(Solid + liquid) equilibria and solid compound formation in (N-methyl-2-pyrrolidinone + benzene, or toluene, or 1,3,5-trimethylbenzene, or ethylbenzene, or chlorobenzene, or 1,2-dichlorobenzene, or 1,2,4-trichlorobenzene, or 1,1,1-trichloroethane, or dichloromethane)