preferred_name: 1-hexadecanoyl-2-heptanoyl-sn-glycero-3-phosphocholine + 1-heptanoyl-2-hexadecanoyl-sn-glycero-3-phosphocholine => 1,2-diheptanoyl-sn-glycero-3-phosphocholine + 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine