Heptanes

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Heptane are among the alkanes counting hydrocarbons having the empirical formula C 7 H 16 . There are nine constitutional isomers :

  1. n -heptane
  2. 2-methylhexane
  3. 3-methylhexane
  4. 2,2-dimethylpentane
  5. 2,3-dimethylpentane
  6. 2,4-dimethylpentane
  7. 3,3-dimethylpentane
  8. 3-ethylpentane
  9. 2,2,3-trimethylbutane

3-methylhexane and 2,3-dimethylpentane are chiral compounds of which two enantiomers exist; The center of chirality is C3, which has hydrogen as a substituent and a methyl, ethyl and propyl or isopropyl radical. They are the simplest of the chiral alkanes.

Heptane isomers.svg

Comparison of physical properties of heptanes
Surname n -heptane 2-methylhexane 3-methylhexane 2,2-dimethylpentane 2,3-dimethylpentane 2,4-dimethylpentane 3,3-dimethylpentane 3-ethylpentane 2,2,3-trimethylbutane
other names Triptan
Structural formula (1) (2) (3) (4) (5) (6) (7) (8th) (9)
CAS number 142-82-5 591-76-4 589-34-4 590-35-2 565-59-3 108-08-7 562-49-2 617-78-7 464-06-2
78918-91-9 [( R ) -enantiomer ]
6131-24-4 [( S ) -enantiomer ]
PubChem 8900 11582 11507 11542 11260 7907 11229 12048 10044
Molecular formula C 7 H 16
Molar mass 100.21 g mol −1
Brief description colorless liquids
Melting point −91 ° C −118 ° C −119 ° C (racemate) −123 ° C −135 ° C approx. −120 ° C −135 ° C −118.3 ° C −25 ° C
boiling point 98 ° C 90 ° C 92 ° C 79 ° C 90 ° C 80 ° C 86 ° C 93 ° C 81 ° C
Vapor pressure (20 ° C) 47.4  hPa 111 hPa 71.8 hPa 191 hPa
(37.7 ° C)
Vapor pressure (30 ° C) 78.1 hPa 173 hPa 115 hPa
Vapor pressure (50 ° C) 189 hPa 275 hPa 255 hPa 383 hPa 264 hPa 365 hPa 235 hPa 385 hPa
density 0.68 g cm −3 0.68 g cm −3 0.69 g cm −3 0.67 g cm −3 0.70 g cm −3 0.67 g cm −3 0.69 g cm −3 0.70 g cm −3 0.69 g cm −3
solubility 2.2 mg l −1 (25 ° C) 2.5 mg l −1 (25 ° C) 2.6 mg l −1 (25 ° C) 4.4 mg l −1 (25 ° C) 5.3 mg l −1 (25 ° C) 4.4 mg l −1 (25 ° C) 5.9 mg l −1 (25 ° C) approx. 5.7 mg l −1 (25 ° C)
Flash point −7 ° C −10 ° C approx. −11 ° C approx. −21 ° C approx. −12 ° C <−20 ° C approx. −15 ° C −18 ° C approx. −19 ° C
Lower explosion limit (LEL) 0.84% ​​by volume 1.0% by volume 1% by volume approx. 0.9% by volume 1.1% by volume approx. 0.9% by volume 0.9% by volume
35 g m −3 42 g m −3 approx. 40 g m −3 45 g m −3 approx. 40 g m −3 40 g m −3
Upper explosion limit (UEL) 6.7% by volume 6.0% by volume 7% by volume 6.9% by volume 6.8% by volume approx. 6.9% by volume 6.9% by volume
280 g m −3 250 g m −3 285 g m −3 280 g m −3 approx. 285 g m −3 285 g m −3
Ignition temperature 220 ° C 280 ° C 280 ° C 320 ° C 330 ° C approx. 325 ° C approx. 320 ° C 450 ° C

Historical

Carl Schorlemmer was one of the first to investigate the isomers of heptane in more detail . In 1873 he described z. B. 3,3-dimethylpentane (called by him "dimethyl diethyl methane") and 3- ethyl pentane ("triethyl methane").

Individual evidence

  1. all data was taken from the GESTIS substance database , the individual links are in the name line.
  2. Entry on heptane in the GESTIS substance database of the IFA , accessed on July 26, 2019(JavaScript required) .
  3. Entry on 2-methylhexane in the GESTIS substance database of the IFA , accessed on July 26, 2019(JavaScript required) .
  4. Entry for CAS no. 589-34-4 in the GESTIS substance database of the IFA , accessed on July 26, 2019(JavaScript required) .
  5. Entry for CAS no. 590-35-2 in the GESTIS substance database of the IFA , accessed on July 28, 2019(JavaScript required) .
  6. Entry for CAS no. 565-59-3 in the GESTIS substance database of the IFA , accessed on July 28, 2019(JavaScript required) .
  7. Entry for CAS no. 108-08-7 in the GESTIS substance database of the IFA , accessed on July 29, 2019(JavaScript required) .
  8. Entry for CAS no. 562-49-2 in the GESTIS substance database of the IFA , accessed on July 29, 2019(JavaScript required) .
  9. Entry for CAS no. 617-78-7 in the GESTIS substance database of the IFA , accessed on July 29, 2019(JavaScript required) .
  10. Entry for CAS no. 464-06-2 in the GESTIS substance database of the IFA , accessed on July 29, 2019(JavaScript required) .
  11. Streiff, AJ; Murphy, ET; Sedlak, VA; Willingham, CB; Rossini, FD: Purification, Purity, and Freezing Points of 7 Heptanes, 16 Octanes, 6 Pentene, Cyclopentene, and 7 C9H12 Alkylbenzenes of the API-Standard and API-NBS Series in J. Res. Natl. Bur. Stand. (US) 37 (1946) 331.
  12. Carl Schorlemmer: About the heptanes in stone oil . In: F. Wöhler, J. Liebig, H. Kopp, E. Erlenmeyer, J. Volhard (Eds.): Justus Liebigs Annalen der Chemie . tape 166 , no. 2 . CF Winter'sche Verlagshandlung / Wiley-VCH, Leipzig and Heidelberg 1873, p. 172–178 , doi : 10.1002 / jlac.18731660207 ( online at the Bayerische Staatsbibliothek BSB / Munich Digitization Center (MDZ) [accessed on January 14, 2016]).