The present invention relates to a method for alkylating a molecule or an ion, wherein the molecule or the ion is alkylated by reacting it with an alkylating agent, wherein the alkylating agent is a compound according to formula (1). In the formula (1), R 1 is a substituted or unsubstituted C 1-20 hydrocarbon residue or a polymer, R 2 is a substituted or unsubstituted C 1-20 hydrocarbon residue or a hydrogen atom, R 3 is absent, a substituted or unsubstituted C 1-20 hydrocarbon residue or a hydrogen atom, R 4 and R 5 are linked with each other to form an aromatic group or are independently from each other selected from the group consisting of a hydrogen atom, substituted and unsubstituted C 1-20 hydrocarbon residues and electron withdrawing groups, X 1 is an oxygen atom, a nitrogen atom or a sulfur atom, wherin R 3 is not present in formula (1) if X 1 is an oxygen atom or a sulfur atom, Z is a covalent bond or an aromatic group and A - is an anion.