Table 2 Optimization of dehydrogenative condensation of 1a and CH3OH.

From: Reversible interconversion between methanol-diamine and diamide for hydrogen storage based on manganese catalyzed (de)hydrogenation

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Entry

n

Base

b [mL]

2a [%]

2b [%]

3 [%]

H2 [%]d

1

6

tBuOK

0.4

86

9

5

92 (95.5%)

2

8

tBuOK

0.4

86

5

8

89 (94.8%)

3

4

tBuOK

0.4

80

13

7

85 (96.7%)

4

6

tBuONa

0.4

30

22

46

48 (>99.9%)

5

6

KOMe

0.4

85

10

5

90 (98.5%)

6

6

KOH

0.4

71

14

15

80 (99.8%)

7

6

tBuOK

0.2

77

8

15

82 (96.4%)

8

6

tBuOK

0.6

86

11

3

90 (93.5%)

9

6

tBuOK

1

77

17

5

88 (90.2%)

10a

6

tBuOK

0.4

76

14

7

84 (97.8%)

11b

6

tBuOK

0.4

97

<1

2

98 (98.7%)

12c

6

tBuOK

0.4

93

5

2

90 (>99.9%)

  1. Reaction conditions: 1 (0.25 mmol), VI (2 mol%), MeOH, tBuOK (4 mol%), and dioxane were reacted at 165 °C for 16 h. The conversion and yield were determined by NMR and GC, respectively
  2. aThe reaction temperature was 150 °C.
  3. bAfter 2 h, the reaction mixture was cooled to room temperature and the evolved gas was released from the system. The temperature was then increased to 165 °C and the reaction was performed for a further 6 h.
  4. cVI (1 mol%) and tBuOK (4 mol%) were used. After 2 h, the reaction mixture was cooled to room temperature and the evolved gas was released from the system. After addition of VI (1 mol%), the temperature was increased to 165 °C and the reaction was performed for a further 6 h.
  5. dThe yield of H2 was calculated on the basis of maximum H2 evolution with respect to 100% conversion of 1–2a (4 mmol H2 per mmol of 1). The H2 purity is shown in parentheses.
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