Alkyl Groups and Branched hydrocarbons

CH3-CH2-CH-CH2-CH2-CH3
        |
        CH2
        |
        CH3
This attached "groups" are called Alkyl Groups.(from textbook)
What is an alkyl group?
An Alkyl Group is an alkane which has lost one hydrogen atom. (textbook)


Example: CH3-CH-CH3  (Alkane group)
             |
             CH3     (Alkyl group)
What's so special? Alkane <lose H> Alkyl(naming:change "ane" to "yl")
So? : CH3-(methyl) CH3-CH2-(ethyl)

Rule: An alkyl group is named by changing the "ane" ending of the original hydrocarbon to "yl". (textbook)
(textbook)
Original hycarbon
Alkyl group
methane=CH4
methyl=CH3-
ethane=CH3-CH3
ethyl+CH3-CH2-
propane=CH3-CH2-CH3
propyl=CH3-CH2-CH2-
butane=CH3-CH2-CH2-CH3
butyl=CH3-CH2-CH2-CH2-


Branched Hydrocarbon(Substituted Hydrocarbon):The resulting molecule when an alkyl group is attached to another hydrocarbon. (textbook)
Branched hydrocarbons=alkane group+alkyl groups
rule:the first step in naming a branched hydrocarbon is to find the longest continuous chain of carbon atoms. The longest chain is called"parent" chain. (textbook)

How to find "parent" chain ?
* The turning point where we have more than two options.
Naming:
Rule: A substituted hydrocarbon is named by writing the following one after another
1)the carbon number at which the alkyl group is attached,
2)a dash,
3)the name of the alkyl group,and finally
4)the name of the longest hydrocarbon chain, to which the alkyl group is attached.
(textbook)

Note: The carbon atoms in the parent hydrocarbon are numbered consecutively from the end of the hydrocarbon which gives the
Lowest Possible Set of Numbers to the attached groups. (textbook)

The above rule of naming in my own words:
1) Find the parent chain
2) Count the numbers of carbons, it's alkane, and write the alkane group at the end of the name.
3) Find the alkyl group, and write the position of the alkyl group by using a dash to attach the alkyl group.
4)Rember, count the lowest number of the position, and there's no space between alkyl and alkane group.

Example: CH3-CH-CH2-CH3         3)[branch]2)[alkyl] 1)[alkane]             |
             CH3                  2-methylbutane

Rule: If more than one Different alkyl group is attached to a hydrocarbon, then
1)list the alkyl groups
alphabetically,
2)precede each alkyl group by its number, and
3)put a dash between each alkyl group and its number.


The above rule of naming in my own words:If more than one Different alkyl group is attached to a hydrocarbon, then
1) List the alkyl groups in order(for example:methyl and ethyl, put ethyl before methyl because e is before m)
2) Put each alkyl group's number(position) in front of them
3) Put a dash between each alkyl group and its number

Example: 1   2  3   4  5   6   7   8         CH3-CH-CH2-CH-CH2-Ch2-CH2-CH3
             |      |             CH3    CH2-CH3
              4-ethyl-2-methyloctane(alphabetically, e is before m)

Rule:If an alkyl group is repeated, then
1)list each carbon number where the repeated group is attached, separated by commas,and
2)prefix the repeated group name by di, tri, tetra,etc. to show how many identical groups are attached.(textbook)

The above rule of naming in my own words:If an alkyl group is repeated, then
1) List the positions of carbons which the repeated alkyl groups are attached,using commas to separate the numbers
2) Put di, tri, tetra, etc, to show how many groups are attached

Example: 1   2  3   4  5   6  7   8         CH3-CH-CH2-CH-CH2-CH-CH2-CH3
             |      |      |             CH3    CH3    CH3
         2,4,6-trimethyloctane(3 methyl where locate at the positions of 2,4 and 6)


Tips:
How to check your diagram:
Carbon can only have four bonds (can be either alkane, alkyl, or hydrogen)