Investigation on Redox Mechanism of p-Nitrophenol in Aprotic Media†

doi:10.7503/cjcu20170107

Abstract

Abstract:

The mechanism of electrochemical reduction of p-nitrophenol in acetonitrile was explored by means of in situ FTIR spectroelectrochemistry, cyclic voltabsorptometry(CVA) and derivative cyclic voltabsorptometry(DCVA). Also, the possible structures of free radical anions and dimers in the reaction were calculated by the B3LYP method at the 6-311++G^* level. Electrochemical experimental results showed that CV curve changed with the change of p-nitrophenol concentration. When increasing the number of CV scan turns, the entire electrochemical process was chemically reversible by observing 3D IR spectra. Both CV and rapid-scan IR spectra(CVA and DCVA) supported that for p-nitrophenol in acetonitrile solvent, complex self-protonation reaction occured during electrochemical reduction. The self-protonation reaction took place after PNP was reduced to free radical anion; when the PNP concentration was high, the dimerization reaction happened from the free radical anion and products of self-protonation reaction, followed by the p-nitrophenol anion being reduced to the corresponding radical dianion. At the same time, when the concentration of p-nitrophenol was decreased, the electrochemical process would also change, that is, the dimerization phenomenon disappeared, and the anion free radical would continue to reduce.

Key words: In situ FTIR spectroelectrochemistry, Cyclic voltabsorptometry(CVA), Derivative cyclic voltabsorptometry(DCVA), p-Nitrophenol, Self-protonation reaction

CLC Number:

O646
O657.1

TrendMD:

LI Yuying, LI Dan, CHENG Longjiu, JIN Baokang. Investigation on Redox Mechanism of p-Nitrophenol in Aprotic Media^†[J]. Chem. J. Chinese Universities, 2017, 38(11): 2023.

Figures/Tables 9

Fig.1 Cyclic voltammogram(A), the corresponding 3D IR spectrum(B), CVAs(C) and selected DCVAs(D) in acetonitrile containing 10 mmol/L PNP and 0.2 mol/L Bu4NClO4 as the supporting electrolyteTo make the DCVA data readily comparable to CV, the partial data in DCVA were multiplied by -1. Au electrode as working electrode, Ag/AgCl as reference electrode. The potential scan rate was 10 mV/s.

Table 1 Attribution of IR absorption peaks of PNP in acetonitrile

$ν ˙$ /cm^-1	Assignment	$ν ˙$ /cm^-1	Assignment
1110	Cl $O 4 -$ from TBAP	1318	ν_N—O from ^-OC₆H₄NOOH^·
1156	ν_C—N from ^-OC₆H₄NOOH^·-	1341	$ν NO$ from PNP
1164	ν_C—N from HOC₆H₄NOOH^·	1472^[9]	ν_N—O from ^-OC₆H₄NOOH^·
1195	ν_C—N from ^-OC₆H₄NOOH^·	1533	ν_N—O from HOC₆H₄NOOH^·
1272^[29]	ν_C—O from ^-OC₆H₄NOOH^·-	1564	Benzene skeleton vibration from ^-OC₆H₄NOOH^·
1279	ν_C—O from HOC₆H₄NOOH^·	1587	Benzene skeleton vibration from HOC₆H4NOOH^·

Table 1 Attribution of IR absorption peaks of PNP in acetonitrile

$ν ˙$ /cm^-1	Assignment	$ν ˙$ /cm^-1	Assignment
1110	Cl $O 4 -$ from TBAP	1318	ν_N—O from ^-OC₆H₄NOOH^·
1156	ν_C—N from ^-OC₆H₄NOOH^·-	1341	$ν NO$ from PNP
1164	ν_C—N from HOC₆H₄NOOH^·	1472^[9]	ν_N—O from ^-OC₆H₄NOOH^·
1195	ν_C—N from ^-OC₆H₄NOOH^·	1533	ν_N—O from HOC₆H₄NOOH^·
1272^[29]	ν_C—O from ^-OC₆H₄NOOH^·-	1564	Benzene skeleton vibration from ^-OC₆H₄NOOH^·
1279	ν_C—O from HOC₆H₄NOOH^·	1587	Benzene skeleton vibration from HOC₆H4NOOH^·

Fig.2 CVAs(A) and selected DCVAs(B) in acetonitrile containing 15 mmol/L PNP

Fig.3 Consecutive CV(A) and the corresponding 3D IR spectra(B) in acetonitrile containing 10 mmol/L PNP The experimental conditions were the same as those of Fig.1.

Fig.4 CV(A), the corresponding 3D IR spectra(B), CVAs(C) and selected DCVAs(D) in acetonitrile containing 10 mmol/L PNPThe scan range was -0.3—-1.5—1.0 V. Experimental conditions were the same as those of Fig.1.

Fig.5 Optimization of dimer structures at the B3LYP/6-311++G** level of calculation

Fig.6 CV curves of PNP and +Na-OC6H4NO2 for comparisonAu electrode as working electrode, Ag/AgCl as reference electrode. The potential scan rate was 10 mV/s.

Fig.7 CV curves in acetonitrile containing different concentrations of PNPExperimental conditions were the same as those of Fig.1.

Fig.8 CV curve(A), 3D IR spectra(B), CVAs(C) and selected DCVAs(D) in acetonitrile containing 5 mmol/L PNPThe partial data in DCVA(D) were multiplied by -1 or divided by 2. Experimental conditions were the same as those of Fig.1.

References 33

[1]	Nasima A., Kausar J. N., Safeer A., Yaseen K. A., Skibsted L. H., Chem. J. Chinese Universities,2010, 31(26), 6184-6189
[2]	Álvarez-Lueje A., Pessoa H., Núñnez-Vergara L. J., Squella J. A., Bioelectrochem. Bioenerg., 1998, 46(1), 21-28
[3]	Baeza A., Ortiz J. L.,González I., J. Electroanal. Chem., 1997, 429(1), 121-127
[4]	Zhang H. L., Zheng L. X., Xu L., Nong J. Y., J. Wuhan Univ. Sci. Tech.(Nat. Sci. Ed.), 2007, 30(6), 632-635
	(张惠灵, 郑利祥, 徐亮, 农佳莹. 武汉科技大学学报(自然科学版), 2007, 30(6), 632-635)
[5]	Peng X. L., Chen C., Long J., Sun J., Chem. J. Chinese Universities,2010, 31(5), 164-167
	(彭晓兰, 陈晨, 龙娟, 孙婧. 给水排水, 2007, 33(5), 164-167)
[6]	Yuan S. H., Tian M., Lu X. H.,J. Hazard. Mater., 2006, 137(2), 573-580
[7]	Honeychurch C. K., Hart J. P., Electroanalysis,2007, 19(21), 2176-2184
[8]	Wan N. S., Gu J. D., Huang J. H., Gao C. D., Environmental Science., 2007, 28(2), 422-426
	(万年升, 顾继东, 黄锦辉, 高传德. 环境科学, 2007, 28(2), 422-426)
[9]	Tian D. X., Jin B. K., Chem. J. Chinese Universities,2010, 31(25), 9144-9151
[10]	Xie Y. L., Li D., Jin B. K., J. Electroanal. Chem., 2016, 774, 1-6
[11]	Rappich J., Hinrichs K., Electrochem. Commun., 2009, 11(12), 2316-2319
[12]	Li Y. P., Cao H. B., Liu C. M., Zhang Y., J. Hazard. Mater., 2007, 148(1/2), 158-163
[13]	Zhang Y. X., Mao X. B., Ren S. Y., Ma C. A., Chem. J. Chinese Universities,2010, 31(2), 293-296
[14]	Andres T., Eckmann L., Smith D. K., Chem. J. Chinese Universities,2010, 31, 257-268
[15]	Prasad M. A., Sangaranarayanan M. V., Chem. J. Chinese Universities,2010, 31(2), 242-246
[16]	Wang A. J., Cheng H. Y., Liang B., Ren N. Q., Cui D., Lin N., Kim B. H., Rabaey K., Environ. Sci. Technol., 2011, 45(23), 10186-10193
[17]	Gard J. C., Lessard J., Mugnier Y., Chem. J. Chinese Universities,2010, 31(5), 677-680
[18]	Cyr A., Huot P., Marcoux J. F., Belot G., Laviron E., Lessard J., Chem. J. Chinese Universities,2010, 31(3), 439-445
[19]	Wang W., Wang K., He J. J., Zhang X. T., Wang C., Zhao Z. W., Cui F. Y., Chem. J. Chinese Universities,2010, 31(6), 1012-1017
[20]	Wang H., Ye X. H., Chen L. M., Lu J. X., He M. Y., Chem. J. Chinese Universities,2010, 31(2), 326-329
	(王欢, 叶小鹤, 陈黎明, 陆嘉星, 何鸣元. 高等学校化学学报, 2005, 26(2), 326-329)
[21]	Amatore C., Copobianco G., Farnia G., Sandona G., Saveant J. M., Severin M. G., Vianello., J. Am. Chem. Soc., 1985, 107(7), 1815-1824
[22]	Forryan C. L., Lawrence N. S., Rees N. V., Compton R. G., J. Electroanal. Chem., 2004, 561(1/2), 53-65
[23]	Debbie S. S., Andrew J. W., Aldous L., Hardacre C., Richard G. C.,J. Electroanal. Chem., 2006, 596(2), 131-140
[24]	Li M. C., Wu H. F., Hu J. Q., Ma C. A., Acta Phys. Chim. Sin., 2008, 24(10), 1937-1940
	(李美超, 吴海峰, 胡佳琦, 马淳安. 物理化学学报, 2008, 24(10), 1937-1940)
[25]	Jin B. K., Huang J. L., Li L., Zhang S. Y., Tian Y. P., Yang J. Y., Anal. Chem., 2009, 81(11), 4476-4481
[26]	Astuti Y., Topoglidis E., Briscoe P. B., Fantuzzi A., Gilardi G., Durrant J. R., J. Am. Chem. Soc., 2004, 126(25), 8001-8009
[27]	Nekrasov A. A., Ivanov V. F., Gribkova O. L., Vannikov A. V., Chem. J. Chinese Universities,2010, 31(7), 1605-1613
[28]	Li D., Jin B. K., Chem. J. Chinese Universities,2010, 31(8), 1959-1964
	(李丹, 金葆康. 高等学校化学学报, 2013, 34(8), 1959-1964)
[29]	Wang J., Jin B., Cheng L., Chem. J. Chinese Universities,2010, 31, 152-157
[30]	Cheng W. X., Jin B. K., Huang P., Cheng L. J., Zhang S. Y., Tian Y. P., Chem. J. Chinese Universities,2010, 31(8), 3940-3948
[31]	House H. O., Feng E., Peet N. P., J. Org. Chem., 1971, 36(16), 2371-2375
[32]	Fu D.Q., Jin B. K.,Chin. J. Inorg. Chem., 2010, 26(11), 2001-2005
	(傅东祺, 金葆康. 无机化学学报, 2010, 26(11), 2001-2005)
[33]	Frisch M.J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Scalmani G., Barone V., Mennucci B., Petersson G. A., Nakatsuji H., Caricato M., Li X., Hratchian H. P., Izmaylov A. F., Bloino J., Zheng G., Sonnenberg J. L., Hada M., Ehara M., Toyota K., Fukuda R., Hasegawa J., Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., Vreven T. J., Montgomery J. A., Peralta J. E., Ogliaro F., Bearpark M., Heyd J. J., Brothers E., Kudin K. N., Staroverov V. N., Kobayashi R., Normand J., Raghavachari K., Rendell A., Burant J. C., Iyengar S. S., Tomasi J., Cossi M., Rega N., Millam J. M., Klene M., Knox J. E., Cross J. B., Bakken V., Adamo C., Gaussian 09, Revision B. 01, Gaussian, Inc., Wallingford CT, 2009