Strong, moderate, and weak nucleophiles can be categorized as follows: A strong nucleophile contains more unsaturation, such as a double bond or triple bond, or it may be a cyclic structure. Strong nucleophiles may contain atoms with higher electronegativity, or atoms having loosely bound electron pairs. Each of these characteristics make the species more electron rich, which makes it more effective in attacking an electrophilic carbon atom. Moderate nucleophiles are those that increase the avai