Method of preparing integral generation polypropyleneimine dendrimer by reducing cyano group

Abstract

The invention discloses a method of preparing a primary amine compound by reducing a cyano group. The method is characterized in that the primary amine compound is integral generation PPI (Polypropyleneimine) dendrimer. The method comprises a step of reducing half generation PPI dendrimer in alkaline solution with sodium borohydride under normal pressure by taking Raney Ni as a catalyst under an alkaline condition, wherein the reaction is performed in the solution; the mass ratio of the Raney Ni to the half generation PPI is 1:1-7.5:1; and the molar ratio of the sodium borohydride to the cyano group in the half generation PPI is 1.5:1-4:1. The preparation method can be performed under normal pressure; and a product has the advantages of high yield and high primary amine content.

Description

technical field [0001] The invention relates to a method for preparing primary amine compounds, in particular to a method for reducing cyano groups to prepare primary amine compounds. Background technique [0002] Polypropyleneimine (PPI) dendrimers have high regularity, there are a large number of cavities inside the molecule, and there are multiple amino groups on the surface of the molecule. The unique chemical structure makes polypropyleneimine (PPI) widely used in medicinal chemistry, photosensitive materials, nano Materials and catalysis have broad application prospects. At present, the relatively mature synthesis method of PPI is to take diamine as the central core and acrylonitrile as the repeating unit, and alternately repeat the Michael addition reaction (Michael Addition, N-alkylation) and the hydrogenation reduction reaction of polynitriles to obtain Half-generation PPI (0.5G PPI, 1.5G PPI, etc.) with a cyano group at the end and an integer generation of PPI wit...

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Problems solved by technology

[0003] In the prior art, the reaction of multi-component nitriles being reduced to primary amines under the action of a catalyst needs to be carried out under high-pressure environment. For example, a prior art adopts Raney Ni to hydrogenate nitriles in alkaline solution to generate amine compounds, which has a higher Catalytic activity, but a certain amount of by-product secondary and tertiary amines are also generated in the reaction, and the reaction needs to be carried out under a higher pressure (6MPa), and the reaction time is longer (24h) (low generation polypropylene Synthesis and characterization of imine dendrimers, Fine Chemical Industry, 2001, 18(7), 414-416)

There is also a kind of reduction system (Wang Qin, Chemical Reagent, 2005, 27 (1), 8-10) that a kind of prior art is polycyano compound with Urushihara cobalt and 1,4-dioxane-water (10%) , although the yield of the reaction and the proportion of primary amines are higher, the reaction still needs to be carried out under a higher pressure (3MPa)

Another prior art uses Raney Co-Cr and water as a reducing system (Meijler, Angew.Chem.Int.Ed.Engl., 1993, 32:1306-1308), successfully realizing the conversion of polyvalent nitriles to primary amines , the product does not need to be separated, and the yield of primary amine is high, but the reaction also needs to be carried out under a relatively high pressure (4MPa), and the price of Raney Co is expensive, and it is not easy to obtain from the domestic market

[0004] In the prior art, there is also the use of hydrogenation reduction under normal pressure, such as the use of sodium borohydride and cobalt (II) salts to reduce polyhydric nitriles (Vogtle, Angew.Chem.Int.Ed.Engl., 1992, 31: 1571-1576 ), easy to produce side reactions that lead to the disconnection of aminoethyl or aminopropyl side chains in the reaction process, making the product difficult to purify, and the yield of primary amine is very low

[0005] In the prior art of the synthesis of the above polypropyleneimine (PPI) dendrimers, catalysts Ni and Co are used to reduce multi-valent nitriles to primary amines through high-pressure catalytic hydrogenation, which requires higher pressure (>3MP) in the hydrogenation reaction And longer reaction time (24h), relatively high requirements for reaction equipment, and there are side reactions in the reaction process, the yield of primary amine is low, and the product is not easy to purify

[0006] The successful preparation of 2.0-generation integer-generation polypropyleneimine (PPI) dendrimers under atmospheric pressure has not yet been reported

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