Generally speaking, completely aliphatic quaternary ammonium compounds appear to provide optimal antimicrobial activity when the largest aliphatic group is a straight chain C16 18 group and benzyl quaternary ammonium compounds appear to provide {HEAD ~ optimal antimicrobial activity} when {TAIL ~ the largest aliphatic group} is a straight chain C14 group 
Generally speaking , completely aliphatic quaternary ammonium compounds appear to provide optimal antimicrobial activity when the largest aliphatic group is a straight chain C16 18 group and benzyl quaternary ammonium compounds appear to provide { HEAD ~ optimal antimicrobial activity } when { TAIL ~ the largest aliphatic group } is a straight chain C14 group
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