Primary is a term used in organic chemistry to classify various types of compounds (e.g. alcohols, alkyl halides, amines) or reactive intermediates (e.g. alkyl radicals, carbocations).
| Red highlighted central atoms in various groups of chemical compounds. Primary central atoms compared with secondary, tertiary and quaternary central atoms. | ||||
| primary | secondary | tertiary | quaternary | |
| Carbon atom in an alkane | 
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| Alcohol | 
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does not exist |
| Amine | 
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| Amide | 
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does not exist |
| Phosphine | 
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