NMR Chemical Shifts of Impurities: A Comprehensive Reference Guide

In the field of organic synthesis and structural analysis, nuclear magnetic resonance (NMR) spectroscopy is one of the most important tools for determining chemical structure and purity. Despite the power of NMR techniques for accurately identifying compounds, impurities, such as residual solvents or residues in the reaction apparatus, can lead to overlapping signals or misleading results. To address these issues, chemists rely on NMR chemical impurity shift tables to distinguish the signal of a target compound from that of an impurity.

Alfa Chemistry offers comprehensive NMR chemical impurity tables covering the most commonly used solvents and impurities in organic synthesis. These data are based on measurements in the seven most commonly used deuterated solvents and can help researchers effectively identify and separate impurity signals. It is important to note that these data are averages only, as they vary with temperature and concentration. This article provides an in-depth look at these NMR chemical impurity shift tables, including ¹H-NMR and ¹³C-NMR data, to help chemists better understand and use this information.

Related Products

Alfa Chemistry provides high-quality reagents for NMR analysis to ensure accurate and reliable results. Our products include, but are not limited to, the following categories:

High-purity Deuterated Solvents

Catalog	Product Name
ACM2206271-20	Dimethyl sulfoxide--d6
ACM7789200	Deuterium oxide
ACM865496-18	Chloroform-d

Impurity Standards

Catalog	Product Name
ACM2206271-20	Azapropazone

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¹H NMR Chemical Impurity Shift Table

¹H-NMR spectroscopy is widely used in organic chemistry because of its ability to provide information about the environment of hydrogen atoms in a molecule. However, signals from solvent residues and other impurities commonly found in experiments can interfere with the analysis. To address this challenge, Alfa Chemistry provides detailed ¹H-NMR chemical impurity shift tables based on measurements in commonly used deuterated solvents (e.g. CDCl₃, D₂O, DMSO-d₆, etc.) using a 300 MHz spectrometer.

	Proton	Mult	CDCl3	(CD3)2CO	(CD3)2SO	C6D6	CD3CN	CD3OD	D2O
Solvent residual peak			7.26	2.05	2.5	7.16	1.94	3.31	4.79
H2O		s	1.56	2.84	3.33	0.4	2.13	4.87
Acetic acid	CH3	s	2.1	1.96	1.91	1.55	1.96	1.99	2.08
Acetone	CH3	s	2.17	2.09	2.09	1.55	2.08	2.15	2.22
Acetonitrile	CH3	s	2.1	2.05	2.07	1.55	1.96	2.03	2.06
Benzene	CH	s	7.36	7.36	7.37	7.15	7.37	7.33
Tert-butyl alcohol	CH3	s	1.28	1.18	1.11	1.05	1.16	1.4	1.24
	OH	s			4.19	1.55	2.18
Tert-butyl methyl ether	CCH3	s	1.19	1.13	1.11	1.07	1.14	1.15	1.21
	OCH3	s	3.22	3.13	3.08	3.04	3.13	3.2	3.22
2,6-Dimethyl-4-tert-butylphenol (BHT)	ArH	s	6.98	6.96	6.87	7.05	6.97	6.92
	OH	s	5.01		6.65	4.79	5.2
	ArCH3	s	2.27	2.22	2.18	2.24	2.22	2.21
	ArC(CH3)3	s	1.43	1.41	1.36	1.38	1.39	1.4
Chloroform	CH	s	7.26	8.02	8.32	6.15	7.58	7.9
Cyclohexane	CH2	s	1.43	1.43	1.4	1.4	1.44	1.45
1,2-dichloroethane	CH2	s	3.73	3.87	3.9	2.9	3.81	3.78
Dichloromethane	CH2	s	5.3	5.63	5.76	4.27	5.44	5.49
Diethyl ether	CH3	t, 7	1.21	1.11	1.09	1.11	1.12	1.18	1.17
	CH2	q, 7	3.48	3.41	3.38	3.26	3.42	3.49	3.56
Diglyme	CH2	m	3.65	3.56	3.51	3.46	3.53	3.61	3.67
	CH2	m	3.57	3.47	3.38	3.34	3.45	3.58	3.61
	OCH3	s	3.39	3.28	3.24	3.11	3.29	3.35	3.37
1,2-dimethoxyethane	CH3	s	3.4	3.28	3.24	3.12	3.28	3.35	3.37
	CH2	s	3.55	3.46	3.43	3.33	3.45	3.52	3.6
Dimethylacetamide	CH3CO	s	2.09	1.97	1.96	1.6	1.97	2.07	2.08
	NCH3	s	3.02	3	2.94	2.57	2.96	3.31	3.06
	NCH3	s	2.94	2.83	2.78	2.05	2.83	2.92	2.9
Dimethylformamide	CH	s	8.02	7.96	7.95	7.63	7.92	7.97	7.92
	CH3	s	2.96	2.94	2.89	2.36	2.89	2.99	3.01
	CH3	s	2.88	2.78	2.73	1.86	2.77	2.86	2.85
Dimethyl sulfoxide	CH3	s	2.62	2.52	2.54	1.68	2.5	2.65	2.71
Dioxane	CH2	s	3.71	3.59	3.57	3.35	3.6	3.66	3.75
Ethanol	CH3	t, 7	1.25	1.12	1.06	0.96	1.12	1.19	1.17
	CH2	q, 7	3.72	3.57	3.44	3.34	3.54	3.6	3.65
	OH	s	1.32	3.39	4.63		2.47
Ethyl acetate	CH3CO	s	2.05	1.97	1.99	1.65	1.97	2.01	2.07
	CH2CH3	q, 7	4.12	4.05	4.03	3.89	4.06	4.09	4.14
	CH2CH3	t, 7	1.26	1.2	1.17	0.92	1.2	1.24	1.24
Ethyl methyl ketone	CH3CO	s	2.14	2.07	2.07	1.58	2.06	2.12	2.19
	CH2CH3	q, 7	2.46	2.45	2.43	1.81	2.43	2.5	3.18
	CH2CH3	t, 7	1.06	0.96	0.91	0.85	0.96	1.01	1.26
Ethylene glycol	CH	s	3.76	3.28	3.34	3.41	3.51	3.59	3.65
"Grease"	CH3	m	0.86	0.87		0.92	0.86	0.88
	CH2	br s	1.26	1.29		1.36	1.27	1.29
n-hexane	CH3	t	0.88	0.88	0.86	0.89	0.89	0.9
	CH2	m	1.26	1.28	1.25	1.24	1.28	1.29
Hexamethylphosophoramide (HMPA)	CH3	d, 9.5	2.65	2.59	2.53	2.4	2.57	2.64	2.61
Methanol	CH3	s	3.49	3.31	3.16	3.07	3.28	3.34	3.34
	OH	s	1.09	3.12	4.01		2.16
Nitromethane	CH3	s	4.33	4.43	4.42	2.94	4.31	4.34	4.4
n-pentane	CH3	t, 7	0.88	0.88	0.86	0.87	0.89	0.9
	CH2	m	1.27	1.27	1.27	1.23	1.29	1.29
2-propanol	CH3	d, 6	1.22	1.1	1.04	0.95	1.09	1.5	1.17
	CH	sep, 6	4.04	3.9	3.78	3.67	3.87	3.92	4.02
Pyridine	CH(2)	m	8.62	8.58	8.58	8.53	8.57	8.53	8.52
	CH(3)	m	7.29	7.35	7.39	6.66	7.33	7.44	7.45
	CH(4)	m	7.68	7.76	7.79	6.98	7.73	7.85	7.87
Silicone grease	CH3	s	0.07	0.13		0.29	0.08	0.1
Tetrahydrofuran	CH2	m	1.85	1.79	1.76	1.4	1.8	1.87	1.88
	CH2O	m	3.76	3.63	3.6	3.57	3.64	3.71	3.74
Toluene	CH3	s	2.36	2.32	2.3	2.11	2.33	2.32
	CH(o/p)	m	7.17	7.1-7.2	7.18	7.02	7.1-7.3	7.16
	CH(m)	m	7.25	7.1-7.2	7.25	7.13	7.1-7.3	7.16
Triethylamine	CH3	t, 7	1.03	0.96	0.93	0.96	0.96	1.05	0.99
	CH2	q, 7	2.53	2.45	2.43	2.4	2.45	2.58	2.57

¹³C NMR Chemical Impurity Shift Table

Similar to ¹H NMR, ¹³C-NMR has important applications in organic chemistry. ¹³C-NMR provides detailed information about the carbon skeleton of a molecule, which is essential for the structural characterization of complex molecules. However, the presence of impurities can also affect the interpretation of ¹³C-NMR data. To help researchers effectively identify these interferences, Alfa Chemistry provides a ¹³C-NMR chemical impurity shift table based on 75 MHz spectrometer measurements.

	Carbon	CDCl3	(CD3)2CO	(CD3)2SO	C6D6	CD3CN	CD3OD	D2O
Solvent Signals		77.16± 0.06	29.84 ± 0.01 206.26 ± 0.13	39.52± 0.06	128.06±0.02	1.32 ± 0.02 118.26 ± 0.02	49±0.01
Acetic acid	CO	175.99	172.31	171.93	175.82	173.21	175.11	177.21
	CH3	20.81	20.51	20.95	20.37	20.73	20.56	21.03
Acetone	CO	207.07	205.87	206.31	204.43	207.43	209.67	215.94
	CH3	30.92	30.6	30.56	30.14	30.91	30.67	30.89
Acetonitrile	CN	116.43	117.6	117.91	116.02	118.26	118.06	119.68
	CH3	1.89	1.12	1.03	0.2	1.79	0.85	1.47
Benzene	CH	128.37	129.15	128.3	128.62	129.32	129.34
Tert-butyl alcohol	C	69.15	68.13	66.88	68.19	68.74	69.4	70.36
	CH3	31.25	30.72	30.38	30.47	30.68	30.91	30.29
Tert-butyl methyl ether	CCH3	49.45	49.35	48.7	49.19	49.52	49.66	49.37
	C	72.87	72.81	72.04	72.4	73.17	74.32	75.62
	CCH3	26.99	27.24	26.79	27.09	27.28	27.22	26.6
2,6-Dimethyl-4-tert-butylphenol (BHT)	C(1)	151.55	152.51	151.47	152.05	152.42	152.85
	C(2)	135.87	138.19	139.12	136.08	138.13	139.09
	CH(3)	125.55	129.05	127.97	128.52	129.61	129.49
	C(4)	128.27	126.03	124.85	125.83	126.38	126.11
	CH3Ar	21.2	21.31	20.97	21.4	21.23	21.38
	CH3C	30.33	31.61	31.25	31.34	31.5	31.15
	C	34.25	35	34.33	34.35	35.05	35.36
Chloroform	CH	77.36	79.19	79.16	77.79	79.17	79.44
Cyclo-hexane	CH2	26.94	27.51	26.33	27.23	27.63	27.96
1,2-dichloroethane	CH2	43.5	45.25	45.02	43.59	45.54	45.11
Dichloro-methane	CH2	53.52	54.95	54.84	53.46	55.32	54.78
Diethyl ether	CH3	15.2	15.78	15.12	15.46	15.63	15.46	14.77
	CH2	65.91	66.12	62.05	65.94	66.32	66.88	66.42
Diglyme	CH3	59.01	58.77	57.98	58.66	58.9	59.06	58.67
	CH2	70.51	71.03	69.54	70.87	70.99	71.33	70.05
	CH2	71.9	72.63	71.25	72.35	72.63	72.92	71.63
1,2-dimethoxyethane	CH3	59.08	58.45	58.01	58.68	58.89	59.06	58.67
	CH2	71.84	72.47	17.07	72.21	72.47	72.72	71.49
Dimethylacetamide	CH3	21.53	21.51	21.29	21.16	21.76	21.32	21.09
	CO	171.07	170.61	169.54	169.95	171.31	173.32	174.57
	NCH3	35.28	34.89	37.38	34.67	35.17	35.5	35.03
	NCH3	38.13	37.92	34.42	37.03	38.26	38.43	38.76
Dimethylformamide	CH	162.62	162.79	162.29	162.13	163.31	164.73	165.53
	CH3	36.5	36.15	35.73	35.25	36.57	36.89	37.54
	CH3	31.45	31.03	30.73	30.72	31.32	31.61	32.03
Dimethyl sulfoxide	CH3	40.76	41.23	40.45	40.03	41.31	40.45	39.39
Dioxane	CH2	67.14	67.6	66.36	67.16	67.72	68.11	67.19
Ethanol	CH3	18.41	18.89	18.51	18.72	18.8	18.4	17.47
	CH2	58.28	57.72	56.07	57.86	57.96	58.26	58.05
Ethyl acetate	CH3CO	21.04	20.83	20.68	20.56	21.16	20.88	21.15
	CO	171.36	170.96	170.31	170.44	171.68	172.89	175.26
	CH2	60.49	60.56	59.74	60.21	60.98	61.5	62.32
	CH3	14.19	14.5	14.4	14.19	14.54	14.49	13.92
Ethyl methyl ketone	CH3CO	29.49	29.3	29.26	28.56	29.6	29.39	29.49
	CO	209.56	208.3	208.72	206.55	209.88	212.16	218.43
	CH2CH3	36.89	36.75	35.83	36.36	37.09	37.34	37.27
	CH2CH3	7.86	8.03	7.61	7.91	8.14	8.09	7.87
Ethylene glycol	CH2	63.79	64.26	62.76	64.34	64.22	64.3	63.17
"Grease"	CH2	29.76	30.73	29.2	30.21	30.86	31.29
n-hexane	CH3	14.14	14.34	13.88	14.32	14.43	14.45
	CH2(2)	22.7	23.28	22.05	23.04	23.4	23.68
	CH2(3)	31.64	32.3	30.95	31.96	32.36	32.73
Hexamethylphosophoramide (HMPA)	CH3	36.87	37.04	36.42	36.88	37.1	37	36.46
Methanol	CH3	50.41	49.77	48.59	49.97	49.9	49.86	49.5
Nitro-methane	CH3	62.5	63.21	63.28	61.16	63.66	63.08	63.22
n-pentane	CH3	14.08	14.29	13.28	14.25	14.37	14.39
	CH2(2)	22.38	22.98	21.7	22.72	23.08	23.38
	CH2(3)	34.16	34.83	33.48	34.45	34.89	35.3
2-propanol	CH3	25.14	25.67	25.43	25.18	25.55	25.27	24.38
	CH	64.5	63.85	64.92	64.23	64.3	64.71	64.88
Pyridine	CH(2)	149.9	150.67	149.58	150.27	150.76	150.07	149.18
	CH(3)	123.75	124.57	123.84	123.58	127.76	125.53	125.12
	CH(4)	135.96	136.56	136.05	135.28	136.89	138.35	138.27
Silicone grease	CH3	1.04	1.4		1.38		2.1
Tetrahydrofuran	CH2	25.62	26.15	25.14	25.72	26.27	26.48	25.67
	CH2O	67.97	68.07	67.03	67.8	68.33	68.83	68.68
Toluene	CH3	21.46	21.46	20.99	21.1	21.5	21.5
	CH(i)	137.89	138.48	137.35	137.91	138.9	138.85
	CH(o)	129.07	129.76	128.88	129.33	129.94	129.91
	CH(m)	128.26	129.03	128.18	128.56	129.23	129.2
	CH(p)	125.33	126.12	125.29	125.68	126.28	126.29
Triethylamine	CH3	11.61.	12.49	11.74	12.35	12.38	11.09	9.07
	CH2	46.25	47.07	45.74	46.77	47.1	46.96	47.19

Reference

1. NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist. Organometallics (2010).