Microwave Assisted Solvent-Free Synthesis of Some Imine Derivatives

Table 3

Synthesis of imine derivatives under microwave irradiation.

N	Ar	R1	R2	R3	Microwave^a		Classical^b		m.p °C	Lit. m.p °C
					Yield %	𝑡/min	Yield %	𝑡/min
1a		OH	H	H	94	1.5	76	120	188–190	190 [22]
2a		OH	H	Cl	93	1.5	—	—	159–162	156–156.5 [23]
3a		OH	CH3	H	93	1.5	—	—	199–202	—
4a		H	H	H	97	1.0	73	120	50–53	50-51 [24]
5a		H	Cl	H	94	1.5	—	—	103–105	104 [12]
6a		H	CH3O	H	96	1.5	—	—	83–85	82–83.5 [25]
7a		H	CH3	H	97	1.5	—	—	93-94	90–91.5 [25]
1b		OH	H	H	95	1.5	63	120	116–118	117 [26]
2b		OH	H	Cl	92	2.0	—	—	123–125	—
3b		OH	CH3	H	91	2.0	—	—	134–137	—
4b		H	H	H	98	1.0	79	120	63–66	64-65 [24]
5b		H	Cl	H	94	1.5	—	—	110-111	110-111 [24]
6b		H	CH3O	H	91	3.0	—	—	124–126	124-125 [27]
7b		H	CH3	H	93	1.5	—	—	126–128	125 [27]
1c		OH	H	H	91	1.5	67	120	90-91	91–93 [22]
2c		OH	H	Cl	95	1.0	—	—	86–88	—
3c		OH	CH3	H	93	1.5	—	—	86-87	—
4c		H	H	H	97	1.0	73	120	58–60	63–63.5 [24]
5c		H	Cl	H	97	1.5	—	—	90–92	92 [16]
6c		H	CH3O	H	95	1.5	—	—	147–149	145-146 [24]
7c		H	CH3	H	91	1.5	—	—	92-93	91-92 [24]
1d		OH	H	H	95	1.5	67	120	89–91	92 [22]
2d		OH	H	Cl	91	1.5	—	—	91–93	—
3d		OH	CH3	H	94	1.5	—	—	97-98	—
4d		H	H	H	96	1.0	75	120	108–111	108-109 [12]
5d		H	Cl	H	96	1.5	—	—	105–107	105 [12]
6d		H	CH3O	H	97	1.5	—	—	120-121	119-120 [12]
7d		H	CH3	H	90	1.5	—	—	75–77	76-77 [28, 29]

aUnder solvent-free reaction using microwave.
^bProcedure: 1 mmol aldehyde (10 mL of ethanol) and 1 mmol amine (10 mL of ethanol) are mixed a balloon and then boiled under reflux on a hot plate.