Example of haloalkenes in structere formula
Answers
Alkanes are one of the simplest types of organic compounds and consist only of carbon and hydrogen atoms linked together exclusively by single bonds (i.e. alkanes are saturated hydrocarbons). Haloalkanes are similar to alkanes but one or more of the hydrogen atoms in the corresponding alkane is replaced by a halogen atom(s) in the haloalkane.
What are halogens ?
Halogens are the elements in Group 7 (Group VII) of the periodic table, specifically: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At). The halogens most commonly found in, and of greatest importance in organic chemistry, are fluorine, chlorine, bromine and iodine.
Is there a general formula for haloalkanes ?
A simple general formula that describes many (but not all) of the haloalkanes usually included in basic chemistry courses is :
CnH2n+1X
where the letter n represents the number of carbon atoms in each molecule of the compound and the letter X represents a particular halogen atom. An example of a real chemical described by this formula is fluoromerhane (also known as methyl fluoride), whose molecules have just one carbon atom (so n=1) and includes the halogen fluorine (so X=F), hence it has the chemical formula CH3F.
Examples of Haloalkanes
The simplest way to convey what haloalkanes are and how they differ from alkanes is using molecular diagrams of some simple haloalkanes together with the corresponding alkane, for comparison. (The names of the chemicals whose structures are shown below are explained further down this page.)
Example of Haloalkane
Corresponding Alkane
1
Fluoromethane
(also known as methylfluoride and as methyl fluoride)
fluoromethane
Methane
methane
2
Bromoethane
(also known as
ethyl bromide)
bromoethane
Ethane
ethane
3
Chloropropane
(also known as
1-chloropropane)
chloropropane
Propane
propane
4
Iodobutane
(also known as
1-iodobutane and as
n-butyl iodide)
iodobutane
Butane
butane
The above molecular structures have been drawn was simply as possible.
In all cases it is easy to see that the hydrogen atom represented by the H on the extreme right-hand-side of the alkane on the right has been replaced by the halogen atom in each of the haloalkanes on the left. As indicated by these examples, simple haloalkanes are named according to the specific halogen element (F, Cl, Br or I) in the molecule and the number of carbon atoms (using the same system of naming as applies to alkanes). More information about structures, names and classification of haloalkanes follows below.
The simple molecular structures shown above all represent the halogen atoms as being located on the right-hand-side of the molecule. This is just to make clear the pattern and difference between these haloalkanes and their corresponding linear alkanes. In the case of halomethanes and haloethanes, all the possible positions at which the halogen atom may be attached to the rest of the molecule are equivalent, that is - there is only one structural isomer of halomethanes and haloethanes.
This is shown in the following diagrams of the possible ways of drawing the four halomethane molecules CH3F, CH3Cl, CH3Br and CH3I.
Alkanes are one of the simplest types of organic compounds and consist only of carbon and hydrogen atoms linked together exclusively by single bonds (i.e. alkanes are saturated hydrocarbons). Haloalkanes are similar to alkanes but one or more of the hydrogen atoms in the corresponding alkane is replaced by a halogen atom(s) in the haloalkane.
What are halogens ?
Halogens are the elements in Group 7 (Group VII) of the periodic table, specifically: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At). The halogens most commonly found in, and of greatest importance in organic chemistry, are fluorine, chlorine, bromine and iodine.
Is there a general formula for haloalkanes ?
A simple general formula that describes many (but not all) of the haloalkanes usually included in basic chemistry courses is :
CnH2n+1X
where the letter n represents the number of carbon atoms in each molecule of the compound and the letter X represents a particular halogen atom. An example of a real chemical described by this formula is fluoromerhane (also known as methyl fluoride), whose molecules have just one carbon atom (so n=1) and includes the halogen fluorine (so X=F), hence it has the chemical formula CH3F.
Examples of Haloalkanes
The simplest way to convey what haloalkanes are and how they differ from alkanes is using molecular diagrams of some simple haloalkanes together with the corresponding alkane, for comparison. (The names of the chemicals whose structures are shown below are explained further down this page.)
Example of Haloalkane
Corresponding Alkane
1
Fluoromethane
(also known as methylfluoride and as methyl fluoride)
fluoromethane
Methane
methane
2
Bromoethane
(also known as
ethyl bromide)
bromoethane
Ethane
ethane
3
Chloropropane
(also known as
1-chloropropane)
chloropropane
Propane
propane
4
Iodobutane
(also known as
1-iodobutane and as
n-butyl iodide)
iodobutane
Butane
butane
The above molecular structures have been drawn was simply as possible.
In all cases it is easy to see that the hydrogen atom represented by the H on the extreme right-hand-side of the alkane on the right has been replaced by the halogen atom in each of the haloalkanes on the left. As indicated by these examples, simple haloalkanes are named according to the specific halogen element (F, Cl, Br or I) in the molecule and the number of carbon atoms (using the same system of naming as applies to alkanes). More information about structures, names and classification of haloalkanes follows below.
The simple molecular structures shown above all represent the halogen atoms as being located on the right-hand-side of the molecule. This is just to make clear the pattern and difference between these haloalkanes and their corresponding linear alkanes. In the case of halomethanes and haloethanes, all the possible positions at which the halogen atom may be attached to the rest of the molecule are equivalent, that is - there is only one structural isomer of halomethanes and haloethanes.
This is shown in the following diagrams of the possible ways of drawing the four halomethane molecules CH3F, CH3Cl, CH3Br and CH3I.