20679-59-8

Basic information

• Product Name: 5-methylidenecyclohexa-1,3-diene
• Synonyms: 5-Methylene 1,3-cyclohexadiene; 5-Methylene-1,3-cyclohexadiene
• CAS NO: 20679-59-8
• Molecular Formula: C₇H₈
• Molecular Weight: 92.1384
• Mol File: 20679-59-8.mol
• Article Data: 4

Chemical Properties

• Boiling Point: 123°C at 760 mmHg
• Flash Point: 6.2°C
• Density: 0.86g/cm³
• Vapor Pressure: 16.4mmHg at 25°C
• Refractive Index: 1.505
• CAS DataBase Reference: 5-methylidenecyclohexa-1,3-diene(CAS DataBase Reference)
• NIST Chemistry Reference: 5-methylidenecyclohexa-1,3-diene(20679-59-8)
• EPA Substance Registry System: 5-methylidenecyclohexa-1,3-diene(20679-59-8)

Safety Data

• Hazardous Substances Data: 20679-59-8(Hazardous Substances Data)

Upstream product

• 67254-49-3 5-methylenebicyclo<2.2.0>hex-2-ene 
• 69961-23-5 cis-1,1-dibromo-2-(1,3-butadienyl)cyclopropane 
• 108-88-3 toluene 
• 65283-95-6 5-Methylenbicyclo<2.2.1>hept-2-en-7-on 
• 90534-57-9 Kohlensaeure-methyl-<1,4-cyclohexadien-1-ylmethyl>-ester 
• 539-30-0 benzyl ethyl ether cation radical 
• 104-51-8 1-butylbenzene 

Downstream Products

• 3071-34-9 benzyl hydroperoxide 
• 80106-14-5 (1-Methyl-cyclohexa-2,4-dienylmethyl)-benzene 
• 80106-13-4 (4-Methylene-cyclohex-2-enylmethyl)-benzene 
• 74502-19-5 1-methyl-5-benzyl-1,3-cyclohexadiene 
• 80106-16-7 (3-Methyl-cyclohexa-2,4-dienylmethyl)-benzene 
• 80106-15-6 (1-Methyl-cyclohexa-2,5-dienylmethyl)-benzene 
• 103-29-7 1,1'-(1,2-ethanediyl)bisbenzene 

Relevant articles and documents

REGIOSPEZIFISCHES UMLAGERUNGSVERHALTEN BUTADIENYL- UND VINYLSUBSTITUIERTER CYCLOPRPILYDENE

The reaction of the mono- and bis-dibromocarbene adducts of trans- and cis-hexatriene with methyllithium proceed regiospecifically.The results are supported by labelling (12C > 99.95percent) experiments.

The stepwise nature of the γ-hydrogen rearrangement in unsaturated ions

The mechanism of acetaldehyde elimination from the benzyl ethyl ether cation radical (1) yielding C7H8?+ ions is re-examined. A distonic ion intermediate (2) pertinent to a stepwise route is generated independently by dissociative ionization of 3-methyl-2,4-dioxaspiro[5.5]undeca-8,10-diene and by reaction of the methylenecyclohexa-2,4-diene cation radical with acetaldehyde. Metastable 1 and 2 differ in the kinetic energy released upon dissociation (Tav=7.0 and 1.1 kJ mol-1, respectively), indicating an energy barrier to the isomerization 1 → 2. During low-energy dissociation of 2 another C7H8?+ isomer, probably the more stable toluene cation radical, is also formed. This apparently takes place in an ion-molecule complex with acetaldehyde via reversible hydrogen transfer involving the acetaldehyde oxygen atom and represents an entropy bottleneck of the elimination. These competing second steps should produce D/H and the 18O/16O isotope effects in addition to the D/H effect of the first step 1 → 2, accounting for the observations by Bowie, Derrick, et al. attributed to a concerted mechanism; we believe this to be the first case involving this mechanism for a double isotope effect in a stepwise reaction. The kinetic energy release data, intermediate preparation and dissociation, and product characterization by collisionally activated dissociation spectra support a stepwise mechanism.

Absorption Spectra and Photochemical Rearrangements of Alkyl- and Dialkylbenzene Cations in Solid Argon

Matrix photoionization of alkyl- and dialkylbenzenes produced and trapped the parent radical cations.Irradiation in the visible parent cation absorption induced α-H transfer to the cation ring to give substituted methylenecyclohexadiene cations.The ease of 1,3-hydrogen transfer in these experiments suggests that this may be an important rearrangement in gaseous alkylbenzene cations.Subsequent ultraviolet photolysis of these samples produced substituted styrene cations.