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In chemistry, the suffix -al is the IUPAC nomenclature used in organic chemistry to form names of aldehydes containing the -(CO)H group in the systematic form. It was extracted from the word "aldehyde". With the exception of chemical compounds having a higher priority than it, all aldehydes is named with -al, such as 'propanal'. Some aldehydes also have common names, such as formaldehyde for methanal, acetaldehyde for ethanal. Benzaldehyde does not have a systematic form with -al.