Tetralin
{{chembox
|Watchedfields = changed
|verifiedrevid = 470604697
|Name = Tetralin
|ImageFile_Ref = {{chemboximage|correct|??}}
|ImageFile = Tetralin.svg
|ImageSize = 160px
|ImageAlt = Skeletal formula
|ImageFile1 = Tetralin-3D-balls.png
|ImageSize1 = 170px
|ImageAlt1 = Ball-and-stick model
|PIN = 1,2,3,4-Tetrahydronaphthalene
|OtherNames = 1,2,3,4-Tetrahydronaphthalene, Benzocyclohexane, NSC 77451, Tetrahydronaphthalene, Tetranap
|Section1={{Chembox Identifiers
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 35008
|SMILES = c1ccc2c(c1)CCCC2
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 8097
|PubChem = 8404
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = FT6XMI58YQ
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C14114
|InChI = 1/C10H12/c1-2-6-10-8-4-3-7-9(10)5-1/h1-2,5-6H,3-4,7-8H2
|InChIKey = CXWXQJXEFPUFDZ-UHFFFAOYAG
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C10H12/c1-2-6-10-8-4-3-7-9(10)5-1/h1-2,5-6H,3-4,7-8H2
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = CXWXQJXEFPUFDZ-UHFFFAOYSA-N
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 119-64-2
}}
|Section2={{Chembox Properties
|C=10 |H=12
|Appearance = colorless liquid
|Density = 0.970 g/cm3
|Solubility = Insoluble
|MeltingPtC = -35.8
|BoilingPtC = 206 to 208
|Viscosity = 2.02 cP at 25 °C{{cite journal|doi=10.1007/BF00514480|title=Density and viscosity of tetralin and trans-decalin|year=1989|last1=Gonçalves|first1=F. A.|last2=Hamano|first2=K.|last3=Sengers|first3=J. V.|journal=International Journal of Thermophysics|volume=10|issue=4|pages=845|bibcode=1989IJT....10..845G|s2cid=119843498}}
}}
|Section3={{Chembox Hazards
|ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/t1313.htm JT Baker MSDS]
|FlashPtC = 77
|AutoignitionPtC = 385
}}
}}
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.
Production
Tetralin is produced by the catalytic hydrogenation of naphthalene.{{Ullmann|first=Gerd|last=Collin|first2=Hartmut|last2=Höke|first3=Helmut|last3=Greim|title=Naphthalene and Hydronaphthalenes|year=2003|doi=10.1002/14356007.a17_001.pub2}}
Although nickel catalysts are traditionally employed, many variations have been evaluated.{{cite journal|doi=10.1007/BF00727949|title=Production of tetralin by the hydrogenation of naphthalene-containing fractions|year=1969|last1=Krichko|first1=A. A.|last2=Skvortsov|first2=D. V.|last3=Titova|first3=T. A.|last4=Filippov|first4=B. S.|last5=Dogadkina|first5=N. E.|journal=Chemistry and Technology of Fuels and Oils|volume=5|issue=1 |pages=18–22|bibcode=1969CTFO....5...18K |s2cid=95026822}} 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,{{cite book |author= Michael B. Smith |title= Organic Synthesis |publisher= Academic Press |year= 2011 |pages= 1209–1210 |edition= third |isbn= 9780124158849}}
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.{{cite journal|title=Hydrogen donor solvents in liquefaction of biomass: A review
|author=Isa, Khairuddin Md.; Abdullah, Tuan Amran Tuan; Md. Ali, Umi Fazara|journal=Renewable & Sustainable Energy Reviews|year=2018|volume=81(Part_1)|pages=1259–1268|doi=10.1016/j.rser.2017.04.006|bibcode=2018RSERv..81.1259I }}
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.[https://www.youtube.com/watch?v=cgawvTu9agA 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.{{rp|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.