Claisen may refer to:
*
Rainer Ludwig Claisen, a German chemist
**
Claisen rearrangement, a reaction of a allyl vinyl ether to a γ,δ-unsaturated carbonyl
**
Claisen condensation, a reaction between esters and carbonyl compounds in the presence of a strong base
**
Ireland–Claisen rearrangement, a chemical reaction of an allylic ester with strong base
**
Claisen isatin synthesis
See also
*
5243 Clasien
5 (five) is a number, numeral and digit. It is the natural number, and cardinal number, following 4 and preceding 6, and is a prime number. It has attained significance throughout history in part because typical humans have five digits on each ...
, a minor planet
{{Disambig