid Chloride ◽  
Fragmentation Pathway ◽  
Dienoic Acid ◽  
Fragmentation Process ◽  
Mixed Anhydride ◽  
Argon Matrix ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Derivatives Of

4-Methylpenta-1,2,3-trien-1-one ( dimethylbutatrienone , Me2C=C=C=C=O) was generated by flash vacuum pyrolysis of precursors derived from 4,4-dimethyl-2-oxotetrahydrofuran-3-ylideneacetic acid (6) and from 4-methylpenta-2,3-dienoic acid (14). Pyrolysis of the mixed trifluoroacetic anhydride and of the acid chloride of (6) and, in poorer yield, of (14) gave 4-methylpenta-1,2,3-trien-1-one which was detected by argon matrix infrared spectroscopy (Vmax 2224, 2216 cm-1) and by reaction with methanol to form methyl 4-methylpenta-2,3-dienoate. The fragmentation pathway for the derivatives of (6) was established by detection of the initially formed propadienone, 4,4-dimethyl-2-oxotetrahydrofuran-3-ylideneethenone, and also by pyrolysis of the trifluoroacetic mixed anhydride (7.L) and the acid chloride (8-L) of 4,4-dimethyl-2-oxotetrahydro(2-13C)furan-3-ylideneacetic acid. The argon matrix spectra of pyrolysates from (7-L) and (8-L) showed bands at 2182 and 2177cm-1 attributed to 4-methyl(1-13C)penta-1,2,3-trien-1-one. 4,4-Dimethyl-3-methylenedihydrofuran-2-one was prepared in 67% yield by flash vacuum pyrolysis of the acid (6).

Sulfonyl isocyanides RSO2NC

2017 ◽  
Author(s):  
Curt Wentrup ◽  
Horst Briehl
Keyword(s):  
Ir Spectrum ◽  
Reaction Conditions ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis (FVP) of 5-azido-1-aryltetrazoles results in triple N<sub>2</sub> elimination and formation of aryl isocyanides RNC, which rearrange in part to aroylnitriles RCN under the reaction conditions. Similar FVP of 5-azido-1-arenesulfonyltetrazoles generates a compound absorbing in the IR spectrum (77 K) at 2090 cm<sup>-1 </sup>and assigned the structure of arenesulfonyl isocyanide, ArSO<sub>2</sub>NC <b>11</b>. FVP at temperatures above 600 <sup>o</sup>C results in progressively more nitrile ArSO<sub>2</sub>CN <b>12</b>. Compound <b>11</b> also disappears on warming above -80 <sup>o</sup>C

Sulfonyl isocyanides RSO2NC

2017 ◽  
Author(s):  
Curt Wentrup ◽  
Horst Briehl
Keyword(s):  
Ir Spectrum ◽  
Reaction Conditions ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis (FVP) of 5-azido-1-aryltetrazoles results in triple N<sub>2</sub> elimination and formation of aryl isocyanides RNC, which rearrange in part to aroylnitriles RCN under the reaction conditions. Similar FVP of 5-azido-1-arenesulfonyltetrazoles generates a compound absorbing in the IR spectrum (77 K) at 2090 cm<sup>-1 </sup>and assigned the structure of arenesulfonyl isocyanide, ArSO<sub>2</sub>NC <b>11</b>. FVP at temperatures above 600 <sup>o</sup>C results in progressively more nitrile ArSO<sub>2</sub>CN <b>12</b>. Compound <b>11</b> also disappears on warming above -80 <sup>o</sup>C

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