544-25-2

Usage

Chemical Properties

Cycloheptatriene is a clear yellow to brownish liquid. Insoluble in water and less dense than water. Vapors heavier than air. Inhalation of high concentrations may have a narcotic effect. It is a ligand in organometallic chemistry and as a building block in organic synthesis. Cycloheptatriene is not aromatic, as reflected by the nonplanarity of the methylene bridge with respect to the other atoms.

Uses

1,3,5-Cycloheptatriene functions as a ligand in organometallic chemistry and also as a building block in organic synthetic processes. 1,3,5-Cycloheptatriene is applied in cycloheptatrienyl transition zirconium complexes formation and in other organic complex formation processes.

Definition

ChEBI: A cycloheptatriene with unsaturation at positions 1, 3 and 5.

Synthesis Reference(s)

Journal of the American Chemical Society, 81, p. 5009, 1959 DOI: 10.1021/ja01527a075Tetrahedron, 21, p. 1673, 1965 DOI: 10.1016/S0040-4020(01)98637-5

General Description

A colorless liquid. Insoluble in water and less dense than water. Flash point 35°F. Vapors heavier than air. Inhalation of high concentrations may have a narcotic effect. Used to make other chemicals.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

Cycloheptatriene may react vigorously with strong oxidizing agents. May react exothermically with reducing agents to release hydrogen gas. In the presence of various catalysts (such as acids) or initiators, may undergo exothermic addition polymerization reactions.

Health Hazard

TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Inhalation or contact with some of these materials will irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

Fire Hazard

HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Safety Profile

Poison by ingestion and skin contact. Mutation data reported. A very dangerous fire hazard when exposed to heat, flame, or oxidzers. Potentially violent reaction with nitrogen monoxide. Whenheated to decomposition it emits acrid smoke and fumes.

Purification Methods

Wash the triene with alkali, then fractionally distil it. Store it under N2 or Ar as it resinifies in air. [Dryden J Am Chem Soc 76 2814 1954, Kohler et al. J Am Chem Soc 61 1057 1939, Beilstein 5 IV 280.]

InChI:InChI=1/C7H8/c1-2-4-6-7-5-3-1/h1-6H,7H2

Upstream product

• 186581-53-3 diazomethane 
• 71-43-2 benzene 
• 110-86-1 pyridine 
• 13259-28-4 bicyiclo<3.2.0>hept-2-en-6-ol 
• 124-63-0 methanesulfonyl chloride 
• 876938-53-3 Cyclohepta-1,3-diene 
• 823-69-8 7,7-dichloro-bicyclo[4.1.0]heptane 
• 291-64-5 cycloheptane 
• 14515-09-4 norcaradiene 
• 121-46-0 bicyclo[2.2.1]hepta-2,5-diene 
• 53267-65-5 toluene-4-sulfonic acid cyclohexa-2,5-dienylmethyl ester 
• 121-46-0 bicyclo[2.2.1]hepta-2,5-diene 
• 120-29-6 3-tropanol 
• 502-42-1 cycloheptanone 

Downstream Products

• 533-75-5 2-hydroxy-2,4,6-cycloheptatrien-1-one 
• 86605-42-7 8,8-dichloro-bicyclo[5.1.0]octa-2,4-diene 
• 27081-10-3 tropylium tetrafluoroborate 
• 25230-72-2 tropylium perchlorate 
• 95315-89-2 5-Butyl-7-benzyl-cycloheptadien-(1.3) 
• 1541-11-3 7-phenylcycloheptatriene 
• 49586-03-0 C₁₀H₈Cl₆ 
• 49586-03-0 C₁₀H₈Cl₆ 
• 51290-66-5 8-p-tolyl-7-oxa-8-aza-bicyclo[4.2.1]nona-2,4-diene 
• 30267-38-0 7-(2,5-Diphenyl-cyclopenta-2,4-dienyl)-cyclohepta-1,3,5-triene 
• 30119-69-8 2',3'-Diphenyl-inden-1-spiro-8'-bicyclo<5.1.0>octadien-(2,5) 
• 21703-97-9 7-(4-chloro-phenyl)-6-oxa-7-aza-bicyclo[3.2.2]non-8-ene 
• 51290-67-6 8-(4-nitro-phenyl)-7-oxa-8-aza-bicyclo[4.2.1]nona-2,4-diene 
• 13975-99-0 7-<2.3.4.5-Tetraphenyl-cyclopentadien-(2.4)-yl-(1)>-cycloheptatrien-(1.3.5) 

Relevant academic research and scientific papers

Pulse Radiolysis Study of the Cycloheptatriene Triplet State: Lifetime, Relaxation, and Nonvertical Excitation

The triplet state of cycloheptatriene (CHT) has been produced by pulse radiolysis in toluene.Its lifetime of 6 +/- 1 μs is considerably longer than for acyclic trienes, ca. 300 ns, despite a smaller energy gap between the relaxed T1 and S0 surfaces.It is proposed that relaxation is from the boatlike spectroscopic state to an approximately planar species within which spin-orbit coupling factors are minimized.Plots of log ket vs. donor triplet energy for endothermic triplet energy transfer to both CHT and the acyclic neo-alloocimene (NA) show that, whereas the latter is close to being a vertical acceptor of triplet energy, CHT exhibits clear "nonvertical" character.In this respect, NA and CHT mimic trans- and cis-stilbene, respectively.It would appear that, for olefinic systems, established "nonvertical" behavior is currently restricted to nonplanar ? systems, and the possibility is raised that such behavior may, at least in part, reflect higher vibrational level densities in such systems.

Formation of charge-transfer complexes based on a tropylium cation and 2,6-helic[6]arenes: a visible redox stimulus-responsive process

Charge-transfer (CT) complexes formed from 2,6-helic[6]arene hosts and a tropylium cation are described in detail. In particular, it was found that the binding and release processes of the guest in the complexes could be efficiently controlled by a redox stimulus, and the responsive process could be visually observed by the color change of the solution. To our knowledge, this represents the first visible redox stimulus-responsive host-guest system formed from the tropylium cation.

Synthesis of 1,2,3,4,5,6,7-Heptasubstituted Cycloheptatrienes through Cycloaddition Reactions of Substituted Cyclopentadienones

Two schemes for synthesizing heptasubstituted cycloheptatrienes with various substituents in the ring are suggested. The first method is based on cycloaddition of 2,5-dimethoxycarbonyl-3,4-diphenylcyclopentadienone with substituted cyclopropenes and allows cycloheptatrienes containing two or three electron-withdrawing substituents in the molecule to be obtained. The second method employs a cascade reaction between a substituted cyclopentadienone and appropriate vinyldiazoacetates. It allows the number of electron-withdrawing substituents to be increased to five. In all cases, heptasubstituted cycloheptatrienes are formed as just one of the possible isomers.

Synthesis and characterization of manganese triple-decker complexes

The use of the highly sterically demanding CpBIG ligand (CpBIG = C5(4-nBuC6H4)5) and white phosphorus (P4) enables the synthesis of new P-rich derivatives of the rare Pn ligand complexes of manganese. The obtained complexes, [{CpBIGMn}2(μ,η5:5-P5)] (2) and [{CpBIGMn}2(μ,η2:2-P2)2] (3), exhibit the highest number of P atoms in this class of manganese compounds identified by X-ray structure analyses. The EPR spectrum of the 29 VE triple-decker complex 2 shows one unpaired electron coupling with two 5/2 spin Mn nuclei.

Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement

Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.

Generation of methylene by the liquid phase oxidation of isobutene with nitrous oxide

The application of nitrous oxide as an alternative oxidant provides new opportunities for selective oxidation of olefins. Here, we studied for the first time the thermal oxidation of isobutene with N2O in the liquid phase. The study revealed that the oxidation proceeds via 1,3-dipolar cycloaddition of N2O to the C[dbnd]C bond by two routes forming unstable 4,5-dihydro-[1,2,3]-oxadiazole intermediates. The main route (the contribution of 91%) includes the addition of the N2O oxygen to the second carbon atom in olefin. In this case, the oxadiazole decomposes with the C–C bond cleavage yielding acetone, methylene (:CH2), and N2. The methylene then readily reacts with isobutene and benzene (solvent). The minor route involves the addition of the N2O oxygen to the first carbon atom and the oxadiazole decomposition with a hydrogen shift leading to isobutanal and N2. The main distinctive feature of the studied reaction is the formation of methylene in high yield.

Gold(I) Carbenoids: On-Demand Access to Gold(I) Carbenes in Solution

Chloromethylgold(I) complexes of phosphine, phosphite, and N-heterocyclic carbene ligands are easily synthesized by reaction of trimethylsilyldiazomethane with the corresponding gold chloride precursors. Activation of these gold(I) carbenoids with a variety of chloride scavengers promotes reactivity typical of metallocarbenes in solution, namely homocoupling to ethylene, olefin cyclopropanation, and Buchner ring expansion of benzene.

Comparison of enzymatic and acid hydrolysis of bound flavor compounds in model system and grapes

Four synthesized terpenyl-β-D-glycopyranosides (geranyl, neryl, citronellyl, myrtenyl) were subjected to enzymatic (AR 2000, pH 5.5) and acid (citric buffer, pH 2.5) hydrolysis. Decrease of glycosides was measured by HPLC and the volatiles released - by comprehensive gas chromatography-mass spectrometry (GC x GC-ToF-MS). Enzymatic hydrolysis performed for 21 h yielded 100% degree of hydrolysis for all glycosides but citronellyl (97%). Degree of acid hydrolysis was highly dependent on type of aglycone and the conditions. The highest degree was achieved for geraniol, followed by citronellol and nerol. Myrtenylo-β-D-glycopyranoside was the most resistant glycoside to hydrolysis. Acid hydrolysis degree was also related to temperature/time combination, the highest being for 100 °C and 2 h. In a result of enzymatic hydrolysis 85-91% of total peak areas was terpene aglycone, whereas for acid hydrolysis the area of released terpene aglycone did not exceed 1.3% of total peak area indicating almost complete decomposition/transformation of terpenyl aglycone.

Synthesis, structure, and reactivity of a gold carbenoid complex that lacks heteroatom stabilization

Hydride abstraction from the neutral gold cycloheptatrienyl complex [(P)Au(η1-C7H7)] (P=P(tBu) 2(o-biphenyl)) with triphenylcarbenium tetrafluoroborate at -80 C led to the isolation of the cationic gold cycloheptatrienylidene complex [(P)Au(η1-C7H6)]+ BF 4- in 52 yield, which was characterized in solution and by single-crystal X-ray diffraction. This cycloheptatrienylidene complex represents the first example of a gold carbenoid complex that lacks conjugated heteroatom stabilization of the electron-deficient C1 carbon atom. The cycloheptatrienylidene ligand of this complex is reactive; it can be reduced by mild hydride donors, and converted to tropone in the presence of pyridine N-oxide. Hydride abstraction from the neutral gold cycloheptatrienyl complex 1 (P=P(tBu)2 (o-biphenyl)) with Ph3C+ BF 4- formed the cationic gold cycloheptatrienylidene complex 2, which was characterized by single-crystal X-ray diffraction. The cycloheptatrienylidene ligand of 2 is reactive; it can be reduced by mild hydride donors, and converted into tropone in the presence of pyridine N-oxide.

Dihydroazulene-buckminsterfullerene conjugates

The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has recently attracted interest as a molecular switch for molecular electronics. In this field, Buckminsterfullerene, C60, has been shown to be a useful anchoring group for adhering a molecular wire to an electrode. Here we have combined the two units with the overall aim to elucidate how C60 influences the DHA-VHF switching events. Efficient synthetic protocols for making covalently linked DHA-C60 conjugates were developed, using Prato, Sonogashira, Hay, and Cadiot-Chodkiewicz reactions. These syntheses provide as well a variety of potentially useful DHA and C60 building blocks for acetylenic scaffolding. The two units were separated by bridges of various lengths, such as oligo(phenyleneethynylene) (OPE2 and OPE3) wires. The distance of separation was found to influence strongly the light-induced ring-opening reaction of DHA to its corresponding VHF. Thus, C60 was found to significantly quench this conversion when situated closely to the DHA unit.