Heptane

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Heptane
Heptane-2D-Skeletal.svg
HeptaneFull.png
Heptane 3D ball.png
Names
Preferred IUPAC name
Heptane [1]
Other names
Septane [2]
Identifiers
3D model (JSmol)
1730763
ChEBI
ChEMBL
ChemSpider
EC Number
  • 205-563-8
49760
MeSH n-heptane
PubChem CID
RTECS number
  • MI7700000
UNII
UN number 1206
  • InChI=1S/C7H16/c1-3-5-7-6-4-2/h3-7H2,1-2H3 Yes check.svgY
    Key: IMNFDUFMRHMDMM-UHFFFAOYSA-N Yes check.svgY
  • CCCCCCC
Properties
C7H16
Molar mass 100.205 g·mol−1
AppearanceColourless liquid
Odor Petrolic
Density 0.6795 g cm−3 [3]
Melting point −90.549 [3]  °C (−130.988 °F; 182.601 K)
Boiling point 98.38 [3]  °C (209.08 °F; 371.53 K)
0.0003% (20 °C) [4]
log P 4.274
Vapor pressure 5.33 kPa (at 20.0 °C)
12 nmol Pa−1 kg−1
−85.24·10−6 cm3/mol
1.3855 [3]
Viscosity 0.389 mPa·s [5]
0.0 D
Thermochemistry
224.64 J K−1 mol−1
Std molar
entropy (S⦵298)
328.57 J K−1 mol−1
−225.2 – −223.6 kJ mol−1
−4.825 – −4.809 MJ mol−1
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H225, H304, H315, H336, H410
P210, P261, P273, P301+P310, P331
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
3
0
Flash point −4.0 °C (24.8 °F; 269.1 K)
223.0 °C (433.4 °F; 496.1 K)
Explosive limits 1.05–6.7%
Lethal dose or concentration (LD, LC):
17,986 ppm (mouse, 2 hr) [6]
16,000 ppm (human)
15,000 ppm (mouse, 30 min) [6]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 500 ppm (2000 mg/m3) [4]
REL (Recommended)
TWA 85 ppm (350 mg/m3) C 440 ppm (1800 mg/m3) [15-minute] [4]
IDLH (Immediate danger)
750 ppm [4]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Heptane or n-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 point is 100% iso-octane). Octane number equates to the anti-knock qualities of a comparison mixture of heptane and iso-octane which is expressed as the percentage of iso-octane in heptane, and is listed on pumps for gasoline (petrol) dispensed globally.

Uses

Heptane and its many isomers are widely used in laboratories as a non-polar solvent. [7] As a liquid, it is ideal for transport and storage. In the grease spot test, heptane is used to dissolve an oil spot to show the previous presence of organic compounds on a stained paper. This is done by shaking the stained paper in a heptane solution for about half a minute.[ citation needed ]

Aqueous bromine may be distinguished from aqueous iodine by its appearance after extraction into heptane. In water, both bromine and iodine appear brown. However, iodine turns purple when dissolved in heptane, whereas the bromine solution remains brown.

Heptane is commercially available as mixed isomers for use in paints and coatings, as the rubber cement solvent "Bestine", the outdoor stove fuel "Powerfuel" by Primus, as pure n-heptane for research and development and pharmaceutical manufacturing and as a minor component of gasoline (petrol). On average, gasoline is about 1% heptane. [8] [9]

Heptane is also used as an adhesive remover by stamp collectors. Since 1974, the United States Postal Service has issued self-adhesive stamps that some collectors find difficult to separate from envelopes via the traditional method of soaking in water. Heptane-based products like Bestine, as well as limonene-based products, have become popular solvents for removing stamps more easily. [10]

Octane rating scale

n-Heptane is defined as the zero point of the octane rating scale. It is a lighter component in gasoline, burns more explosively, causing engine pre-ignition (knocking) in its pure form, as opposed to octane isomers, which burn more slowly and give less knocking. It was originally chosen as the zero point of the scale because of the availability of very high purity n-heptane, unmixed with other isomers of heptane or other alkanes, distilled from the resin of Jeffrey pine and from the fruit of Pittosporum resiniferum . Other sources of heptane and octane, produced from crude oil, contain a mixture of different isomers with greatly differing ratings, and do not give as precise a zero point.

Isomers and enantiomers

Heptane has nine isomers, or eleven if enantiomers are counted:

Preparation

The linear n-heptane can be obtained from Jeffrey pine oil. [12] The six branched isomers without a quaternary carbon can be prepared by creating a suitable secondary or tertiary alcohol by the Grignard reaction, converting it to an alkene by dehydration, and hydrogenating the latter. [12] The 2,2-dimethylpentane isomer can be prepared by reacting tert-butyl chloride with n-propyl magnesium bromide. [12] The 3,3-dimethylpentane isomer can be prepared from tert-amyl chloride and ethyl magnesium bromide. [12]

Health risks

Acute exposure to heptane vapors can cause dizziness, stupor, incoordination, loss of appetite, nausea, dermatitis, chemical pneumonitis, unconsciousness, or possible peripheral neuropathy. [13]

In a CDC study, it was found that prolonged exposure to heptane may also cause a state of intoxication and uncontrolled hilarity in some participants and a stupor lasting for 30 minutes after exposure for others. [14] Prolonged exposure can also lead to skin dryness or cracking, since the substance defats skin. [15]

According to information from the New Jersey Department of Health and Senior Services, n-heptane can penetrate the skin, and further health effects may occur immediately or shortly after exposure to it. Exposure to n-heptane may lead to: short-term health effects, like irritation of the eyes, nose, or throat, headache, dizziness, or loss of consciousness; and chronic health effects, like reduced memory and concentration, sleep disturbance, or reduced coordination due to its effects on the nervous system. [16]

Upon chronic exposure, it can pose a reproductive hazard or cancer risks. [17]

Related Research Articles

<span class="mw-page-title-main">Alkane</span> Type of saturated hydrocarbon compound

In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.

<span class="mw-page-title-main">Alkene</span> Hydrocarbon compound containing one or more C=C bonds

In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.

<span class="mw-page-title-main">Toluene</span> Chemical compound

Toluene, also known as toluol, is a substituted aromatic hydrocarbon with the chemical formula C6H5CH3, often abbreviated as PhCH3, where Ph stands for the phenyl group. It is a colorless, water-insoluble liquid with the odor associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) attached to a phenyl group by a single bond. As such, its systematic IUPAC name is methylbenzene. Toluene is predominantly used as an industrial feedstock and a solvent.

<span class="mw-page-title-main">Hexane</span> Chemical compound

Hexane or n-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14.

<span class="mw-page-title-main">Octane</span> Hydrocarbon compound with the formula C8H18

Octane is a hydrocarbon and an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.

Decane is an alkane hydrocarbon with the chemical formula C10H22. Although 75 structural isomers are possible for decane, the term usually refers to the normal-decane ("n-decane"), with the formula CH3(CH2)8CH3. All isomers, however, exhibit similar properties and little attention is paid to the composition. These isomers are flammable liquids. Decane is present in small quantities (less than 1%) in gasoline (petrol) and kerosene. Like other alkanes, it is a nonpolar solvent, and does not dissolve in water, and is readily combustible. Although it is a component of fuels, it is of little importance as a chemical feedstock, unlike a handful of other alkanes.

<span class="mw-page-title-main">Pentane</span> Alkane with 5 carbon atoms

Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12.

<span class="mw-page-title-main">Nonane</span> Chemical compound

Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, and jet fuel. Nonane is also used as a solvent, distillation chaser, fuel additive, and a component in biodegradable detergents. It is also a minor component of the diesel fuel.

<span class="mw-page-title-main">Hydrogen bromide</span> Chemical compound

Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.

In organic chemistry, free-radical halogenation is a type of halogenation. This chemical reaction is typical of alkanes and alkyl-substituted aromatics under application of UV light. The reaction is used for the industrial synthesis of chloroform (CHCl3), dichloromethane (CH2Cl2), and hexachlorobutadiene. It proceeds by a free-radical chain mechanism.

<span class="mw-page-title-main">Amyl acetate</span> Chemical compound

Amyl acetate (pentyl acetate) is an organic compound and an ester with the chemical formula CH3COO[CH2]4CH3 and the molecular weight 130.19 g/mol. It is colorless and has a scent similar to bananas and apples. The compound is the condensation product of acetic acid and 1-pentanol. However, esters formed from other pentanol isomers (amyl alcohols), or mixtures of pentanols, are often referred to as amyl acetate. The symptoms of exposure to amyl acetate in humans are dermatitis, central nervous system depression, narcosis and irritation to the eyes and nose.

<i>tert</i>-Butyl alcohol Chemical compound

tert-Butyl alcohol is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). Its isomers are 1-butanol, isobutanol, and butan-2-ol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

<span class="mw-page-title-main">2,2-Dimethylbutane</span> Chemical compound

2,2-Dimethylbutane, trivially known as neohexane at William Odling's 1876 suggestion, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.

<span class="mw-page-title-main">1,2-Dichlorobenzene</span> Chemical compound

1,2-Dichlorobenzene, or orthodichlorobenzene (ODCB), is an aryl chloride and isomer of dichlorobenzene with the formula C6H4Cl2. This colourless liquid is poorly soluble in water but miscible with most organic solvents. It is a derivative of benzene, consisting of two adjacent chlorine atoms.

<span class="mw-page-title-main">2-Methylhexane</span> Chemical compound

2-Methylhexane (C7H16, also known as isoheptane, ethylisobutylmethane) is an isomer of heptane. It is structurally a hexane molecule with a methyl group attached to its second carbon atom. It exists in most commercially available heptane merchandises as an impurity but is usually not considered as impurity in terms of reactions since it has very similar physical and chemical properties when compared to n-heptane (straight-chained heptane).

<i>n</i>-Butylamine Chemical compound

n-Butylamine is an organic compound (specifically, an amine) with the formula CH3(CH2)3NH2. This colourless liquid is one of the four isomeric amines of butane, the others being sec-butylamine, tert-butylamine, and isobutylamine. It is a liquid having the fishy, ammonia-like odor common to amines. The liquid acquires a yellow color upon storage in air. It is soluble in all organic solvents. Its vapours are heavier than air and it produces toxic oxides of nitrogen during combustion.

<span class="mw-page-title-main">Triptane</span> Chemical compound

Triptane, or 2,2,3-trimethylbutane, is an organic chemical compound with the molecular formula C7H16 or (H3C-)3C-C(-CH3)2H. It is therefore an alkane, specifically the most compact and heavily branched of the heptane isomers, the only one with a butane (C4) backbone.

<span class="mw-page-title-main">2,2-Dimethylpentane</span> Chemical compound

2,2-Dimethylpentane is one of the isomers of heptane. It is also called neoheptane as it contains the (CH3)3C grouping. It has the most extreme properties of the isomers of heptane.

Bis(2-ethylhexyl) maleate is the chemical compound with the structural formula (H3C 3−CH −CH2−O−C −CH=)2, where the two carboxylate groups are mutually cis. It can be described as the double ester of maleic acid with the alcohol 2-ethylhexanol. It is commonly called dioctyl maleate (DOM), reflecting the older usage of "octane" to refer to any 8-carbon alkane, straight-chained or branched.

<span class="mw-page-title-main">2,3-Dimethylpentane</span> Chemical compound

2,3-Dimethylpentane is an organic compound of carbon and hydrogen with formula C
7H
16, more precisely CH
3–CH(CH
3)–CH(CH
3)–CH
2–CH
3: a molecule of pentane with methyl groups –CH
3 replacing hydrogen atoms on carbon atoms 2 and 3. It is an alkane, a fully saturated hydrocarbon; specifically, one of the isomers of heptane.

References

  1. ↑ "n-heptane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 2 January 2012.
  2. ↑ Hofmann, August Wilhelm Von (1 January 1867). "I. On the action of trichloride of phosphorus on the salts of the aromatic monamines". Proceedings of the Royal Society of London. 15: 54–62. doi:10.1098/rspl.1866.0018. S2CID   98496840.
  3. 1 2 3 4 Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 3.290. ISBN   1-4398-5511-0.
  4. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0312". National Institute for Occupational Safety and Health (NIOSH).
  5. ↑ Dymond, J. H.; Oye, H. A. (1994). "Viscosity of Selected Liquid n-Alkanes". Journal of Physical and Chemical Reference Data. 23 (1): 41–53. Bibcode:1994JPCRD..23...41D. doi:10.1063/1.555943. ISSN   0047-2689.
  6. 1 2 "n-Heptane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  7. ↑ Fang, Shen; Zhang, Siyi; Li, Zeyu; Fu, Qingfei; Zhou, Chong-Wen; Hana, Wang; Yang, Lijun (13 October 2024), A data-driven sparse learning approach to reduce chemical reaction mechanisms, doi:10.48550/arXiv.2410.09901 , retrieved 10 December 2024
  8. ↑ Conner, Teri L.; Lonneman, William A.; Seila, Robert L. (1 May 1995). "Transportation-Related Volatile Hydrocarbon Source Profiles Measured in Atlanta". Journal of the Air & Waste Management Association. 45 (5): 383–394. Bibcode:1995JAWMA..45..383C. doi: 10.1080/10473289.1995.10467370 .
  9. ↑ Schauer, James J.; Kleeman, Michael J.; Cass, Glen R.; Simoneit, Bernd R. T. (1 March 2002). "Measurement of Emissions from Air Pollution Sources. 5. C 1 −C 32 Organic Compounds from Gasoline-Powered Motor Vehicles". Environmental Science & Technology. 36 (6): 1169–1180. Bibcode:2002EnST...36.1169S. doi:10.1021/es0108077. PMID   11944666.
  10. ↑ Butler, Peter. "It's Like Magic: Removing Self-Adhesive Stamps from Paper" (PDF). American Philatelic Society. Retrieved 15 June 2020.
  11. ↑ Isomers Archived 27 September 2011 at the Wayback Machine . Members.optushome.com.au. Retrieved on 2012-03-04.
  12. 1 2 3 4 Edgar, Graham; Calingaert, George; Marker, R. E. (1929). "The preparation and properties of the isomeric heptanes. Part I. Preparation". Journal of the American Chemical Society. 51 (5): 1483–1491. doi:10.1021/ja01380a027.
  13. ↑ Patty, FA; Yant, WP (1929). "Odor intensity and symptoms produced by commercial propane, butane, pentane, hexane, and heptane vapor". Report of Investigations. 2979 (December). US Department of Commerce, U.S. Bureau of Mines: 1–10.
  14. ↑ "CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): n-Heptane - NIOSH Publications and Products". www.cdc.gov. 2 November 2018. Retrieved 6 December 2021.
  15. ↑ "ICSC 0657 - n-HEPTANE". chemicalsafety.ilo.org. Retrieved 11 September 2024.
  16. ↑ "n- HEPTANE" (PDF).
  17. ↑ "Hazardous Substance Fact Sheet" (PDF). 2004. p. 2. Retrieved 11 September 2024.
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