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.
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 amount and location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane is used as one of the standard values in the octane rating scale.
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.
An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates gasoline's capability against compression.
Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH3)3. It is an isomer of butane. Isobutane is a colorless, odorless gas. It is the simplest alkane with a tertiary carbon atom. Isobutane is used as a precursor molecule in the petrochemical industry, for example in the synthesis of isooctane.
Methyl tert-butyl ether (MTBE), also known as tert-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water. Primarily used as a fuel additive, MTBE is blended into gasoline to increase its octane rating and knock resistance, and reduce unwanted emissions.
Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene. Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents.
Butene, also known as butylene, is an alkene with the formula C4H8. The word butene may refer to any of the individual compounds. They are colourless gases that are present in crude oil as a minor constituent in quantities that are too small for viable extraction. Butene is therefore obtained by catalytic cracking of long-chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products, and the butene is extracted from this by fractional distillation.
Isobutylene is a hydrocarbon with the chemical formula (CH3)2C=CH2. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value.
Pentenes are alkenes with the chemical formula C
5H
10. Each molecule contains one double bond within its molecular structure. Six different compounds are in this class, differing from each other by whether the carbon atoms are attached linearly or in a branched structure and whether the double bond has a cis or trans form.
Cumene (isopropylbenzene) is an organic compound that contains a benzene ring with an isopropyl substituent. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to cumene hydroperoxide, which is an intermediate in the synthesis of other industrially important chemicals, primarily phenol and acetone.
1-Propanol is a primary alcohol with the formula CH3CH2CH2OH and sometimes represented as PrOH or n-PrOH. It is a colourless liquid and an isomer of 2-propanol. It is formed naturally in small amounts during many fermentation processes and used as a solvent in the pharmaceutical industry, mainly for resins and cellulose esters, and, sometimes, as a disinfecting agent.
2,4-Dimethyl-6-tert-butylphenol is the organic compound with the formula Me2(tert-Bu)C6H2OH (Me = methyl, tert-Bu = tertiary butyl). It is a colorless oil that is classified as an alkylated phenol.
An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs. The mixture known as gasoline or petrol, when used in high compression internal combustion engines, has a tendency to knock and/or to ignite early before the correctly timed spark occurs.
Tripropylene, also known as propylene trimer, is usually sold as a mixture of structural isomers of nonene. This mixture is obtained by oligomerization of propene:
An alkylation unit (alky) is one of the conversion processes used in petroleum refineries. It is used to convert isobutane and low-molecular-weight alkenes (primarily a mixture of propene and butene) into alkylate, a high octane gasoline component. The process occurs in the presence of an acid such as sulfuric acid (H2SO4) or hydrofluoric acid (HF) as catalyst. Depending on the acid used, the unit is called a sulfuric acid alkylation unit (SAAU) or hydrofluoric acid alkylation unit (HFAU). In short, the alky produces a high-quality gasoline blending stock by combining two shorter hydrocarbon molecules into one longer chain gasoline-range molecule by mixing isobutane with a light olefin such as propylene or butylene from the refinery's fluid catalytic cracking unit (FCCU) in the presence of an acid catalyst.
2,4-Dimethylpentane is an alkane with the chemical formula [(H3C)2CH]2CH2. This colorless hydrocarbon is produced in large quantities in oil refineries. It results from the alkylation of isobutane by propylene. Often referred to as "alkylate", it is blended with other gasoline components to give a high octane fuel. Unlike n-heptane, 2,4-dimethylpentane is a desirable fuel because its branched structure allows combustion without knocking.
4-Ethyltoluene is an organic compound with the formula CH3C6H4C2H5. It is one of three isomers of ethyltoluene, the other two isomers being 3-ethyltoluene and 2-ethyltoluene. All are colorless liquids and all are used for the production of specialty polystyrenes.
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.
The diisopropylbenzenes(DIPB) are organic compounds with the formula C6H4(CH(CH3)2)2. Three isomers exist: 1,2- 1,3-, and 1,4-diisopropylbenzene. All are colorless liquids, immiscible in water, with similar boiling points. They are classified are aromatic hydrocarbons bearing a pair of isopropyl (CH(CH3)2) substituents. DIPB has been referred to as "a common diluent" alongside hexane.
