Tetramethylbutane

{{Chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 401866579 | ImageFile = Tetramethylbutane skeletal.png | ImageFile_Ref = {{chemboximage|correct|??}} | ImageSize = 100 | ImageName = Skeletal formula of tetramethylbutane | ImageClass = skin-invert | ImageFile1 = Tetramethylbutane 3D 1.png | ImageFile1_Ref = {{chemboximage|correct|??}} | ImageSize1 = 100 | ImageName1 = Spacefill model of tetramethylbutane | ImageClass1 = bg-transparent | PIN = 2,2,3,3-Tetramethylbutane<ref>{{Cite web|title=Hexamethylethane - Compound Summary|url=https://pubchem.ncbi.nlm.nih.gov/compound/11675|work=PubChem Compound|publisher=National Center for Biotechnology Information|access-date=11 March 2012|location=USA|date=26 March 2005|at=Identification and Related Information}}</ref> |Section1={{Chembox Identifiers | CASNo = 594-82-1 | CASNo_Ref = {{cascite|correct|??}} | UNII_Ref = {{fdacite|correct|FDA}} | UNII = EB34RI15NY | PubChem = 11675 | ChemSpiderID = 11185 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | EINECS = 209-855-6 | UNNumber = 1325 | SMILES = CC(C)(C)C(C)(C)C | StdInChI = 1S/C8H18/c1-7(2,3)8(4,5)6/h1-6H3 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = OMMLUKLXGSRPHK-UHFFFAOYSA-N | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} }} |Section2={{Chembox Properties | C=8 | H=18 | Appearance = White, opaque, waxy crystals | Odor = Odorless | MeltingPtK = 371 to 377 | BoilingPtK = 379.1 to 380.1 | HenryConstant = 2.9 nmol Pa⁻¹ kg⁻¹ }} |Section3={{Chembox Thermochemistry | DeltaHf = −270.3 – −267.9 kJ mol⁻¹ | DeltaHc = −5.4526 – −5.4504 MJ mol⁻¹ | Entropy = 273.76 J K⁻¹ mol⁻¹ | HeatCapacity = 232.2 J K⁻¹ mol⁻¹ (at 2.8 °C) }} |Section4={{Chembox Hazards | GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|228|304|315|336|410}} | PPhrases = {{P-phrases|210|240|241|261|264|271|273|280|301+310|302+352|304+340|312|321|331|332+313|362|370+378|391|403+233|405|501}} | FlashPtC = 4 | ExploLimits = 1–?% }} |Section5={{Chembox Related | OtherFunction_label = alkanes | OtherFunction = {{Unbulleted list|Neopentane|2,2-Dimethylbutane|2,3-Dimethylbutane|Triptane|Tetraethylmethane|2,2,4-Trimethylpentane|2,3,3-Trimethylpentane|2,3,4-Trimethylpentane|Tetra-''tert''-butylmethane}} }} }}

'''Tetramethylbutane''', sometimes called '''hexamethylethane''', is a hydrocarbon with formula C₈H₁₈ or (H₃C-)₃C-C(-CH₃)₃. It is the most heavily branched and most compact of the octane isomers, the only one with a butane (C4) backbone. Because of its highly symmetrical structure, it has a very high melting point and a short liquid range; in fact, it is the smallest saturated acyclic hydrocarbon that appears as a solid at a room temperature of 25&nbsp;°C. (Among cyclic hydrocarbons, cubane, C₈H₈, norbornane, C₇H₁₂ and norbornene, C₇H₁₀ are even smaller and are also solid at room temperature.) It is also the most stable C₈H₁₈ isomer, with a heat of formation {{convert|4.18|kcal/mol|kJ/mol|abbr=on}} lower than that of ''n''-octane, a fact that has been attributed to stabilizing dispersive interactions (electron correlation) between the methyl groups (protobranching).<ref>{{Cite journal|last1=Joyce|first1=Justin P.|last2=Shores|first2=Matthew P.|last3=Rappè|first3=Anthony K.|date=2020-07-29|title=Protobranching as repulsion-induced attraction: a prototype for geminal stabilization|url=https://pubs.rsc.org/en/content/articlelanding/2020/cp/d0cp02193h|journal=Physical Chemistry Chemical Physics|language=en|volume=22|issue=29|pages=16998–17006|doi=10.1039/D0CP02193H|pmid=32676632 |bibcode=2020PCCP...2216998J |s2cid=220606477 |issn=1463-9084|url-access=subscription}}</ref>

The compound can be obtained from ethyl bromide, ''tert''-butyl bromide, and magnesium metal in the presence of manganese(II) ions. Despite conditions amenable to the formation of a Grignard reagent, organomagnesium compounds are believed not to be the active species. Instead, they transmetalate to organomanganese compounds, which then decompose to ''tert''-butyl radicals, which dimerize.<ref name="KHARASCH">{{cite journal |author1=M. S. KHARASCH |author2=J. W. HANCOCK |author3=W. NUDENBERG |author4=P. O. TAWNEY | year = 1956 | title = Factors Influencing the Course and Mechanism of Grignard Reactions. XXII. The Reaction of Grignard Reagents with Alkyl Halides and Ketones in the Presence of Manganous Salts | journal = Journal of Organic Chemistry | volume = 21 | issue = 3 | pages = 322–327 | doi=10.1021/jo01109a016}}</ref>

The full IUPAC name of the compound is '''2,2,3,3-tetramethylbutane''', but the numbers are superfluous in this case because there is no other possible arrangement of "tetramethylbutane".

==References== {{Reflist}}

Category:Alkanes