Science Fair Project Encyclopedia
An alkyl is a functional group of an organic chemical that contains only carbon and hydrogen atoms, which are arranged in a chain. They have general formula CnH2n+1. Examples include methyl CH3* (derived from methane) and butyl C2H5 (derived from butane). They are not found on their own but are found attached to other hydrocarbons.
The naming convention for alkyls is much the same as alkanes. The suffix is always -yl. The prefix depends on how many carbon atoms are in the molecule. This uses the same system as for Alkanes as shown in this table (taken from IUPAC nomenclature):
|Number of carbons||1||2||3||4||5||6||7||8||9||10||11||12|
For example, the first three alkyls are called Methyl, Ethyl and Propyl.
The structure of an alkyl is the same as its straight chained alkane counterpart but with one too few hydrogen atoms. For example, this is the structure of Methyl, the smallest alkyl:
Alkyls are normally found as part of larger structures and are usually represented by shorthand in general formulas using the symbol R. This is shown in the general displayed formula of an ester below:
R is used to represent an alkyl (any alkyl) and R' is used to represent another alkyl that is not necessarily the same as the first alkyl. It is common practice to add another ' to the R when outlining structures with more alkyl groups. For example if a structure had many alkyl groups, each group could be represented by R, R', R'' and so on.
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