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).

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

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.

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.

Methyleneketenes and methylenecarbenes. IV. Pyrolysis of 5-Heteroarylmethylene-2,2-dimethyl-l,3-dioxan-4,6-diones to give phenolic benzothiophens, benzofurans and indoles

1974 ◽  
Vol 27 (12) ◽  
pp. 2605 ◽  
Author(s):  
GJ Baxter ◽  
RFC Brown ◽  
GL McMullen
Keyword(s):  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Synthetic Sequence ◽  
Heterocyclic Aldehydes ◽  
Derivatives Of

The synthetic sequence leading from o-tolualdehyde to 2-naphthol1 has been applied to seven five membered heterocyclic aldehydes bearing adjacent methyl substituents. Flash vacuum pyrolysis of the corresponding 5-heteroarylmethylene-2,2-dimethyl-1,3-dioxan-4,6-diones gave hydroxy derivatives of the benzologous systems benzothiophene, benzofuran, dibenzofuran, indole and carbazole in 54-98% yield.

Hot-Tube Reactions of Dehydroabietic Acid with Ketene-Producing Reagents. Pyrolysis of the Acid Chloride and Symmetrical and Mixed Anhydride Derivatives of Dehydroabietic Acid

1973 ◽  
Vol 51 (19) ◽  
pp. 3236-3241 ◽  
Author(s):  
Ray F. Severson ◽  
Walter H. Schuller
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Acid Chloride ◽  
Acetyl Chloride ◽  
Dehydroabietic Acid ◽  
Mixed Anhydride ◽  
Temperature Range ◽  
Acid Isomerization ◽  
Derivatives Of ◽  
Isopropenyl Acetate

Dehydroabietic acid (1a) was reacted with diketene, acetic acid, acetic anhydride, isopropenyl acetate, acetyl chloride, and acetone on Vycor rod at 450 °C in a hot tube. Dehydroabietic anhydride (1b) and acetyl dehydroabietate (1c) were pyrolyzed at 450 °C and dehydroabietyl chloride (1d) was pyrolyzed over a temperature range of 290–500 °C. The major olefin products resulting from decarboxylation of the various derivatives were 19-norabieta-4,8,11,13-tetraene (2), 19-norabieta-4(18),8,11,13-tetraene (3), 19-norabieta-3,8,11,13-tetraene (4), and cis-1,10a-dimethyl-7-isopropyl-1,2,3,9,10,10a-hexahydrophenanthrene (5). High conversions to these compounds were obtained. In the presence of the ketene-producing reagents the olefins were oxidized to yield substantial amounts of retene (6), compounds 2 and 5 being the most readily dehydrogenated. The acid isomerization of 2, 3, 4, and 5 was studied using p-toluenesulfonic acid in toluene at 110 °C.

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

1986 ◽  
Vol 27 (9) ◽  
pp. 1075-1078 ◽  
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

Methyleneketenes and methylenecarbenes. III. Pyrolytic synthesis of arylacetylenes and their thermal rearrangements involving arylrnethylenecarbenes

1974 ◽  
Vol 27 (11) ◽  
pp. 2391 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
KJ Harrington ◽  
GL McMullen
Keyword(s):  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Thermal Rearrangements ◽  
Isopropylidene Malonate ◽  
Derivatives Of

Flash vacuum pyrolysis (550-600�) of 5-benzylidene derivatives of 2,2- dimethyl-1,3-dioxan-4,6-dione(isopropylidene malonate) gives phenylacetylenes bearing m- or p-substituents (H, Me, MeO, Cl, CN)in 64-98% yield. o-Methoxy- and o-phenyl-benzylidene derivatives give the arylacetylenes even at 420�. Arylacetylenes equilibrate with arylmethylenecarbenes, ArCH=C:, at 550-720�, as shown by labelling experiments using 13C and by the formation of products of interaction with o-substituents. Methylenebenzocyclobutene and o-tolylacetylene each form indene at 700-720�.

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.

Cyclopentadienylideneethenone: Pyrolytic Generation and Argon Matrix Infrared Spectroscopic Study

1989 ◽  
Vol 42 (8) ◽  
pp. 1321 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document