GREY THEORY STUDY ON INHIBITION OF COMPOUNDS OFBENZENE NITRILES TO CARBON STEEL IN CHLORHYDRIC ACID

The relations between inhibition efficiency of carbon steel in hydrochloric acid and molecular structure of compounds of benzene nitriles were studied by constructing the grey inhibition model of inhibition system.Benzene nitriles studied included parent benzene nitriles(cinnamonitrile,benzonitrile,benzeneacetonitrile,isopropyl benzeneacetonitrile) and para-chloro benzene nitriles(para-chloro cinnamonitrile,para-chloro benzonitrile,para-chloro benzeneacetonitrile,para-chloroisopropyl benzeneacetonitrile).Results showed that the relations between inhibition efficiency of carbon steel in hydrochloric acid and molecular structure of compounds of benzene nitriles could be expressed by GM(0,3).The expressions of GM(0,3) were η (1) 1=0 4640 E (1) LUMO -3 2777σ (1) N+0 4683(for parent benzene nitriles) and η (1) Ⅱ=0 1256 E (1) LUMO -7 3096σ (1) N-0 0759(for para-chloro benzene nitriles).The expressions of GM(0,3) described the relations between inhibition efficiency of carbon steel in hydrochloric acid and molecular structure of compounds of benzene nitriles.Inhibition efficiency of compounds of benzene nitriles to carbon steel in hydrochloric acid mainly related to σ N and E LUMO ,and the more the σ N (absolute value) and the less the E LUMO ,the more the inhibition efficiency.