Patent ID: 7696347

Claim:
A compound represented by following formula I: wherein M represents an alkali metal, N(R 1 )(R 2 )(R 3 )(R 4 ) or P(R 1 )(R 2 )(R 3 )(R 4 ) in which R 1 , R 2 , R 3 and R 4 each independently represents a C 1-6 alkyl group or a C 7-15 aralkyl group, provided that M forms a counterion with an anion in a molecule; X represents a C 1-6 alkyl group optionally having 1 to 3 groups selected from a following group A, a C 3-8 cycloalkyl group optionally having 1 to 3 groups selected from a following group A, a 5- to 6-membered non-aromatic heterocyclic group optionally having 1 to 3 groups selected from a following group Z, or R 5 C(═O) in which R 5 represents a hydrogen atom, a C 1-6 alkyl group or a C 3-8 cycloalkyl group; the group A represents an amino group optionally having a C 1-6 alkyl group or a C 3-8 cycloalkyl group, a hydroxy group, a C 1-6 alkyl group, a C 3-8 cycloalkyl group, a C 1-6 alkoxy group, a C 3-8 cycloalkoxy group, and 5- to 6-membered non-aromatic heterocyclic group optionally having 1 to 3 groups selected from the following group Z; the group Z represents a C 1-6 alkyl group or a C 1-6 alkoxycarbonyl group; m represents an integer of 0 or 1; k represents an integer of 0 or 1.