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
Preferred IUPAC name 1,2,3,4-Tetrahydronaphthalene
Other names 1,2,3,4-Tetrahydronaphthalene, Benzocyclohexane, NSC 77451, Tetrahydronaphthalene, Tetranap
Identifiers
CAS Number	119-64-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:35008 Y
ChemSpider	8097 Y
ECHA InfoCard	100.003.946
KEGG	C14114 Y
PubChem CID	8404
UNII	FT6XMI58YQ Y
CompTox Dashboard (EPA)	DTXSID1026118
InChI InChI=1S/C10H12/c1-2-6-10-8-4-3-7-9(10)5-1/h1-2,5-6H,3-4,7-8H2 Y Key: CXWXQJXEFPUFDZ-UHFFFAOYSA-N Y InChI=1/C10H12/c1-2-6-10-8-4-3-7-9(10)5-1/h1-2,5-6H,3-4,7-8H2 Key: CXWXQJXEFPUFDZ-UHFFFAOYAG
SMILES c1ccc2c(c1)CCCC2
Properties
Chemical formula	C10H12
Molar mass	132.206 g·mol−1
Appearance	colorless liquid
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)
Solubility in water	Insoluble
Viscosity	2.02 cP at 25 °C[1]
Hazards
Flash point	77 °C (171 °F; 350 K)
Autoignition temperature	385 °C (725 °F; 658 K)
Safety data sheet (SDS)	JT Baker MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) 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 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]

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fast reactors as a secondary coolant to keep sodium seals around pump impellers solidified; however its use has been superseded by NaK.^[6]: 24:30

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

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. S2CID 119843498.
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. ISBN 978-3527306732.
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: 18–22. doi:10.1007/BF00727949. S2CID 95026822.
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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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.