1,3,5,7-Cyclooctatetraene Chemical Properties

Melting point:

-5--3 °C (lit.)

Boiling point:

142-143 °C (lit.)

Density 

0.925 g/mL at 25 °C (lit.)

refractive index 

n20/D 1.537(lit.)

Flash point:

72 °F

storage temp. 

-20°C

solubility 

Chloroform (Soluble), Methanol (Soluble)

form 

Liquid

Specific Gravity

0.943

color 

Turbid yellow to yellow-brown

Water Solubility 

Not miscible or difficult to mix in water.

Sensitive 

Light Sensitive

BRN 

2496800

Dielectric constant

2.46

Stability:

Stability Unstable - commercial product may be stabilized by the addition of a small amount of hydroquinone. May form explosive peroxides in storage. Do not distill to small volume. Readily forms explosive mixtures with air. Flammable. Incompatible with air, strong oxidizing agents.

LogP

3.080

CAS DataBase Reference

629-20-9(CAS DataBase Reference)

EPA Substance Registry System

1,3,5,7-Cyclooctatetraene (629-20-9)

Safety Information

Hazard Codes 

Xn,Xi,T

Risk Statements 

10-36/37/38-65-61

Safety Statements 

26-62-45-53

RIDADR 

UN 2358 3/PG 2

WGK Germany 

3

RTECS 

GY0175600

F 

8-10

TSCA 

Y

HazardClass 

3

PackingGroup 

II

HS Code 

29021900

MSDS

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1,3,5,7-Cyclooctatetraene Usage And Synthesis

Chemical Properties

1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as [8]annulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of its stoichiometric relationship to benzene, COT has been the subject of much research and some controversy.

Physical properties

Cyclooctatetraene (COT) is a poster child for nonaromatic molecules. An isomer of tub-shaped COT, with one of the ring double bonds changed from the usual cis form to a trans one, lies some 23 kcal/mol higher in energy.
Cyclooctatetraene is an 8p electron system and has a triplet ground state if the p electrons are delocalized. It is antiaromatic hence highly unstable and reactive. It adopts a non-planar boat conformation to attain stability with alternating single and double bonds and hence behaves like a polyolefin.
Cyclooctatetraene is a nonaromatic 4n π-conjugated system with a non-planar tub-shaped geometry and potential energy surfaces at the ground state.

Uses

Used in the synthesis of highly organic film for silicon surfaces to improve its chemical and physical properties. 1 Used in liquid state organic dye lasers. 2 Used as triplet state quencher to reduce dye blinking. 3

Uses

1,3,5,7-Cyclooctatetraene is used in the synthesis of highly organic film for silicon surfaces to improve its chemical and physical properties. It is also used in liquid state organic dye lasers, as triplet state quencher to reduce dye blinking.

Uses

COT may be functionalized by two side groups which can be used as active anode materials for rechargeable batteries. High capacity and voltage organic cathodes may be developed by using COT that can be fused with carbon molecules.

Definition

ChEBI: An antiaromatic annulene that is cyclooctane having four double bonds at positions 1, 3, 5 and 7.

Synthesis Reference(s)

Tetrahedron Letters, 21, p. 4791, 1980 DOI: 10.1016/0040-4039(80)80141-9

General Description

A colorless liquid. May irritate skin and eyes. Less dense than water and insoluble in water. Flash point 70°F. Vapors heavier than air. Used to make rubber.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

1,3,5,7-CYCLOOCTATETRAENE may react vigorously with strong oxidizing agents. May react exothermically with reducing agents to release hydrogen gas.

Health Hazard

Inhalation or contact with material may irritate or burn skin and eyes. Fire may produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

Purification Methods

Purify the triene by shaking 3mL with 20mL of 10% aqueous AgNO3 for 15minutes, then filtering off the AgNO3 complex which precipitates. The precipitate is dissolved in water and added to cold concentrated ammonia to regenerate the cyclooctatetraene which is fractionally distilled under vacuum onto molecular sieves and stored at 0o. It is passed through a dry alumina column before use [Broadley et al. J Chem Soc, Dalton Trans 373 1986]. [Beilstein 5 I 228, 5 IV 1331.]

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