Morpholinium bisulfate [morH][HSO4]: An efficient and reusable catalyst for the synthesis of bis(indolyl)methanes

Morpholinium bisulfate [morH][HSO4] ionic liquid was found to be an effective catalyst for the condensation reaction of indoles with carbonyl compound at room temperature. Present methodology has several merits such as mild reaction condition, inexpensive catalyst, stable at room temperature and it was also found that this catalyst could be recovered quantitatively and reused without much loss of catalytic activity.