what is the normal substituents and complex substituents?? Explained with examples!!
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The list of common alkyl substituents is quite short and it is therefore quite limited in its scope. In order to deal with other substituents (but it can also be applied to the common branched substituents too), there is a methodology for dealing with more complex substituents. This essentially involves treating the substituent as if it were a molecule on its own, see below.
For the substituent:
determine the point of attachment to the chain that defines the parent root (i.e. the longest continuous chain)
the first carbon in the substituent is regarded as the C1 of the substituent
from C1, find the longest continuous chain originating from C1 - this is the root for the substituent.
identify any substituents off this chain
list these alphabetically with appropriate multipliers
insert locants as required remembering that the point of attachment is defined as C1.
Now include this "complex" substituent in the overall name...
the complex substituent appears in brackets proceeded by its locant
the complex substituent is alphabetised based on the first letter of the name in the bracket : this includes the multiplier e.g. di
this is because the term in brackets is the name of the whole complex substituent and not several substituents.
syntax: locant numbers separated from letters by hyphens, e.g. 1-methyl, locant numbers from locant numbers by commas e.g. 1,1-dimethyl, no spaces.
Consider the following examples:
First work out the name of the complex substituent - this is shown in bold in the figure:
The longest chain in the substituent is C3 therefore it's a propyl substitent
There is one substituent off this chain, a C1 alkyl group i.e. a methyl group
The methyl group is on C2 on the complex substituent
Complex substituent name : 2-methylpropyl
complex substituent
Now work on the whole structure:
Functional group is an alkane, therefore suffix = -ane
The ring structure is C6 therefore root = hex
There is one substituent:
a complex substituent (see above) = (2-methylpropyl)
Note the syntax: no space or hypen to separate the letters of the substituent and parent root.
(2-methylpropyl)cyclohexane
For the substituent:
determine the point of attachment to the chain that defines the parent root (i.e. the longest continuous chain)
the first carbon in the substituent is regarded as the C1 of the substituent
from C1, find the longest continuous chain originating from C1 - this is the root for the substituent.
identify any substituents off this chain
list these alphabetically with appropriate multipliers
insert locants as required remembering that the point of attachment is defined as C1.
Now include this "complex" substituent in the overall name...
the complex substituent appears in brackets proceeded by its locant
the complex substituent is alphabetised based on the first letter of the name in the bracket : this includes the multiplier e.g. di
this is because the term in brackets is the name of the whole complex substituent and not several substituents.
syntax: locant numbers separated from letters by hyphens, e.g. 1-methyl, locant numbers from locant numbers by commas e.g. 1,1-dimethyl, no spaces.
Consider the following examples:
First work out the name of the complex substituent - this is shown in bold in the figure:
The longest chain in the substituent is C3 therefore it's a propyl substitent
There is one substituent off this chain, a C1 alkyl group i.e. a methyl group
The methyl group is on C2 on the complex substituent
Complex substituent name : 2-methylpropyl
complex substituent
Now work on the whole structure:
Functional group is an alkane, therefore suffix = -ane
The ring structure is C6 therefore root = hex
There is one substituent:
a complex substituent (see above) = (2-methylpropyl)
Note the syntax: no space or hypen to separate the letters of the substituent and parent root.
(2-methylpropyl)cyclohexane
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