Question

How do the prefixes and suffixes for the open chain hydrocarbons indicate their formula?

Answer 1

In open chain hydrocarbon, the procedure of IUPAC nomencleature explains that ;

an IUPAV name of a compound consists of three parts 1. word root 2. Suffix 3. Prefix;

• word root is the basic unit of name which denotes the no. of carbon atoms present in principal chain as for ex; for compound, C₂H₅OH; the word root is ETH( eth means two carbon corresponds to ethane)
• Suufix is used at the end of name; which may be of two types a) primary suffix; which explains saturation of carbon chain as "ane" for alkanes, ene for alkenes etc. while b) secondary suffix; which explains functional group as -ol for alcohol, -al for aldehydes etc.
• prefix is used in alphabatic order to denote side chain or substituent group in the compound. It is added before word root. for ex; cyclo if cyclic gr. is attached, halo if halogen is attached etc.

Thus the name is followed as= prefix-word root-suffix. Thus, the name of C₂H₅OH becomes; Ethanol [(eth(word root) ane(primary suffix) ol (secondary suffix)]

Hence without prefixes and suffixes we cant identify the name of compounds.

For ex; In Cl-CH₃ the IUPAC name is ; Prefix(Chloro) word root (meth) suffix (ane)

The name is Chloromethane.