2,2,3-trimethylbutane

Structural formula
General
Surname	2,2,3-trimethylbutane
other names	Triptan
Molecular formula	C 7 H 16
Brief description	colorless, highly flammable liquid
External identifiers / databases
CAS number 464-06-2 EC number 207-346-3 ECHA InfoCard 100.006.680 PubChem 10044 Wikidata Q209116
properties
Molar mass	100.21 g mol −1
Physical state	liquid
density	0.69 g cm −3
Melting point	−25.45 ° C
boiling point	81 ° C
Vapor pressure	385 mbar (50 ° C)
solubility	practically insoluble in water (5.7 mg l −1 at 25 ° C)
Refractive index	1.3864 (20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 225-304-315-336-410 P: 210-240-261-273-301 + 310-331-302 + 352
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

2,2,3-Trimethylbutane is a chemical compound from the group of aliphatic saturated hydrocarbons . It is one of the nine constitutional isomers of heptane .

Extraction and presentation

2,2,3-Trimethylbutane occurs in petroleum . The compound can be produced from cracking gases or by hydrodesalkylation of isooctane and, in small proportions, by isomerization of n-heptane . As early as 1927 a laboratory synthesis was described in which the Grignard compound from tert-butyl chloride is reacted with acetone . The resulting 2,2,3-trimethylbutane-3-ol is the 2,3,3-Trimethylbut-1-en dehydrated and then by means of nickel catalyst for 2,2,3-trimethylbutane hydrogenated .

properties

Physical Properties

2,2,3-Trimethylbutane is a highly flammable and 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 = 3.9222, B = 1203.362 and C = −46.776 in the temperature range from 286 to 355 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 / Describe T _c ) reduced temperature) with A = 46.76 kJ / mol, β = 0.2726 and T _c = 531.1 K in the temperature range between 298 K and 353 K. Two polymorphic crystal forms can occur in the solid phase . Below −151.75 ° C there is crystal form II, above this temperature there is crystal form I. The enthalpy of transformation of the solid phase transition is 2.242 kJ · mol ⁻¹ . The crystal form I melts at −25.45 ° C.

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	−205.9 kJ mol −1 −238 kJ mol −1
Enthalpy of combustion	Δ c H 0 liquid	−4803 kJ mol −1
Heat capacity	c p	213.51 J mol −1 K −1 (25 ° C) as a liquid
Enthalpy of fusion	Δ f H 0	2.2 kJ mol −1 at the melting point
Entropy of fusion	Δ f S 0	8.88 kJ mol −1 at the melting point
Enthalpy of evaporation	Δ V H 0	28.9 kJ mol −1 at the normal pressure boiling point of 32.19 kJ mol −1 at 25 ° C
Critical temperature	T C	257.9 ° C
Critical pressure	P C	29.5 bar
Critical volume	V C	0.398 l mol −1
Critical density	ρ C	2.51 mol·l −1

Safety-related parameters

2,2,3-Trimethylbutane forms highly flammable vapor-air mixtures. The compound has a flash point of −19 ° C. The ignition temperature is 450 ° C. The substance therefore falls into temperature class T2.

use

2,2,3-Trimethylbutane is used as a high-quality, very knock- resistant aircraft fuel with an octane number of 112. The substance also serves as a reference substance in gas chromatography .

Individual evidence

1. ↑ ^{a b c d e f g h i j} Entry on 2,2,3-trimethylbutane in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ ^{a b c d} Domalski, ES; Hearing, ED: Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III . In: J. Phys. Chem. Ref. Data 25 (1996) 1-525. doi : 10.1063 / 1.555985 .
3. ↑ 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. 3-506.
4. ↑ Lindeman, LP; Annis, JL: Use of a conventional mass spectrometer as a detector for gas chromatography in Anal. Chem. 32 (1960) 1742-1747, doi : 10.1021 / ac50153a011 .
5. ↑ ^{a b c d} Entry on 2,2,3-trimethylbutane. In: Römpp Online . Georg Thieme Verlag, accessed on June 14, 2014.
6. ↑ Haensel, V .; Donaldson, GR: Platforming of Pure Hydrocarbons in Ind. Eng. Chem. 43 (1951) 2102-2104, doi : 10.1021 / ie50501a036 .
7. ↑ 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 .
8. ↑ 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 .
9. ↑ 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) 555-567.
10. ↑ ^{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.
11. ↑ ^{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 .
12. ↑ ^{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 .
13. ↑ ^{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 .