Heptane
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| Names | |
|---|---|
| Preferred IUPAC name
Heptane[2] | |
| Other names
Septane[1]
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| Identifiers | |
3D model (JSmol)
|
|
| 1730763 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| EC Number |
|
| 49760 | |
| MeSH | n-heptane |
PubChemCID
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| RTECS number |
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| UNII | |
| UN number | 1206 |
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| Properties | |
| C7H16 | |
| Molar mass | 100.205g·mol−1 |
| Appearance | Colourless 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] | |
| logP | 4.274 |
| Vapor pressure | 5.33 kPa (at 20.0 °C) |
| 12 nmol Pa−1kg−1 | |
| −85.24·10−6cm3/mol | |
Refractive index(nD)
|
1.3855[3] |
| Viscosity | 0.389 mPa·s[5] |
| 0.0 D | |
| Thermochemistry | |
| 224.64 J K−1mol−1 | |
Std molar
entropy(S⦵298) |
328.57 J K−1mol−1 |
Std enthalpy of
formation(ΔfH⦵298) |
−225.2 – −223.6 kJ mol−1 |
Std enthalpy of
combustion(ΔcH⦵298) |
−4.825 – −4.809 MJ mol−1 |
| Hazards | |
| GHSlabelling: | |
   
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| Danger | |
| H225,H304,H315,H336,H410 | |
| P210,P261,P273,P301+P310,P331 | |
| NFPA 704(fire diamond) | |
| 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 doseor concentration (LD, LC): | |
LC50(median concentration)
|
17,986 ppm (mouse, 2 hr)[6] |
LCLo(lowest published)
|
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
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Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).
| |
Heptaneorn-heptaneis the straight-chainalkanewith thechemical formulaH3C(CH2)5CH3or C7H16.When used as a test fuel component inanti-knocktest engines, a 100% heptane fuel is the zero point of theoctane ratingscale (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 forgasoline(petrol) dispensed globally.
Uses
[edit]Heptane and its many isomers are widely used inlaboratoriesas a non-polarsolvent.As aliquid,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]
Aqueousbrominemay be distinguished from aqueousiodineby its appearance afterextractioninto heptane. In water, both bromine and iodine appearbrown.However, iodine turnspurplewhen dissolved in heptane, whereas the bromine solution remains brown.
Heptane is commercially available as mixed isomers for use in paints and coatings, as therubber cementsolvent "Bestine", the outdoor stove fuel "Powerfuel" by Primus, as puren-heptane for research and development and pharmaceutical manufacturing and as a minor component ofgasoline(petrol). On average, gasoline is about 1% heptane.[7][8]
Heptane is also used as anadhesive removerbystamp collectors.Since 1974, theUnited States Postal Servicehas issuedself-adhesive stampsthat some collectors find difficult to separate from envelopes via the traditional method of soaking in water. Heptane-based products like Bestine, as well aslimonene-based products, have become popular solvents for removing stamps more easily.[9]
Octane rating scale
[edit]n-Heptane is defined as the zero point of theoctane ratingscale. It is a lighter component ingasoline,burns moreexplosively,causingenginepre-ignition (knocking) in its pure form, as opposed tooctaneisomers, 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 purityn-heptane, unmixed with other isomers of heptane or other alkanes, distilled from theresinofJeffrey pineand from the fruit ofPittosporum resiniferum.Other sources of heptane and octane, produced fromcrude oil,contain a mixture of different isomers with greatly differing ratings, and do not give as precise a zero point.
Isomers and enantiomers
[edit]Heptane has nineisomers,or eleven ifenantiomersare counted:
- Heptane (n-heptane), H3C–CH2–CH2–CH2–CH2–CH2–CH3,
- 2-Methylhexane(isoheptane), H3C–CH(CH3)–CH2–CH2–CH2–CH3,
- 3-Methylhexane,H3C–CH2–C*H(CH3)–CH2–CH2–CH3(chiral),
- 2,2-Dimethylpentane(neoheptane), H3C–C(CH3)2–CH2–CH2–CH3,
- 2,3-Dimethylpentane,H3C–CH(CH3)–C*H(CH3)–CH2–CH3(chiral),
- 2,4-Dimethylpentane,H3C–CH(CH3)–CH2–CH(CH3)–CH3,
- 3,3-Dimethylpentane,H3C–CH2–C(CH3)2–CH2–CH3,
- 3-Ethylpentane,H3C–CH2–CH(CH2CH3)–CH2–CH3,
- 2,2,3-Trimethylbutane,H3C–C(CH3)2–CH(CH3)–CH3,this isomer is also known as pentamethylethane and triptane.[10]
Preparation
[edit]The linearn-heptane can be obtained fromJeffrey pineoil.[11]The six branched isomers without a quaternary carbon can be prepared by creating a suitable secondary or tertiaryalcoholby theGrignard reaction,converting it to analkenebydehydration,andhydrogenatingthe latter.[11]The 2,2-dimethylpentane isomer can be prepared by reactingtert-butyl chloride withn-propyl magnesium bromide.[11]The 3,3-dimethylpentane isomer can be prepared fromtert-amyl chloride and ethyl magnesium bromide.[11]
Health risks
[edit]![[icon]](/translate/en.wikipedia.org?u=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFile%3AWiki_letter_w_cropped.svg&t=hv){kind=small} | This sectionneeds expansion.You can help byadding to it.(June 2015) |
Acute exposure to heptane vapors can causedizziness,stupor, incoordination, loss of appetite, nausea, dermatitis, chemical pneumonitis, unconsciousness, or possible peripheral neuropathy.[12]
In aCDCstudy, it was found that prolonged exposure to heptane may also cause a state ofintoxicationand uncontrolled hilarity in some participants and astuporlasting for 30 minutes after exposure for others.[13]
According to information from the New Jersey Department of Health and Senior Services,n-heptane can penetrate through the skin and further health effects may occur immediately or shortly after exposure to it. Exposure ton-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.[14]
References
[edit]- ^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.S2CID98496840.
- ^"n-heptane – Compound Summary".PubChem Compound.USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records.Retrieved2 January2012.
- ^abcdHaynes, William M., ed. (2011).CRC Handbook of Chemistry and Physics(92nd ed.). Boca Raton, FL:CRC Press.p. 3.290.ISBN1-4398-5511-0.
- ^abcdNIOSH Pocket Guide to Chemical Hazards."#0312".National Institute for Occupational Safety and Health(NIOSH).
- ^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.ISSN0047-2689.
- ^ab"n-Heptane".Immediately Dangerous to Life or Health Concentrations (IDLH).National Institute for Occupational Safety and Health(NIOSH).
- ^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.
- ^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.PMID11944666.
- ^Butler, Peter."It's Like Magic: Removing Self-Adhesive Stamps from Paper"(PDF).American Philatelic Society.Retrieved15 June2020.
- ^IsomersArchived27 September 2011 at theWayback Machine.Members.optushome.com.au. Retrieved on 2012-03-04.
- ^abcdGraham Edgar, George Calingaert, and R. E. Marker (1929): "The preparation and properties of the isomeric heptanes. Part I. Preparation".Journal of the American Chemical Society,volume 51, issue 5, pages 1483–1491.doi:10.1021/ja01380a027
- ^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.
- ^"CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): n-Heptane - NIOSH Publications and Products".www.cdc.gov.2 November 2018.Retrieved6 December2021.
- ^"n- HEPTANE"(PDF).
