2-methylhexane

Structural formula
General
Surname	2-methylhexane
other names	Isoheptane
Molecular formula	C 7 H 16
Brief description	highly flammable, volatile liquid
External identifiers / databases
EC number	209-730-6
ECHA InfoCard	100,008,847
PubChem	11582
Wikidata	Q183300
properties
Molar mass	100.21 g mol −1
Physical state	liquid
density	0.68 g cm −3
Melting point	−118 ° C
boiling point	90 ° C
Vapor pressure	53.3 hPa (15 ° C); 275 hPa (50 ° C);
solubility	practically insoluble in water (2.5 mg l −1 at 25 ° C)
Refractive index	1.3848 (20 ° C)
safety instructions
H and P phrases	H: 225-304-315-336-410
	P: 210-261-273-301 + 310-331-501
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

2-methylhexane is a chemical compound from the group of aliphatic saturated hydrocarbons . It is one of the nine constitutional isomers of heptane .

Extraction and presentation

2-methylhexane occurs in petroleum . The compound can also be obtained by the isomerization of n-heptane . In 1927 a laboratory synthesis was described in which the Grignard compound from n-butyl magnesium bromide is reacted with acetone . The resulting 2-methyl-2-hexanol is used for 2-hexene, 2-methyl- dehydrated , and then by means of Nickelkatalysor to the 2-methylhexane hydrogenated .

properties

Physical Properties

2-methylhexane is a highly flammable, volatile, colorless liquid. The vapor pressure function results according to Antoine according to log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.00653, B = 1240.869 and C = −53.047 in the temperature range from 292 to 364 K. The temperature dependence of the enthalpy of vaporization can be calculated according to the equation Δ _V H ⁰ = Aexp (−βT _r ) (1 − T _r ) ^β (Δ _V H ⁰ in kJ / mol, T _r = (T / T _c ) reduced temperature) with A = 52 kJ / mol, β = 0.2879 and T _c = 530.3 K in the temperature range between 298 K and 353 K.

The most important thermodynamic properties are listed in the following table:

property	Type	Value [unit]
Standard enthalpy of formation	Δ _f H ⁰_gas Δ _f H ⁰_liquid	−196.2 kJ mol ⁻¹ −231 kJ mol ⁻¹
Enthalpy of combustion	Δ _c H ⁰_liquid	−4810 kJ mol ⁻¹
Heat capacity	c _p	222.92 J mol ⁻¹ K ⁻¹ (25 ° C) as a liquid
Enthalpy of fusion	Δ _f H ⁰	9.184 kJ mol ⁻¹ at the melting point
Entropy of fusion	Δ _f S ⁰	59.29 kJ mol ⁻¹ at the melting point
Enthalpy of evaporation	Δ _V H ⁰	30.62 kJ mol ⁻¹ at the normal pressure boiling point 34.98 kJ mol ⁻¹ at 25 ° C
Critical temperature	T _C	257.3 ° C
Critical pressure	P _C	27.4 bar
Critical volume	V _C	0.421 l mol ⁻¹
Critical density	ρ _C	2.38 mol·l ⁻¹

Vapor pressure function of 2-methylhexane
Temperature dependence of the heat of vaporization of 2-methylhexane

Safety-related parameters

2-methylhexane forms highly flammable vapor-air mixtures. The compound has a flash point of −10 ° C. The explosion range is between 1.0% by volume (42 g / m ³ ) as the lower explosion limit (LEL) and 6.0% by volume (250 g / m ³ ) as the upper explosion limit (UEL). The ignition temperature is 280 ° C. The substance therefore falls into temperature class T3.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on 2-methylhexane in the GESTIS substance database of the IFA , accessed on August 9, 2016(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-354.
↑ Haensel, V .; Donaldson, GR: Platforming of Pure Hydrocarbons in Ind. Eng. Chem. 43 (1951) 2102-2104, doi : 10.1021 / ie50501a036 .
↑ Blomsma, E .; Martens, YES; Jacobs, PA: Reaction Mechanisms of Isomerization and Cracking of Heptane on Pd / H-Beta Zeolite in J. Catal. 155 (1995) 141-147, doi : 10.1006 / jcat.1995.1195 .
↑ Edgar, G .; Calingaert, G .; Marker, RE: The preparation and properties of the isomeric heptanes. Part I. Preparation in J. Am. Chem. Soc. 51 (1929) 1483-1491, doi : 10.1021 / ja01380a027 .
↑ Forziati, AF; Norris, WR; Rossini, FD: Vapor Pressures and Boiling Points of Sixty API-NBS Hydrocarbons in J. Res. Natl. Bur. Stand. (US) 43 (1949) 555-563.
↑ ^a ^b ^c Majer, V .; Svoboda, V .: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation , Blackwell Scientific Publications, Oxford, 1985, p. 300.
↑ ^a ^b ^c Davies, GF; Gilbert, EC: Heats of combustion and formation of the nine isomeric heptanes in the liquid state in J. Am. Chem. Soc. 63 (1941) 2730-2732, doi : 10.1021 / ja01855a064 .
↑ ^a ^b ^c Huffman, HM; Gross, ME; Scott, DW; McCullough, IP: Low temperature thermodynamic properties of six isomeric heptanes in J. Phys. Chem. 65 (1961) 495-503, doi : 10.1021 / j100821a026 .
↑ ^a ^b ^c ^d Daubert, TE: Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes in J. Chem. Eng. Data 41 (1996) 365-372, doi : 10.1021 / je9501548 .
^ ^A ^b E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on 2-methylhexane in the GESTIS substance database of the IFA , accessed on August 9, 2016(JavaScript required) .

[CRC90_3_354-2] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-354.

[3] Haensel, V .; Donaldson, GR: Platforming of Pure Hydrocarbons in Ind. Eng. Chem. 43 (1951) 2102-2104, doi : 10.1021 / ie50501a036 .

[4] Blomsma, E .; Martens, YES; Jacobs, PA: Reaction Mechanisms of Isomerization and Cracking of Heptane on Pd / H-Beta Zeolite in J. Catal. 155 (1995) 141-147, doi : 10.1006 / jcat.1995.1195 .

[5] Edgar, G .; Calingaert, G .; Marker, RE: The preparation and properties of the isomeric heptanes. Part I. Preparation in J. Am. Chem. Soc. 51 (1929) 1483-1491, doi : 10.1021 / ja01380a027 .

[Forziati-6] Forziati, AF; Norris, WR; Rossini, FD: Vapor Pressures and Boiling Points of Sixty API-NBS Hydrocarbons in J. Res. Natl. Bur. Stand. (US) 43 (1949) 555-563.

[Majer_Svoboda-7] Majer, V .; Svoboda, V .: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation , Blackwell Scientific Publications, Oxford, 1985, p. 300.

[Davies-8] Davies, GF; Gilbert, EC: Heats of combustion and formation of the nine isomeric heptanes in the liquid state in J. Am. Chem. Soc. 63 (1941) 2730-2732, doi : 10.1021 / ja01855a064 .

[Huffmann-9] Huffman, HM; Gross, ME; Scott, DW; McCullough, IP: Low temperature thermodynamic properties of six isomeric heptanes in J. Phys. Chem. 65 (1961) 495-503, doi : 10.1021 / j100821a026 .

[Daubert-10] Daubert, TE: Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes in J. Chem. Eng. Data 41 (1996) 365-372, doi : 10.1021 / je9501548 .

[Brandes-11] A ^b E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.