Many additional routes exist for resorcinol. It can be produced when any of a large number of resins (such as galbanum and asafoetida) are melted with potassium hydroxide, or by the distillation of Brazilwood extract. It may be prepared synthetically by melting 3-iodophenol, phenol-3-sulfonic acid, or benzene-1,3-disulfonic acid with potassium carbonate; by the action of nitrous acid on 3-aminophenol or on 1,3-diaminobenzene. Many "ortho"- and "para"-compounds of the aromatic series (for example, the bromophenols, benzene-"para"-disulfonic acid) also yield resorcinol on fusion with potassium hydroxide.