Detection by infrared spectroscopy of benzyne formed by flash vacuum pyrolysis and trapped in an argon matrix

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.

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

Australian Journal of Chemistry ◽

10.1071/ch9910087 ◽

1991 ◽

Vol 44 (1) ◽

pp. 87 ◽

Cited By ~ 6

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).

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Pyridyl- and Pyridylperoxy Radicals – A Matrix Isolation Study

Australian Journal of Chemistry ◽

10.1071/ch14149 ◽

2014 ◽

Vol 67 (9) ◽

pp. 1324 ◽

Cited By ~ 10

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.

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Detection by infrared spectroscopy of benzyne formed byflash vacuum pyrolysis and trapped in an argon matrix

Tetrahedron Letters ◽

10.1016/s0040-4039(86)80052-1 ◽

1986 ◽

Vol 27 (9) ◽

pp. 1075-1078 ◽

Cited By ~ 18

Author(s):

Roger F.C. Brown ◽

Neil R. Browne ◽

Karen J. Coulston ◽

Louisa B. Danen ◽

Frank W. Eastwood ◽

...

Keyword(s):

Infrared Spectroscopy ◽

Argon Matrix ◽

Vacuum Pyrolysis

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

New Journal of Chemistry ◽

10.1039/c7nj02775c ◽

2017 ◽

Vol 41 (24) ◽

pp. 15581-15589 ◽

Cited By ~ 2

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.

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Cyclopentadienylideneethenone: Pyrolytic Generation and Argon Matrix Infrared Spectroscopic Study

Australian Journal of Chemistry ◽

10.1071/ch9891321 ◽

1989 ◽

Vol 42 (8) ◽

pp. 1321 ◽

Cited By ~ 15

Author(s):

RFC Brown ◽

NR Browne ◽

KJ Coulston ◽

FW Eastwood ◽

MJ Irvine ◽

...

Keyword(s):

Carbonyl Group ◽

Alder Reaction ◽

Infrared Spectroscopic Study ◽

Meldrum's Acid ◽

Meldrum’S Acid ◽

Argon Matrix ◽

Flash Vacuum Pyrolysis ◽

Matrix Isolation Spectroscopy ◽

Vacuum Pyrolysis ◽

Argon Matrices

Two previously reported pyrolytic precursors for cyclopentadienylideneethenone (4) and benzyne produced two strong infrared bands attributable to ketene type compounds when their pyrolysates were examined by argon matrix isolation spectroscopy. To determine which band should be assigned to (4), four new precursors for (4) and benzyne and two analogues labelled with 13C at the carbonyl group have been synthesized. Precursors (8) and (14) are respectively a caged system and a bridged ,system bearing a mixed anhydride with trifluoroacetic acid. Flash vacuum pyrolysis of (8) and (14) at 600-700 with trapping at 77 K gave pyrolysates which contained biphenylene. Pyrolysis of (8) and (14) at 600-700�; in a stream of argon followed by deposition as an argon matrix at about 10 K showed that both produced a pyrolysate absorbing at 2089 cm-1 assigned to (4). Precursors (24) and (25) and the previously reported (18) and (27) are Meldrum's acid derivatives designed to yield the hypothetical cyclopentadienylidene Meldrum's acid (19) by cage fission or retro-Diels-Alder reaction. They all gave their biphenylene on flash vacuum pyrolysis at 600-700 � and their pyrolysates in argon matrices showed absorption both at 2089 cm-1 due to (4) and at 2225 cm-1 due to an unidentified ketene. The frequency shift resulting from substitution of 13C in the carbonyl group (52 cm-l) is in accordance with the assignment of the 2089 cm-1 band to (4). The pyrolysates from precursors 8a), (14), (18a), (25)and (27) were allowed to react with methanol and the resulting mixtures were hydrogenated. In all cases methyl cyclopentylacetate was obtained.

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Methyleneketenes and methylenecarbenes. XII. Thermal rearrangement of acetylene

Australian Journal of Chemistry ◽

10.1071/ch9780579 ◽

1978 ◽

Vol 31 (3) ◽

pp. 579 ◽

Cited By ~ 28

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°.

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Sulfonyl isocyanides RSO2NC

10.26434/chemrxiv.5722528.v1 ◽

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 N2 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-1 and assigned the structure of arenesulfonyl isocyanide, ArSO2NC 11. FVP at temperatures above 600 oC results in progressively more nitrile ArSO2CN 12. Compound 11 also disappears on warming above -80 oC

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Sulfonyl isocyanides RSO2NC

10.26434/chemrxiv.5722528 ◽

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 N2 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-1 and assigned the structure of arenesulfonyl isocyanide, ArSO2NC 11. FVP at temperatures above 600 oC results in progressively more nitrile ArSO2CN 12. Compound 11 also disappears on warming above -80 oC

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