View source for Neopentane

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 406841269
| ImageFile = 2,2-dimethylpropane.png
| ImageFile_Ref = {{chemboximage|correct|??}}
| ImageSize = 100
| ImageName = Stereo, skeletal formula of neopentane
| ImageFile1 = Neopentane.PNG
| ImageFile1_Ref = {{Chemboximage|correct|??}}
| ImageSize1 = 160
| ImageName1 = Skeletal formula of neopentane with all implicit carbons shown, and all explicit hydrogens added
| ImageFileL2 = Neopentane-3D-balls.png
| ImageFileL2_Ref = {{Chemboximage|correct|??}}
| ImageNameL2 = Ball and stick model of neopentane
| ImageFileR2 = Neopentane-3D-vdW.png
| ImageFileR2_Ref = {{Chemboximage|correct|??}}
| ImageNameR2 = Spacefill model of neopentane
| PIN = 2,2-Dimethylpropane<ref name="IUPAC2013_652">{{cite book | title =  Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 652 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter }}</ref><!-- Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) -->
| OtherNames = Neopentane<br />Tetramethylmethane<ref>Aston, J.G.; Messerly, G.H., Heat Capacities and Entropies of Organic Compounds II. Thermal and Vapor Pressure Data for Tetramethylmethane from 13.22K to the Boiling Point. The Entropy from its Raman Spectrum, J. Am. Chem. Soc., 1936, 58, 2354.</ref>
|Section1={{Chembox Identifiers
| CASNo = 463-82-1
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 10041
| ChemSpiderID = 9646
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EINECS = 207-343-7
| MeSHName = neopentane
| ChEBI = 30358
| ChEBI_Ref = {{ebicite|correct|EBI}}
| Beilstein = 1730722
| Gmelin = 1850
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = M863R1J0BP
| UNNumber = 2044
| SMILES = CC(C)(C)C
| StdInChI = 1S/C5H12/c1-5(2,3)4/h1-4H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = CRSOQBOWXPBRES-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
|Section2={{Chembox Properties
| C=5 | H=12
| Appearance = Colorless gas
| Odor = Odorless
| Density =  3.255 kg/m<sup>3</sup> (gas, 9.5&nbsp;°C)<br/>601.172 kg/m<sup>3</sup> (liquid, 9.5&nbsp;°C)
| MeltingPtC = -16.5
| BoilingPtC = 9.5
| VaporPressure = 146 kPa (at 20&nbsp;°C)<ref>{{cite web| url = https://pubchem.ncbi.nlm.nih.gov/compound/neopentane#section=Vapor-Pressure |title = Neopentane {{!}} C5H12 - PubChem}}</ref>
| HenryConstant = 4.7 nmol Pa<sup>−1</sup> kg<sup>−1</sup>
}}
|Section3={{Chembox Thermochemistry
| DeltaHf = −168.5–−167.3 kJ mol<sup>−1</sup>
| DeltaHc = −3.51506–−3.51314 MJ mol<sup>−1</sup>
| Entropy = 217 J K<sup>−1</sup> mol<sup>−1</sup>
| HeatCapacity = 121.07–120.57 J K<sup>−1</sup> mol<sup>−1</sup>
}}
|Section4={{Chembox Hazards
| GHSPictograms = {{GHS02}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|220|411}}
| PPhrases = {{P-phrases|210|273|377|381|391|403|501}}
| NFPA-H = 1
| NFPA-F = 4
| NFPA-R = 0
}}
|Section5={{Chembox Related
| OtherFunction_label = alkanes
| OtherFunction = {{Unbulleted list|[[2,2-Dimethylbutane]]|[[2,3-Dimethylbutane]]|[[Triptane]]|[[Tetramethylbutane]]}}
| OtherCompounds = {{unbulleted list|[[Tetramethylsilane]]|[[Tetramethylgermane]]|[[Tetramethylstannane]]|[[Tetramethyllead|Tetramethylplumbane]]}}
}}
}}
'''Neopentane''', also called '''2,2-dimethylpropane''', is a double-branched-chain [[alkane]] with five [[carbon]] atoms.  Neopentane is a [[flammable]] [[gas]] at room [[temperature]] and [[pressure]] which can condense into a highly [[Volatility (chemistry)|volatile]] [[liquid]] on a cold day, in an ice bath, or when compressed to a higher pressure.

Neopentane is the simplest alkane with a [[quaternary carbon]], and has achiral [[tetrahedral symmetry]].  It is one of the three [[structural isomerism|structural isomers]] with the [[molecular formula]] C<sub>5</sub>H<sub>12</sub> ([[pentane]]s), the other two being [[pentane|''n''-pentane]] and [[isopentane]].  Out of these three, it is the only one to be a gas at standard conditions; the others are liquids.

It was first synthesized by Russian chemist {{Ill|Mikhail Lvov|ru|Львов, Михаил Дмитриевич}} in 1870.<ref>{{Cite book |url=https://books.google.com/books?id=UG4vAQAAMAAJ&pg=PA520 |title=Zeitschrift für Chemie |date=1870 |publisher=Quandt & Händel |language=de}}</ref>

==Nomenclature==
The traditional name neopentane, coined by [[William Odling]] in 1876,<ref>{{Cite book |url=https://books.google.com/books?id=JplJAQAAMAAJ&pg=PA209 |title=Philosophical Magazine |date=1876 |publisher=Taylor & Francis. |language=en}}</ref> was still retained in the 1993 [[International Union of Pure and Applied Chemistry|IUPAC]] recommendations,<ref>[http://www.acdlabs.com/iupac/nomenclature/93/r93_679.htm Table 19(a) Acyclic and monocyclic hydrocarbons. Parent hydrocarbons]</ref><ref name="panico">{{cite book | editor=Panico, R. | editor2= Powell, W. H.  | name-list-style= amp | title=A Guide to IUPAC Nomenclature of Organic Compounds 1993 | location=Oxford | publisher=Blackwell Science | year=1994 | isbn=978-0-632-03488-8}}
</ref> but is no longer recommended according to the 2013 recommendations.<ref name="IUPAC2013_652"/> The [[preferred IUPAC name]] is the systematic name 2,2-dimethylpropane, but the substituent numbers are superfluous because it is the only possible “dimethylpropane”.

[[Image:Neopentyl-group-2D-skeletal.png|thumb|100px|left|A neopentyl group attached to a generic group R.]]

A neopentyl [[substituent]], often symbolized by "Np", has the structure Me<sub>3</sub>C–CH<sub>2</sub>– for instance [[neopentyl alcohol]] (Me<sub>3</sub>CCH<sub>2</sub>OH or NpOH). As Np also symbolises the element [[neptunium]] (atomic number 93) one should use this abbreviation with care.

The obsolete name tetramethylmethane is also used, especially in older sources.<ref>{{Cite journal|last1=Whitmore|first1=Frank C.|last2=Fleming|first2=Geo. H.|date=1934-09-01|title=Preparation of Tetramethylmethane (Neopentane) and Determination of its Physical Constants1|journal=Journal of the American Chemical Society|volume=55|issue=9|pages=3803–3806|doi=10.1021/ja01336a058|issn=0002-7863}}</ref><ref>{{Cite journal|last=LaCoste|first=Lucien J. B.|date=1934-10-15|title=The Rotational Wave Equation of Tetramethylmethane for Zero Potential and a Generalization|journal=Physical Review|volume=46|issue=8|pages=718–724|doi=10.1103/PhysRev.46.718|bibcode=1934PhRv...46..718L}}</ref>

==Physical properties==

===Boiling and melting points===
The boiling point of neopentane is only 9.5&nbsp;°C, significantly lower than those of isopentane (27.7&nbsp;°C) and normal pentane (36.0&nbsp;°C).  Therefore, neopentane is a gas at room temperature and atmospheric pressure, while the other two isomers are (barely) liquids.

The melting point of neopentane (−16.6&nbsp;°C), on the other hand, is 140 degrees higher than that of isopentane (−159.9&nbsp;°C) and 110 degrees higher than that of ''n''-pentane (−129.8&nbsp;°C). This anomaly has been attributed to the better solid-state packing assumed to be possible with the tetrahedral neopentane molecule; but this explanation has been challenged on account of it having a lower density<!--IN THE LIQUID STATE? IF SO, WHY IS IT RELEVENT? WHAT ABOUT THE SOLID STATE?--> than the other two isomers. Moreover, its [[enthalpy of fusion]] is lower than the enthalpies of fusion of both ''n''-pentane and isopentane, thus indicating that its high melting point is due to an entropy effect resulting from higher molecular symmetry. Indeed, the [[entropy of fusion]] of neopentane is about four times lower than that of ''n''-pentane and isopentane.<ref name="Wei">{{cite journal|first = James|last = Wei|year = 1999|title = Molecular Symmetry, Rotational Entropy, and Elevated Melting Points|journal = [[Ind. Eng. Chem. Res.]]|volume = 38|issue = 12|pages = 5019–5027|doi = 10.1021/ie990588m}}</ref>

===<sup>1</sup>H NMR spectrum===
Because of neopentane's [[tetrahedral symmetry#Achiral tetrahedral symmetry|full tetrahedral symmetry]], all protons are chemically equivalent, leading to a single [[nuclear magnetic resonance|NMR chemical shift]] ''δ''&nbsp;=&nbsp;0.902 when dissolved in [[carbon tetrachloride]].<ref>[[Spectral Database for Organic Compounds]], [http://sdbs.db.aist.go.jp/sdbs/cgi-bin/cre_frame_disp.cgi?spectrum_type=hnmr&amp;sdbsno=5425 Proton NMR spectrum of neopentane], accessed 4 Jun 2018.</ref> In this respect, neopentane is similar to its [[silane]] analog, [[tetramethylsilane]], whose single chemical shift is zero by convention.

The symmetry of the neopentane molecule can be broken if some hydrogen atoms are replaced by [[deuterium]] atoms.  In particular, if each methyl group has a different number of substituted atoms (0, 1, 2, and 3), one obtains a [[chirality (chemistry)|chiral]] molecule. The chirality in this case arises solely by the mass distribution of its nuclei, while the [[electron]] distribution is still essentially achiral.<ref>{{cite journal|title = Absolute configuration of chirally deuterated neopentane|journal = [[Nature (journal)|Nature]]|volume = 446|pages = 526–529|issue = 7135|year = 2007|doi = 10.1038/nature05653|last1 = Haesler|first1 = Jacques|last2 = Schindelholz|first2 = Ivan|last3 = Riguet|first3 = Emmanuel|last4 = Bochet|first4 = Christian G.|last5 = Hug|first5 = Werner|pmid = 17392783|bibcode = 2007Natur.446..526H|s2cid = 4423560|url = http://doc.rero.ch/record/7838/files/hug_acc.pdf}}</ref>

== Derivatives ==
The [[alcohol (chemistry)|alcohol]] [[pentaerythritol]] can be described as the result of replacing one hydrogen in each of the four methyl groups by a [[hydroxyl]] (–OH) group.

A linear polymer with alternating neopentane and [[orthocarbonate]] groups, which can be described as an [[ester]] ([[pentaerythritol]] orthocarbonate) with formula {{chem2|[(\sCH2)2C(CH2\s)2 (\sO)2C(O\s)2]_{''n''}|}}, was synthesized in 2002.<ref name=voda2002>{{cite journal | doi = 10.1021/ja017683i | title = One-Step Synthesis and Structure of an Oligo(spiro-orthocarbonate) | date = 2002 | last1 = Vodak | first1 = David T. | last2 = Braun | first2 = Matthew | last3 = Iordanidis | first3 = Lykourgos | last4 = Plévert | first4 = Jacques | last5 = Stevens | first5 = Michael | last6 = Beck | first6 = Larry | last7 = Spence | first7 = John C. H. | last8 = O'Keeffe | first8 = Michael | last9 = Yaghi | first9 = Omar M. | journal = Journal of the American Chemical Society | volume = 124 | issue = 18 | pages = 4942–4943 | pmid = 11982342 }}</ref>

==References==
{{Reflist}}

==External links==
*{{nist}}
*[http://www.acdlabs.com/iupac/nomenclature/ IUPAC Nomenclature of Organic Chemistry] (online version of the "''Blue Book''")

{{Alkanes}}

[[Category:Alkanes]]