 | |
 | |
 | |
| Names | |
|---|---|
| Preferred IUPAC name Heptane[2] | |
| Other names Septane[1] | |
| Identifiers | |
| |
3D model (JSmol) | |
| 1730763 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| EC Number |
|
| 49760 | |
| MeSH | n-heptane |
| RTECS number |
|
| UNII | |
| UN number | 1206 |
| |
| |
| Properties | |
| C7H16 | |
| Molar mass | 100.205 g·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) |
Henry's law constant (kH) | 12 nmol Pa−1 kg−1 |
| −85.24·10−6 cm3/mol | |
Refractive index (nD) | 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 |
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 | |
| GHS labelling: | |
    | |
| 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 dose or 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 | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Heptane orn-heptane is the straight-chainalkane with thechemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component inanti-knock test engines, a 100% heptane fuel is the zero point of theoctane 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 forgasoline (petrol) dispensed globally.
Normal heptane was discovered in 1862 byCarl Schorlemmer, who, while analyzing pyrolysis products of thecannel coal mined inWigan, identified, separated byfractional distillation and studied a series of liquid hydrocarbons inert tonitric andsulfuric acids. One of them, which he calledhydride ofheptyl (oenanthyl), had anempirical formula of C7H16, density of 0.709 at 18 °C and boiled between 98 and 99 °C.[7] In the next year he identified the same compound in thePennsylvanian oil.[8] By 1872 he switched his nomenclature to the modern one.[9]
During theAmerican Civil War and shortly thereafter Californians discovered that some pines gaveturpentine with unusual properties. It took until 1879 to identify heptane as the cause of that (see below for details), and only by the end of the century was this fact accepted by Europeanchemists.[10]
Heptane and its many isomers are widely used inlaboratories as a non-polarsolvent.[11] It is often preferred tohexane due to heptane being comparatively less toxic and less volatile.[12] 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]
Aqueousbromine may be distinguished from aqueousiodine by its appearance afterextraction into heptane. In water, both bromine and iodine appearbrown. However, iodine turnspurple when dissolved in heptane, whereas the bromine solution remains brown.
Heptane is commercially available as both pure and mixed isomers for use in paints and coatings, as therubber cement solvent "Bestine",[13] 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.[14][15]
Heptane is also used as anadhesive remover bystamp collectors. Since 1974, theUnited States Postal Service has issuedself-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 aslimonene-based products, have become popular solvents for removing stamps more easily.[16]
n-Heptane is defined as the zero point of theoctane rating scale. It is a lighter component ingasoline and burns moreexplosively, causingengine pre-ignition (knocking) in its pure form, as opposed tooctane 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 purityn-heptane, unmixed with other isomers of heptane or other alkanes, distilled from theresin ofJeffrey pine and 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.
Heptane has nineisomers, or eleven ifenantiomers are counted:
The linearn-heptane can be obtained fromJeffrey pine oil.[18] The six branched isomers without a quaternary carbon can be prepared by creating a suitable secondary or tertiaryalcohol by theGrignard reaction, converting it to analkene bydehydrogenation, andhydrogenating the latter.[18] The 2,2-dimethylpentane isomer can be prepared by reactingtert-butyl chloride withn-propyl magnesium bromide.[18] The 3,3-dimethylpentane isomer can be prepared fromtert-amyl chloride and ethyl magnesium bromide.[18]
Acute exposure to heptane vapors can causedizziness, stupor, incoordination, loss of appetite, nausea, dermatitis, chemical pneumonitis, unconsciousness, or possible peripheral neuropathy.[19]
In aCDC study, it was found that prolonged exposure to heptane may also cause a state ofintoxication and uncontrolled hilarity in some participants and astupor lasting for 30 minutes after exposure for others.[20] Prolonged exposure can also lead toskin dryness or cracking, since the substance defats skin.[21]
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 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, and reduced coordination due to its effects on the nervous system.[22]
| Route | Side Effects | First Aid Procedure |
|---|---|---|
| Ingestion | Nausea, diarrhea, headache, stomach pain, intoxication, heart failure | Seek medical attention |
| Eye Contamination | Irritation | Immediate irrigation |
| Skin Contamination | Irritation, dermatitis; can be absorbed and produce similar effects to inhalation | Immediate wash with soap |
| Inhalation | Irritation, coughing, difficulty breathing, headache, drowsiness, dizziness, unconsciousness, coma, death | Respiratory support |
| International | |
|---|---|
| National | |
| Other | |
