Addition Reaction

A general type of chemical reaction between two compounds, A and B, such that there is a net reduction in bond multiplicity (e.g., addition of a compound across a carbon-carbon double bond such that the product has lost this ff-bond). An example is the hydration of a double bond, such as that observed in the conversion of fumarate to malate by fumarase. Addition reactions can also occur with strained ring structures that, in some respects, resemble double bonds (e.g., cyclopropyl derivatives or certain epoxides). A special case of a hydro-alkenyl addition is the conversion of 2,3-oxidosqualene to dammara-dienol or in the conversion of squalene to lanosterol. Reactions in which new moieties are linked to adjacent atoms (as is the case in the hydration of fumarate) are often referred to as 1,2-addition reactions. If the atoms that contain newly linked moieties are not adjacent (as is often the case with conjugated reactants), then the reaction is often referred to as a 1,n-addition reaction in which n is the numbered atom distant from 1 (e.g., 1,4-addition reaction). In general, addition reactions can take place via electrophilic addition, nucleo-philic addition, free-radical addition, or via simultaneous or pericyclic addition.

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