Reactive surfactant composition for emulsion polymerization

A method of producing a reactive anionic surfactant, comprising the following steps (i) to (iii), the reactive anionic surfactant being represented by the following formula (1) and being satisfied with the following requirement R (provided that in the requirement R, when n is 0, then the step (ii) is not performed):

• Step (i):
• a step of adding an alkylene oxide having a carbon number of 4 or more and 18 or less to a compound represented by the following formula (2) in the presence of an aluminum-magnesium complex oxide catalyst to thereby obtain a compound represented by the following formula (3);
• Step (ii):
• a step of adding ethylene oxide to the compound represented by the following formula (3) in the presence of an alkali catalyst to thereby obtain a compound represented by the following formula (4);
• and
• Step (iii):
• a step of sulfating the compound represented by the following formula (4) with a sulfating agent and neutralizing with a basic substance:
• wherein AO represents an alkyleneoxy group having a carbon number of 4 or more and 18 or less;
• EO represents an ethyleneoxy group;
• p represents an integer of 1 or more and 15 or less;
• m′ represents an integer of 0 or more;
• n′ represents an integer of 0 or more;
• M+ represents a hydrogen ion or a cation;
• and plural kinds of AOs may coexist:
• and
• Requirement R:
• an average addition molar number m of AO is a number of 1 or more and 50 or less;
• an average addition molar number n of EO is a number of 0 or more and 200 or less;
• and when in the compound represented by the formula (1) (component A), a component having an addition molar number of AO of (m−3) or less is defined as (component A-1), and a component having an addition molar number of AO of (m+2) or more is defined as (component A-2), X in the following formula (I) is less than 30, provided that when m is less than 3, (m′=0) is defined as (component A-1):
• X={(molar number of componentA-1)+(molar number of componentA-2)}÷(molar number of componentA)×100 (I).