Research On Synthesis And Corrosion Inhibition Performance Of The Novel Dioxolane Imidazoline And Benzimidazole Derivatives

At present,the main way of resource utilization of waste oil is to prepare mixed fatty acids from waste oil by hydrolysis reaction,and then process it into plasticizer,flotation agent and surfactant,etc.However,during the reaction,the large amount of by-product glycerol produced is not fully utilized.Therefore,it is of practical significance of environmental protection to study the use of biomass glycerol as a raw material to prepare high value-added fine chemical products while creating economic benefits.In this paper,2-phenyl-4-hydroxymethyl-1.3-dioxolane(glycerol benzaldehyde)and 2-(p-methylphenyl)-4-hydroxymethyl-1.3-dioxolane(glycerol p-methyl benzaldehyde)were synthesized from glycerol,a byproduct of hydrolysis reaction of waste oil,by aldol condensation reaction with benzaldehyde or p-methylbenzaldehyde,and then 2-phenyl-4-carboxyl-1,3-dioxolane and 2-(p-methylphenyl)-4-carboxyl-1.3-dioxolane were synthesized with TEMPO as catalyst and sodium hypochlorite as oxidant.Finally,the intermediates were used to amide-cyclize with diethylenetramine,o-phenylenediamine and N-methyl-o-aniline hydrochloride respectively to synthesize six new imidazoline and benzimidazole corrosion inhibitors,it is include 2-phenyl-4-(1-N'-aminethyl-2'-imidazolinyl)-1.3-dioxolane(DBCI),2-phenyl-4-(2'-benzimidazolyl)-1,3-dioxolane(OBCI),2-phenyl-4-(1'-N-methyl-2'-benz-imidazolyl)-1,3-dioxolane(MBCI),2-(p-methylphenyl)-4-(1-N'-aminethyl-2'-imidazolinyl)-1.3-dioxolane(DPCI),2-(p-methylphenyl)-4-(2'-benzimidazolyl)-1,3-dioxolane(OPCI)and 2-(p-methylphenyl)-4-(1'-N-methyl-2'-benzimidazolyl)-1,3-dioxolane(MPCI).The synthesis conditions of 2-aryl-4-carboxyl acid-1,3-dioxolane and the six novel corrosion inhibitors were optimized by orthogonal design experiments.The products were characterized by IR,UV,MS and NMR spectrum.The experimental results show that the six corrosion inhibitors have been successfully prepared.The weight loss method corrosion test showed that the six corrosion inhibitors had excellent corrosion inhibition effect for Q235 carbon steel in 5% HCl at 60 °C for 6 h.In the optimal dosage(DBCI: 60 mg/L;OBCI: 100 mg/L;MBCI: 100 mg/L;DPCI: 60 mg/L;OPCI: 80 mg/L;MPCI: 120 mg/L),corrosion inhibition rate of six corrosion inhibitors for Q235 carbon steel under experimental conditions can reached 99.16%,98.70%,98.47%,98.57%,97.74%,and 97.24%.The comparison test results show that the corrosion inhibition performance of the six corrosion inhibitors is comparable to the commercial imidazoline corrosion inhibitor.The results of electrochemical tests show that the corrosion current density of Q235 steel decreases with the increase of inhibitor concentration,and the six inhibitors are all mixed-type corrosion inhibitor for restraining cathodic process.The Nyquist diagram shows a single time constant diffusion capacitive reactance arc and the solution resistance and polarization resistance increase significantly after adding six inhibitors.With the increase of inhibitor concentration,the larger the radius of AC capacitance arc resistance,the better the corrosion inhibition effect.The electrochemical corrosion inhibition rates of the six inhibitors are basically the same as those measured by static weightlessness method.The results show that the adsorption behavior of corrosion inhibitors on Q235 steel surface conforms to Langmuir adsorption isotherm and the free energy of Gibbs adsorption ranges from-52.65 to-46.76 kJ/mol.It shows that the adsorption process is chemical adsorption,and the adsorption process is spontaneous.The results of SEM showed that all six corrosion inhibitors can form compact adsorption film on Q235 carbon steel surface.This can prove that all the six products are adsorption model corrosion inhibitor.