Tetralin

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]

Tetralin
Names
IUPAC name
1,2,3,4-tetrahydronaphthalene
Other names
1,2,3,4-Tetrahydronaphthalene, Benzocyclohexane, NSC 77451, Tetrahydronaphthalene, Tetranap
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.946
KEGG
UNII
Properties
C10H12
Molar mass 132.206 g·mol−1
Appearance colorless liquid with an odor similar to naphthalene
Density 0.970 g/cm3
Melting point −35.8 °C (−32.4 °F; 237.3 K)
Boiling point 206 to 208 °C (403 to 406 °F; 479 to 481 K)
Insoluble
Viscosity 2.02 cP at 25 °C[1]
Hazards
Safety data sheet JT Baker MSDS
Flash point 77 °C (171 °F; 350 K)
385 °C (725 °F; 658 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Production

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

Although nickel catalysts are traditionally employed, many variations have been evaluated.[3] Over hydrogenation converts tetralin into octahydronaphthalene (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-4-pentene using concentrated sulfuric acid,[4]

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.

It is also used for the laboratory synthesis of HBr:

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
  1. Gonçalves, F. A.; Hamano, K.; Sengers, J. V. (1989). "Density and viscosity of tetralin and trans-decalin". International Journal of Thermophysics. 10 (4): 845. Bibcode:1989IJT....10..845G. doi:10.1007/BF00514480.
  2. Collin, Gerd; Höke, Hartmut; Greim, Helmut (2003). "Naphthalene and Hydronaphthalenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_001.pub2.
  3. Krichko, A. A.; Skvortsov, D. V.; Titova, T. A.; Filippov, B. S.; Dogadkina, N. E. (1969). "Production of tetralin by the hydrogenation of naphthalene-containing fractions". Chemistry and Technology of Fuels and Oils. 5: 18. doi:10.1007/BF00727949.
  4. Michael B. Smith (2011). Organic Synthesis (third ed.). Academic Press. pp. 1209–1210. ISBN 9780124158849.
  5. Isa, Khairuddin Md.; Abdullah, Tuan Amran Tuan; Md. Ali, Umi Fazara (2018). "Hydrogen donor solvents in liquefaction of biomass: A review". Renewable & Sustainable Energy Reviews. 81(Part_1): 1259-1268. doi:10.1016/j.rser.2017.04.006.CS1 maint: multiple names: authors list (link)
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