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A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact, and thus greater van der Waals forces, between adjacent molecules. For example, compare isobutane (2-methylpropane) and n-butane (butane), which boil at −12 and 0 °C, and 2,2-dimethylbutane and 2,3-dimethylbutane ...
The following is a list of straight-chain alkanes, the total number of isomers of each (including branched chains), and their common names, sorted by number of carbon atoms. [ 1 ] [ 2 ] Number of C atoms
There are also a large number of branched or ring alkanes that have specific names, e.g., tert-butyl, bornyl, cyclohexyl, etc. There are several functional groups that contain an alkene such as vinyl group, allyl group, or acrylic group. Hydrocarbons may form charged structures: positively charged carbocations or negative carbanions.
It is defined [8] as = where s b is the mean square radius of gyration of the branched macromolecule in a given solvent, and s l is the mean square radius of gyration of an otherwise identical linear macromolecule in the same solvent at the same temperature. A value greater than 1 indicates an increased radius of gyration due to branching.
This is because the bond angle for an alkene, C-C=C, is 122°, while the bond angle for an alkane, C-C-C, is 112°. When these carbons form a small ring, the alkene which has a larger bond angle will have to compress more than the alkane causing more bond angle strain. [4] Cycloalkenes have a lower melting point than cycloalkanes of the same size.
Isocetane (2,2,4,4,6,8,8-heptamethylnonane) is a highly branched alkane used as a reference in determining the cetane number of diesel. It has a cetane number of 15. [ 2 ] Isocetane replaced 1-methylnaphthalene in 1962 as the lower reference for cetane number (1-methylnaphthalene has cetane number zero) owing to the oxidation instability and ...
In general, straight-chain alkanes are converted to branched isomers by heating in the presence of a catalyst. Examples include isomerisation of n-butane to isobutane and pentane to isopentane. Highly branched alkanes have favorable combustion characteristics for internal combustion engines. [2] Further examples are the Wagner–Meerwein ...
Heptane or n-heptane is the straight-chain alkane with the chemical formula H 3 C(CH 2) 5 CH 3 or C 7 H 16.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).