3, 3-Dimethylnaphthidine is a polycyclic aromatic hydrocarbon, being one kind of dimethylnaphthidine isomers. It is a useful indicator for metal titration (for example, the titration of aluminum using EDTA method, determination of vanadium). It has also been used for the photometric determination of small amount of oxygen as well as chlorine in water.
https://en.wikipedia.org/wiki/2,6-Dimethylnaphthalene
https://www.sigmaaldrich.com/catalog/product/aldrich/358932?lang=zh®ion=CN
http://www.titrations.info/EDTA-titration-aluminum
http://pubs.rsc.org/en/content/articlehtml/1971/an/an9719600591
http://pubs.rsc.org/en/content/articlehtml/1968/an/an9689300142
https://pubs.acs.org/doi/pdf/10.1021/ac60088a056
