Yield:33089-61-1 87.34%

Reaction Conditions:

with 2,4-xylidine hydrochloride;orthoformic acid triethyl ester;zinc(II) chloride at 95 - 180;

Steps:

1 Embodiment 1 preparation of double-carboxamidine

The reaction bottle adding 2, 4 - dimethyl aniline (121 g, 1 μM), N - methyl formamide (214 g, 1.45 μM), the original carboxylic acid triethyl ester (44.2 g, 0 . 75 μM), zinc chloride catalyst (1.36 g, 0.1 μM), 2, 4 - dimethyl aniline hydrochloride salt catalyst (3.1 g, 0.2 μM), temperature reaction, when the mixture temperature reaches 95 - 96 °C when, begin to boil off ethanol (due to the reaction of the materials change, boil off ethanol initial temperature rise about 18 °C), when the 135 °C begins to boil off ethyl formate and alcohol mixture, has been slowly rising temperature to 180 °C, temperature control reaction 3 - 7 the H, then -0.07 mpa pressure reducing reaction 2 h, HPLC monitoring the reaction to the completion of the reaction, cooling to room temperature, adding isopropyl alcohol 200 ml stirring 1 h, filtration, solid 40 °C decompression drying 5 - 8 hours to obtain bis-amidine 128 g, yield 87.34%, purity 99.8%.

References:

CN107778200,2018,A Location in patent:Paragraph 0079-0104