:Di-tert-butylcyclopentadiene
{{DISPLAYTITLE:Di-tert-butylcyclopentadiene}}
{{Chembox
| ImageFile = C5H4(tert-Bu)2.png
| ImageSize = 122 px
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|Section1={{Chembox Identifiers
| CASNo = 73046-16-9
| CASNo1 = 114987-03-0
| PubChem = 3599405
| ChemSpiderID = 2835281
| DTXSID = DTXSID70394029
| StdInChI=1S/C13H22/c1-12(2,3)10-7-8-11(9-10)13(4,5)6/h7-10H,1-6H3
| StdInChIKey = RADVPPBTEASJRZ-UHFFFAOYSA-N
| SMILES = CC(C)(C)C1C=CC(=C1)C(C)(C)C
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|Section2={{Chembox Properties
| C=13|H=22
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| Density =
| MeltingPt =
| BoilingPtC = 100–105
| BoilingPt_notes = 30 torr
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|Section3={{Chembox Hazards
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Di-tert-butylcyclopentadiene is an organic compound with the formula (Me3C)2C5H4, where Me = methyl. It is a colorless liquid that is soluble in organic solvents. The compound is the conjugate acid of the di-tert-butylcyclopentadienyl ligand, (Me3C)2C5H3−{{cite journal|doi=10.1002/047084289X.rn01866|title=1,3-Di-tert-butylcyclopentadiene|journal=Encyclopedia of Reagents for Organic Synthesis|year=2015|last1=Hyster|first1=Todd K.|pages=1–2|isbn=9780470842898}} (sometimes abbreviated Cp‡−). Two regioisomers of di-tert-butylcyclopentadiene exist, depending on the relative location of the double bonds.
Synthesis and reactions
Di-tert-butylcyclopentadiene is prepared by alkylation of cyclopentadiene with tert-butyl bromide under phase-transfer conditions.{{cite book|doi=10.1002/9781119477822.ch8|title=Synthesis of 1,3,5-Tri-tert-Butylcyclopenta-1,3-diene and Its Metal Complexes Na{1,2,4-(Me3C)3C5H2} and Mg{η5-1,2,4-(Me3C)3C5H2)2|year=2018|last1=Reiners|first1=Matthias|last2=Ehrlich|first2=Nico|last3=Walter|first3=Marc D.|series=Inorganic Syntheses|volume=37|page=199|s2cid=105376454 }}
It is the precursor to many metal complexes, such as the olefin polymerization catalyst ((Me3C)2C5H3)TiCl3.{{cite journal|doi=10.1021/OM980106R|title=Synthesis of Various Nonbridged Titanium(IV) Cyclopentadienyl−Aryloxy Complexes of the Type C{{prime|p}}Ti(OAr)X2 and Their Use in the Catalysis of Alkene Polymerization. Important Roles of Substituents on both Aryloxy and Cyclopentadienyl Groups|year=1998| last1=Nomura|first1=Kotohiro|last2=Naga|first2=Naofumi|last3=Miki|first3=Misao|last4=Yanagi|first4=Kazunori|last5=Imai|first5=Akio|journal=Organometallics|volume=17|issue=11|pages=2152–2154}}
The conjugate base of di-tert-butylcyclopentadiene reacts with a third equivalent of tert-butyl bromide to give (Me3C)3C5H3:
:(Me3C)2C5H4 + NaH → Na(Me3C)3C5H3 + H2
:Na(Me3C)2C5H3 + Me3CBr → (Me3C)3C5H3 + NaBr