Tetralin

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Tetralin
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Template:Longitem Template:Chembox Elements/molecular formula
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Appearance colorless liquid
Density 0.970 g/cm3
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Viscosity 2.02 cP at 25 °C[1]
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Tetralin (1,2,3,4-tetrahydronaphthalene) is a hydrocarbon having the chemical formula C10H12. It is a partially hydrogenated derivative of naphthalene. It is a colorless liquid that is used as a hydrogen-donor solvent.[2]

Production

Tetralin is produced by the catalytic hydrogenation of naphthalene.[2]

File:Tetralin synthesis 01.svg

Although nickel catalysts are traditionally employed, many variations have been evaluated.[3] Over-hydrogenation converts tetralin into decahydronaphthalene (decalin). Rarely encountered is dihydronaphthalene (dialin).

Laboratory methods

In a classic named reaction called the Darzens tetralin synthesis, named for Auguste Georges Darzens (1926), derivatives can be prepared by intramolecular electrophilic aromatic substitution reaction of a 1-aryl-pent-4-ene using concentrated sulfuric acid,[4]

File:Darzens Synthesis of Tetralin Derivatives.svg
Darzens synthesis of tetralin derivatives

Uses

Tetralin is used as a hydrogen-donor solvent, for example in coal liquifaction. It functions as a source of H2, which is transferred to the coal. The partially hydrogenated coal is more soluble.[5][2]

It has been used in sodium-cooled fast reactors as a secondary coolant to keep sodium seals around pump impellers solidified; however its use has been superseded by NaK.[6]Template:Rp

It is also used for the laboratory synthesis of hydrogen bromide:

C10H12 + 4 Br2 → C10H8Br4 + 4 HBr

The facility of this reaction is in part a consequence of the moderated strength of the benzylic C-H bonds.

Safety

LD50 (rats, oral) is 2.68 g/kg. Tetralin induces methemoglobinemia.[2]

References

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  6. US Atomic Energy Commission (1961) SRE Core Recovery Remediation method after a failure in the moderator cans due to a crack in the secondary coolant tubes in the SRE, Spring 1959. This caused a leak of Tetralin into the reactor.

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