. 2017 Jun 12;15(6):171. doi: 10.3390/md15060171

Table 1.

Calculated and experimental chemical shifts for 1, 2, and deprotonated 2 (carboxylate), with deviations shown (largest deviations are shown in bold italics). ¹

Atom Label	Exp. δ	Anhydride (1) δ	Abs. Dev.	Acid (2) δ	Abs. Dev.	Carboxylate δ	Abs. Dev.
C6	170.7	168.7	2.0	171.4	0.7	172.2	1.5
C5	170.4	168.9	1.5	172.5	2.1	172.4	2.0
C7	161.0	156.6	4.4	159.1	1.9	158.4	2.6
C3	137.4	133.9	3.5	138.2	0.8	140.7	3.3
C8	136.2	139.8	3.6	139.4	3.2	138.2	2.0
C12	131.0	132.7	1.7	129.8	1.2	131.2	0.2
C4	124.7	123.5	1.2	124.6	0.1	123.3	1.4
C11	113.1	*103.5*	*9.6*	112.0	1.1	116.6	3.5
C10	108.6	*115.9*	*7.3*	108.1	0.5	107.6	1.0
C15	87.4	85.6	1.8	86.6	0.8	85.9	1.5
C2	60.4	*65.7*	*5.3*	59.0	1.4	61.6	1.2
C9	43.8	47.6	3.8	47.6	3.8	46.9	3.1
C16	26.1	24.8	1.3	24.4	1.7	26.0	0.1
C13	17.6	*22.6*	*5.0*	17.9	0.3	17.8	0.2
C1	17.2	16.0	1.2	16.1	1.1	16.7	0.5
C14	14.9	14.6	0.3	14.0	0.9	15.1	0.2
	MAD ²		3.3		1.3		1.5
	MAX ³		*9.6*		3.8		3.5
H27	6.95	7.11	0.16	7.24	0.29	7.18	0.23
H26	6.93	7.10	0.17	7.11	0.19	7.05	0.12
H29	4.21	4.17	0.04	4.38	0.17	4.23	0.02
H23	3.51	3.58	0.07	*4.05*	*0.54*	3.66	0.15
H17-19	2.28	2.54	0.16	2.64	0.26	2.49	0.11
H28,31,33	1.36	1.31	0.05	1.38	0.02	1.47	0.11
H25,30,32	1.28	1.31	0.03	1.31	0.03	1.29	0.01
H20-22	1.28	1.37	0.09	1.40	0.12	1.42	0.14
	MAD ²		0.10		0.20		0.11
	MAX ³		0.17		*0.54*		0.23

¹ Protons not seen in the experimental NMRs are not included here (OH’s and acid H). ² Mean absolute deviation. ³ Maximum absolute deviation. Deviations of <5 ppm (¹³C) and <0.3 ppm (¹H) are generally considered acceptable [6,7,8,9,10].