• First three alkanes – methane, ethane and propane have only one structure but higher alkanes can have more than one structure.
• For eg. four carbon atoms of `color{red}(C_4 H_(10))` can be joined either in a continuous chain or with a branched chain in the following two ways :
• Different arrangements of `color{red}(C_5 H_(12)):`
• Structures I and II possess same molecular formula but differ in their boiling points and other properties.
• Similarly structures III, IV and V possess the same molecular formula but have different properties.
• Structures I and II are isomers of butane, whereas structures III, IV and V are isomers of pentane.
• Since difference in properties is due to difference in their structures, they are known as structural isomers.
• Structures I and III have continuous chain of carbon atoms but structures II, IV and V have a branched chain.
Such structural isomers which differ in chain of carbon atoms are known as chain isomers. `color{red}(C_4H_(10))` and `color{red}(C_5H_(12))` have two and three chain isomers respectively.
`color{red}("Based upon the number of carbon atoms attached to a carbon atom, the carbon atom")` `color{red}(" is termed as primary (1°), secondary ((2°)")`, `color{red}("tertiary (3°) or quaternary (4°)")`.
• Carbon atom attached to no other carbon atom as in methane or to only one carbon atom as in ethane is called primary carbon atom. Terminal carbon atoms are always primary.
• Carbon atom attached to two carbon atoms is known as secondary.
• Tertiary carbon is attached to three carbon atoms.
• Neo or quaternary carbon is attached to four carbon atoms.
• First three alkanes – methane, ethane and propane have only one structure but higher alkanes can have more than one structure.
• For eg. four carbon atoms of `color{red}(C_4 H_(10))` can be joined either in a continuous chain or with a branched chain in the following two ways :
• Different arrangements of `color{red}(C_5 H_(12)):`
• Structures I and II possess same molecular formula but differ in their boiling points and other properties.
• Similarly structures III, IV and V possess the same molecular formula but have different properties.
• Structures I and II are isomers of butane, whereas structures III, IV and V are isomers of pentane.
• Since difference in properties is due to difference in their structures, they are known as structural isomers.
• Structures I and III have continuous chain of carbon atoms but structures II, IV and V have a branched chain.
Such structural isomers which differ in chain of carbon atoms are known as chain isomers. `color{red}(C_4H_(10))` and `color{red}(C_5H_(12))` have two and three chain isomers respectively.
`color{red}("Based upon the number of carbon atoms attached to a carbon atom, the carbon atom")` `color{red}(" is termed as primary (1°), secondary ((2°)")`, `color{red}("tertiary (3°) or quaternary (4°)")`.
• Carbon atom attached to no other carbon atom as in methane or to only one carbon atom as in ethane is called primary carbon atom. Terminal carbon atoms are always primary.
• Carbon atom attached to two carbon atoms is known as secondary.
• Tertiary carbon is attached to three carbon atoms.
• Neo or quaternary carbon is attached to four carbon atoms.