Aromatic amines have the nitrogen atom connected to an aromatic ring. Mechanisms differ for aliphatic and aromatic aldehydes and for aromatic and aliphatic phosphonium ylides. Laccases catalyze ring cleavage of aromatic compounds. It ignites readily, burning with a smoky flame characteristic of aromatic compounds. An alternative to aromatic substitution is electrophilic aliphatic substitution. It is left on a slow fire or dum for a fragrant and aromatic flavour. Phenols are highly susceptible to Electrophilic aromatic substitutions. Toluene reacts as a normal aromatic hydrocarbon in electrophilic aromatic substitution. Metallointercalators are complexes of a metal cation with polycyclic aromatic ligands. Pakistani dishes are known for having aromatic and sometimes spicy flavors. Shale oil usually contains large quantities of olefinic and aromatic hydrocarbons. Thiols, and sulfides can be removed from aliphatic, aromatic, or heteroaromatic compounds. Amygdalin is a cyanogenic glycoside derived from the aromatic amino acid phenylalanine. Growing there are rare and exotic medicinal and aromatic plants. Mints are aromatic, almost exclusively perennial herbs.