Ionic liquid, lubricant, and magnetic recording medium

An ionic liquid comprising:

• a conjugate acid (B+);
• and
• a conjugate base (X−),
• wherein the ionic liquid is represented by the following general formula (1) and is protic, and
• wherein the conjugate base is a conjugate base of sulfonic acid, a conjugate base of sulfonimide, or a conjugate base of trisulfonylmethide:
• where R1 and R2 each represent a hydrogen atom or R1 and R2 form a benzene ring together with carbon atoms to which R1 and R2 are bonded, R3 represents a straight-chain hydrocarbon group having 10 or more carbon atoms, and R4 represents a hydrogen atom in the general formula (1).

An ionic liquid comprising:

• a conjugate acid (B+);
• and
• a conjugate base (X−),
• wherein the ionic liquid is represented by the following general formula (Y) and is protic, and
• wherein the conjugate base is a conjugate base of sulfonic acid, a conjugate base of sulfonimide, or a conjugate base of trisulfonylmethide