乙酰丙酮的酮式-烯醇式互变异构的核磁共振研究——推荐一个物理化学实验

doi:10.3866/PKU.DXHX202304040

Abstract

Abstract:

A physical chemistry experiment involving organic chemistry, computational chemistry, and instrumental analysis is described for junior students majoring in chemistry. Keto-enol tautomerism is a fundamental concept in undergraduate organic chemistry. The keto-enol tautomeric equilibrium of acetylacetone in a series of binary solvent mixtures of deuterated chloroform and deuterated dimethyl sulfoxide with various polarities was explored using NMR spectroscopy and theoretical computations. The effect of solvent polarity on the equilibrium is discussed in combination with NMR and theoretical computation results. This experiment facilitates students' understanding of abstract concepts enables them to integrate theory with experiments and systematically analyze multiple techniques to explore chemical processes and principles.

Key words: NMR, Keto-enol tautomerism, Mixed solvent, Acetylacetone

Liubin Feng, Jie Ouyang, Dongli An, Jianliang Ye. NMR Study of Keto-Enol Tautomeric Equilibrium in Acetylacetone: An Experiment for Physical Chemistry Laboratory[J].University Chemistry, 2023, 38(11): 216-222.

Figures/Tables 6

References 18

1	邢其毅; 裴伟伟; 徐瑞秋; 裴坚. 基础有机化学(下册), 第4版北京: 北京大学出版社, 2016, 667
2	郝娇娇; 王长生. 化学学报, 2009, 67 (12), 1285. doi: 10.3321/j.issn:0567-7351.2009.12.002
3	尚善斋; 高莉; 何靓; 雷声; 李源栋; 蒋举兴. 云南大学学报(自然科学版), 2018, 40 (1), 139.
4	Lan H. ; Li Q. ; Li Y. ; Xiao S. ; Li Y. ; Yan X. ; Yuan S. ; Zhu P. Dyes Pigments 2018, 155, 121. doi: 10.1016/j.dyepig.2018.03.031
5	Wang X. ; Zhao W. ; Al-Abdul-Wahid S. ; Lu Y. ; Cheng T. ; Madsen J. J. ; Ye L. Bioconjug. Chem. 2021, 32, 99. doi: 10.1021/acs.bioconjchem.0c00670
6	Keeffe J. R. ; Kresge A. J. The Chemistry of Enols Chichester, UK: John Wiley & Sons, Inc., 1990, pp. 399- 480.
7	Datar A. ; Paithankar H. ; Deb P. ; Chugh J. ; Bagchi S. ; Mukherjee A. ; Hazra A. J. Phys. Chem. B 2022, 126, 5735. doi: 10.1021/acs.jpcb.2c02507
8	Jiang G. ; Tang Z. ; Han H. ; Ding J. ; Zhou P. J. Phys. Chem. B 2021, 125, 9296. doi: 10.1021/acs.jpcb.1c04776
9	Singh S. K. ; Vuppuluri V. ; Sun B.-J. ; Chang B.-Y. ; Eckhardt A. K. ; Son S. F. ; Chang A. H. H. ; Kaiser R. I. J. Phys. Chem. Lett. 2021, 12, 6062. doi: 10.1021/acs.jpclett.1c01610
10	Luo F. ; A R. ; Sun X. ; Gong Y. J. Chem. Educ. 2020, 97, 3829. doi: 10.1021/acs.jchemed.0c00039
11	Garland C. W. ; Nibler J. W. ; Shoemaker D. P. Experiments in Physical Chemistry 8th ed. New York, NY, USA: The McGraw-Hill, 2009, pp. 466- 474.
12	韩国彬; 夏文生. 物理化学实验, 第2版厦门: 厦门大学出版社, 2019.
13	北京大学化学学院物理化学实验教学组. 物理化学实验, 第4版北京: 北京大学出版社, 2002.
14	Cortney C. H. ; Krishnan V. V. J. Chem. Educ. 2020, 97, 825. doi: 10.1021/acs.jchemed.9b00737
15	Cook A. G. ; Feltman P. M. J. Chem. Educ. 2007, 84, 1827. doi: 10.1021/ed084p1827
16	Wiberg K. B. ; Ochterski J. ; Streitwieser A. J. Am. Chem. Soc. 1996, 118, 8291. doi: 10.1021/ja960631m
17	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.; et al. Gaussian 09, revision D. 01; Gaussian, Inc.: Wallingford, CT, USA, 2013.
18	董建伟; 李雪娇; 蔡乐; 缪应纯. 大学化学, 2019, 35 (3), 113.

DMSO-d₆体积分数(%)	ε
0	4.80
25	5.28
50	8.74
75	25.04
100	46.70

溶剂	H3/H3’		CH₃		烯醇占比/%	K_eq	T₁ ^a/s
DMSO-d₆含量/%	烯醇式	酮式	烯醇式	酮式	烯醇占比/%	K_eq	T₁ ^a/s
0	5.50	3.59	2.05	2.25	84.7	5.54	5.73
25	5.55	3.63	2.04	2.22	80.3	4.04	6.12
50	5.59	3.65	2.03	2.17	73.1	2.72	5.47
75	5.64	3.67	2.02	2.15	67.1	2.03	5.92
100	5.69	3.69	2.02	2.13	56.6	1.31	6.38

溶剂	烯醇式		酮式		烯醇式玻尔兹曼比例
DMSO-d₆含量/%	自由能/(a.u.)	偶极矩/D	自由能/(a.u.)	偶极矩/D	烯醇式玻尔兹曼比例
0	−345.73362	3.53	−345.73157	1.81	89.8
25	−345.73370	3.55	−345.73178	1.82	88.5
50	−345.73407	3.64	−345.73267	1.87	81.5
75	−345.73451	3.73	−345.73365	1.93	71.6
100	−345.73463	3.76	−345.73392	1.95	67.9

[1]	Chengshan Yuan, Xiaolong Li, Xiuping Yang, Xiangfeng Shao, Zitong Liu, Xiaolei Wang, Yongwen Shen. Standardized Operational Guidelines for Mixed-Solvent Recrystallization in Organic Chemistry Experiment [J]. University Chemistry, 2025, 40(5): 122-127.
[2]	Jing Wu, Wei Wang, Jingfeng Lan, E Yu, Qiaosheng Pu. New Life of an Old Spectrometer: An Innovative Experiment Based on the Digitization of an Obsolete Instrument [J]. University Chemistry, 2025, 40(2): 59-66.
[3]	Wenwen Zhang, Peichao Zhang, Conghao Gai, Xiaoyun Chai, Yan Zou, Qingjie Zhao. Unveiling Kinetics at Natural Abundance: ¹³C NMR Isotope Effect Experiments [J]. University Chemistry, 2025, 40(10): 203-207.
[4]	Zhuoming Liang, Ming Chen, Zhiwen Zheng, Kai Chen. Multidimensional Studies on Ketone-Enol Tautomerism of 1,3-Diketones By ¹H NMR [J]. University Chemistry, 2024, 39(7): 361-367.
[5]	Hong Lu, Yidie Zhai, Xingxing Cheng, Yujia Gao, Qing Wei, Hao Wei. Advancements and Expansions in the Proline-Catalyzed Asymmetric Aldol Reaction [J]. University Chemistry, 2024, 39(5): 154-162.
[6]	Liubin Feng, Yuteng Qu, Yuhang Jiang, Bifang Li, Jie Ouyang. Determination of Magnetic Susceptibility of Metal Coordination Complexes in Solution Using Nuclear Magnetic Resonance Spectroscopy: A Recommended Physical Chemistry Teaching Experiment [J]. University Chemistry, 2024, 39(12): 244-250.
[7]	Bangyan Chen, Xinyu Cheng, Ti Zhou, Lisen Sun, Yongmei Liu. Study on NMR Assisted Selective Oxidation of Fluorobenzyl Alcohol Catalyzed by Gold Nanoparticles [J]. University Chemistry, 2022, 37(7): 2111010-.
[8]	Menglong Zhao, Dailei Yuan, Zi Ye, Fang Fang, Yuena Yu. Electrooxidative Cross-Coupling with Hydrogen Evolution to Construct C—N Bonds: Design and Exploration of Electrochemical Technology in Organic Chemistry Laboratory Teaching [J]. University Chemistry, 2022, 37(5): 2109108-.
[9]	Yaofeng Yuan, Baoxu Wang, Liangsen Huang, Jiajia Cheng. Analysis of Isomerization Products by Proton Nuclear Magnetic Resonance Spectroscopy [J]. University Chemistry, 2022, 37(3): 2105010-.
[10]	Zhonghua Xi, Dadong Lu, Jie Dai, Tao Ye, Wenwei Zhang. Determination of Enantiomeric Purity of Binaphthol by NMR Method [J]. University Chemistry, 2022, 37(2): 2109027-.
[11]	Peng Zhang, Qian Zhang, Hua Zhong, Caifeng Ding. Optical Analysis for Reduced Glutathione Using o-Phthalaldehyde: Recommend an Instrumental Analysis Experiment [J]. University Chemistry, 2021, 36(9): 2012040-.
[12]	Keyin Ye, Xianggui Zhang, Yaofeng Yuan. Structural Analysis of Complex Organic Molecules by Two-Dimensional Nuclear Magnetic Resonance Spectroscopy [J]. University Chemistry, 2021, 36(9): 2106023-.
[13]	Fei Ding, Cui Zhang, Xiaohang Qiu. Exploration and Improvement of NMR Experiment Teaching under New Form [J]. University Chemistry, 2021, 36(7): 2012050-.
[14]	Wenxue Chen, Shasha Liu, Huixiang Li. Improvement of the Determination of Components in Paracetamol, Aminophenazone, Caffeine and Chlorpheniramine Maleate Tablet Using ¹H Nuclear Magnetic Resonance Spectroscopy [J]. University Chemistry, 2021, 36(2): 2002045-.
[15]	Anna Tang, Yancong Ren, Xiaojuan Deng, Guosheng Ding. The Development of Cleaning Methods for Liquid Nuclear Magnetic Resonance Tubes [J]. University Chemistry, 2021, 36(2): 2003034-.

NMR Study of Keto-Enol Tautomeric Equilibrium in Acetylacetone: An Experiment for Physical Chemistry Laboratory

RichHTML

PDF

Like

Knowledge

Abstract

Cite this article

share this article

Figures/Tables 6

References 18

Related Articles 15

Metrics

Recommended 0