27041-32-3

Basic information

• Product Name: 5-ethenylidenecyclopenta-1,3-diene
• Synonyms: 1,3-Cyclopentadiene, 5-ethenylidene-
• CAS NO: 27041-32-3
• Molecular Formula: C₇H₆
• Molecular Weight: 90.1225
• Mol File: 27041-32-3.mol
• Article Data: 5

Chemical Properties

• Boiling Point: 149.7°C at 760 mmHg
• Flash Point: 18°C
• Density: 0.84g/cm³
• Vapor Pressure: 5.06mmHg at 25°C
• Refractive Index: 1.508
• CAS DataBase Reference: 5-ethenylidenecyclopenta-1,3-diene(CAS DataBase Reference)
• NIST Chemistry Reference: 5-ethenylidenecyclopenta-1,3-diene(27041-32-3)
• EPA Substance Registry System: 5-ethenylidenecyclopenta-1,3-diene(27041-32-3)

Safety Data

• Hazardous Substances Data: 27041-32-3(Hazardous Substances Data)

Upstream product

• 13426-49-8 7-Acetoxynorbornadien 
• 3469-06-5 benzocyclobutenone 
• 18039-42-4 5-Phenyl-1H-tetrazole 
• 13426-49-8 7-acetoxynorbornadiene 
• 96452-68-5 Spirohepta-2,5-dien-7,7'-<1,3,5>cycloheptatrien> 

Relevant articles and documents

Improved synthesis of benzocyclobutenone by flash vacuum pyrolysis

Flash vacuum pyrolysis of o-toluoyl chloride at 780 °C under 0.5 mmHg afforded benzocyclobutenone in higher yield (80%) than previously reported one (28 %).

1,2,4,6-CYCLOHEPTATETRAENE: THE KEY INTERMEDIATE IN ARYLCARBENE INTERCONVERSIONS AND RELATED C7H6 REARRANGEMENTS

Thermolysis or photolysis of phenyldiazomethane (2) produces phenylmethylene (3), which ring-expands to give 1,2,4,6-cycloheptatetraene (6).Spectroscopic and chemical evidence rule out bicyclo(4.1.0)hepta-2,4,6-triene (4), cycloheptatrienylidene (5), and bicyclo(3.2.0)hepta-1,3,6-triene (11) intermediates.The strained allene in cycloheptatetraene (6) exhibits infrared absorption at 1824 and 1816 cm-1.Deuterium substitution produces the expected 10-cm-1 shift in the allene absorption.Fluorine or chlorine substitution substantially enhances the allene absorption intensity.Deuterium labeling studies reveal that the intramolecular chemistry of cycloheptatetraene (6) involves reversible thermal or photochemical equilibriation with phenylmethylene (3).The intermolecular chemistry of 6 involves dimerization.At temperatures as low as 10 K, 6 forms a labile (2+2) dimer,7, which undergoes thermally allowed, electrocyclic ring opening to give heptafulvalene (8) upon warming to room temperature.The rearrangements of 7-acetoxynorbornadiene (9), 2-diazobicyclo(3.2.0)hepta-3,6-diene (31), and 8-diazobicyclo(2.2.2)octa-2,5-dien-7-one (33) all involve cycloheptatetraene (6) intermediates.

Carbene Reactions, XIV. - Generation of Cycloheptatrienylidene by Vapor Phase Thermolysis of C7H7-Acetates

Gas phase thermolysis at 450 deg C of 7-acetoxynorbornadiene (1) or of 7-acetoxycycloheptatriene (2) yielded acetic acid and heptafulvalene (4) indicative of the intermediate formation of cycloheptatrienylidene (3).The latter rearranged to fulveneallene (8) on thermolysis at 600 deg C.The elimination of acetic acid could involve a tropylium/acetate-ion pair since ionic processes dominate in the similar elimination of acetic acid from the tricyclic acetate 20.