Isobutane

Isobutane

Names
Preferred IUPAC name Methylpropane
Other names Isobutane (no longer recommended)
Identifiers
CAS Number	75-28-5 Y
3D model (Jmol)	Interactive image
Beilstein Reference	1730720
ChEBI	CHEBI:30363 Y
ChemSpider	6120 Y
ECHA InfoCard	100.000.780
EC Number	200-857-2
E number	E943b (glazing agents, ...)
Gmelin Reference	1301
KEGG	D04623 N
PubChem	6360
RTECS number	TZ4300000
UNII	BXR49TP611 Y
UN number	1969
InChI InChI=1S/C4H10/c1-4(2)3/h4H,1-3H3 Y Key: NNPPMTNAJDCUHE-UHFFFAOYSA-N Y
SMILES CC(C)C
Properties
Chemical formula	C4H10
Molar mass	58.12 g·mol−1
Appearance	Colorless gas
Odor	Odorless
Density	2.51 kg/m3 (at 15 °C, 100 kPa)
Melting point	−159.42 °C (−254.96 °F; 113.73 K)
Boiling point	−11.7 °C (10.9 °F; 261.4 K)
Vapor pressure	204.8 kPa (at 21 °C (70 °F))
Henry's law constant (kH)	8.6 nmol Pa−1 kg−1
Magnetic susceptibility (χ)	-51.7·10−6 cm3/mol
Thermochemistry
Specific heat capacity (C)	96.65 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)	−134.8–−133.6 kJ mol−1
Std enthalpy of combustion (ΔcHo298)	−2.86959–−2.86841 MJ mol−1
Hazards
Safety data sheet	See: data page praxair.com
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H220
GHS precautionary statements	P210
EU classification (DSD)	F+
R-phrases	R12
S-phrases	(S2), S16
NFPA 704	4 1 0
Flash point	−83 °C (−117 °F; 190 K)
Autoignition temperature	460 °C (860 °F; 733 K)
Explosive limits	1.4–8.3%
US health exposure limits (NIOSH):
PEL (Permissible)	none
REL (Recommended)	TWA 800 ppm (1900 mg/m3)
IDLH (Immediate danger)	N.D.
Related compounds
Related alkane	Isopentane
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Isobutane (i-butane), also known as methylpropane, is a chemical compound with molecular formula C
4H
10 and is an isomer of butane. It is the simplest alkane with a tertiary carbon. Concerns with depletion of the ozone layer by freon gases have led to increased use of isobutane as a gas for refrigeration systems, especially in domestic refrigerators and freezers, and as a propellant in aerosol sprays.

When used as a refrigerant or a propellant, isobutane is also known as R-600a. Some portable camp stoves use a mixture of isobutane with propane, usually 80:20. Isobutane is used as a feedstock in the petrochemical industry, for example in the synthesis of isooctane.

The traditional name isobutane was still retained in the 1993 IUPAC recommendations, but is no longer recommended according to the 2013 recommendations. Since the longest continuous chain in isobutane contains only three carbon atoms, the preferred IUPAC name is 2-methylpropane but the locant (2-) is typically omitted in general nomenclature as redundant; C2 is the only position on a propane chain where a methyl substituent can be located without altering the main chain and forming the constitutional isomer n-butane.