Methyl esterification of carboxylic acids with dimethyl carbonate promoted by K₂CO₃/tetrabutylammonium chloride

Figures & data

Table 1. Esterification of benzoic acid with DMC under catalysis of K₂CO₃/TBACl.

				Products (%, GC)
Entry	1a:DMC:K2CO3:TBACl^a	Temperature. (^oC)^b	Time (h)	2a	3a	Transformation (%)	Yield of 2a (%)
1	1:2:1:0	150	12	–	–	No reaction	–
2	1:2:1:0.1	150	12	99	1	23	22
3	1:2:1:0.2	150	12	97	3	57	55
4	1:2:1:0.3	150	12	94	6	64	61
5	1:2:1:0.5	150	12	61	39	79	53
6	1:2:1:1	150	12	44	56	82	42
7	1:2:0:0.3	150	12	96	4	24	23
8	1:2:0.1:0.3	150	12	98	2	83	82
9	1:2:0.2:0.3	150	12	98	2	77	76
10	1:2:0.5:0.3	150	12	97	3	67	65
11	1:2:0.7:0.3	150	12	96	4	61	59
12	1:1:0.1:0.3	150	12	75	25	35	28
13	1:3:0.1:0.3	150	12	100	0	77	77
14	1:4:0.1:0.3	150	12	84	16	80	70
15	1:5:0.1:0.3	150	12	84	16	16	14
16	1:2:0.1:0.3	150	9	99	1	44	43
17	1:2:0.1:0.3	150	15	98	2	83	82
18	1:2:0.1:0.3	150	18	98	2	84	83
19	1:2:0.1:0.3	150	24	99	1	82	81
20	1:2:0.1:0.3	130	12	99	1	4	4
21	1:2:0.1:0.3	170	12	97	3	88	86
22	1:2:0.1:0.3	190	12	97	3	89	87
^aMolar ratio.
^bThe temperature in the oil-bath.

Table 2. Esterification of some carboxylic acids with DMC under catalysis of K₂CO₃/TBACl.

		Products (%, GC)
Entry	Substrate	Methyl ester^a	Butyl ester	Transformation (%)	Yield of methyl ester (%)	References^b
23		98	2	92	90	38
24		94	6	95	90	39
25		98	2	90	89	40
26		96	4	94	90	40
27		97	3	74	72	41
28		94	6	79	75	41
29		98	2	90	88	41
30		96	4	89	86	38
31		98	2	75	74	38
32		98	2	85	84	42
33		98	2	8	8	41
^aThe purity and authenticity of methylated products were checked by GC–MS and ^1H NMR spectroscopy.
^bThe ^1H NMR spectral data of methyl esters are consistent with those reported in Section References.

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