The way dechlorination substituted compounds chloroaromatics

 

(57) Abstract:

The invention relates to a method dechlorination substituted chloroaromatics compounds by the action of a reducing agent (zinc, magnesium or aluminum) and catalytic amounts generated in situ complex compounds of Nickel with bidentate nitrogen-containing ligands (2,2'-BIPYRIDILIUM or 1,10 - phenanthroline) in the bipolar solvent in the presence of a source of protons at a temperature of 70-150C. as a result, the process is simplified and becomes cheaper, environmentally friendly, increase the yields of products. 8 table.

The invention relates to methods of dechlorination substituted chloroaromatics compounds of the formula

< / BR>
R1=R2=R3=R4=R5=H (1);

R1=R2=R4=5=H, R3=CH3(2);

R1=R2=R4=R5=H, R3= OCH3(3);

R1=R2=R4=R5H, R3=C2H5(4);

R2=R3=R5=H, R1=R4= CH3; (5);

R1=R2=R4=R5=H; R3=NH2(6),

R1=R2=R3=R4=R5=F (7);

R1=R2=R3=R4=R5=CH3(8)

R1=R2=R4=R5=H, R3=COCH3(11);

R1=R3=R5=F, R2=R4= Cl (12);

R1=R4, R2=R3=R5=Cl (13);

R1=R2=R3=R4=R5=Cl (14);

R1=R2=R4=R5=H, R3= C6H4Cl (15);

R1=R2=R4=R5=Cl, R3=C6Cl5(16)

R1=R2=R3=H, R4=R5= -CH=CH-CH=CH- (17);

R1=R2=R5= H, R4+R3= -CH=CH-CH=CH-(18);

R1=R2=R3=Cl, R4+R5= -CCl=CCl-CCl=CCl- (19).

The method can be applied in organic synthesis for the removal of the chlorine atom of the aromatic ring [J. Chem. Soc., Perkin Trans 1, 1973, p. 2509] , to obtain a practically significant aromatic compounds [Izv. An SSSR, ser. Chem. , 1963, S. 1524], and as a way of neutralizing the toxic polychromatically compounds [J.Org. Chem., 1991, V. 56, R. 6145].

The described method [Organometallics, 1991, V. 10, p. 1620], representing reductive dechlorination substituted chlorobenzene hydrogen at 25-80oC in the presence of rhodium complexes under conditions of phase transfer catalysis (Similar to 1). The reaction is carried out in a mixture of 40% aqueous alkali and toluene at a temperature of 25-80oC in t is).

< / BR>
R = H (1) - 97%*, CH3(o - (20)-7%, m - (21) - 95%, p - (2) - 97%), OCH3(22) - 99%, CF3(23) - 87%, NH2(6)-91%, COCH3(11) - 97%, COOH(10)-99%, COOPh (24)-98%.

Cy = cyclohexyl.

* - specified output dechlorination products (according to GC).

Circuit 1

The yields of target products defined by GLC, are 7-99%. Disadvantages of the method are the use of gaseous hydrogen and high cost of the catalyst.

Also described method [J. Mol. Catal. 1992, v.73, R. 173] dechlorination substituted chlorobenzene under the conditions of catalysis complex compounds of palladium using sodium formate or methanol as the reducing agent, the reaction is carried out in an aqueous alkali solution at a temperature of 100oC for 20 h (Analogue 2) (Scheme 2).

< / BR>
R = H (1)-90%* CHO(25)-100%, CN(26)-100%, NO2(27)-70%, COCH3(11)-87%, OCH3(3)-11%, NH2(6) -15%, CH3(2)-14%.

dippp = 1,3-bis(diisopropylamino)propane.

* - specified output dechlorination products (according to GC).

Scheme 2

The disadvantages of this method are the long time of the reaction and the high cost of complex compounds of palladium.

The closest analogue to the claimed solirovanie aryl halides proceeds under the action of metals (zinc, aluminum, calcium, magnesium) in the presence generated in situ from a salt of Nickel (II) and triarylphosphine (usually triphenylphosphine) complex compounds of Nickel. The reaction proceeds in a nitrogen atmosphere at 70oC for 1-2 h In the solvent used dimethylformamide, as a source of proton - water (Scheme 3).

< / BR>
R = H(1)-66%*, OCH3(3)-97%, CH3(2)-92%, CN (26)-90%, CH2OH (28)-97%.

* - specified output dechlorination products according to GC.

Scheme 3

The outputs of the dechlorination products range from 66 to 97%.

The disadvantage is the closest analogue is used as a catalyst complex compounds of Nickel with triphenylphosphine, which

- break down under the action of atmospheric oxygen, resulting in the dechlorination reaction is carried out in an inert atmosphere [J.Org. Chem. 1982, v.47, R. 2622, US 44004566 A, 1983, J.Org. Chem., 1986, v.51, p. 2627];

- interact with the free triphenylphosphine in reducing conditions, which leads to the destruction of triphenylphosphine during the reaction and the formation of the products of the cross-combination of arylhalides and triphenylphosphine [j.Kollman and other ORGANOMETALLIC chemistry of transition metals. M.:Mir, 1989];

- make up 30-70% of the mass of the substrate is of ACA of this invention is to provide a highly efficient, a more environmentally friendly way dechlorination substituted chloroaromatics compounds of structural formula

< / BR>
where R1=R2=R3=R4=R5=H (1);

R1=R2=R4=R5=H, R3=CH3(2);

R1=R2=R4=R5=H, R3= OCH3(3);

R1=R2=R4=R5=H, R3=C2H5(4);

R1=R3=R5=H, R1=R4= CH3(5);

R1=R2=R4=R5=H, R3=NH2(6),

R1=R2=R3=R4=R5=F (7);

R1=R2=R3=R4=R5=CH3(8)

R1=R2=R4=R5=HR=Cl (9);

R1=R2=R4=R5= H, R3=COOH (10);

R1=R2=R4=R5=H, R3=COCH3(11);

R1=R3=R5=F, R2=R4= Cl (12);

R1=R4=H, R2=R3=R5=Cl (13);

R1=R2=R3=R4=R5=Cl (14);

R1=R2=R4=R5=H, R3= C6H4Cl (15);

R1=R2=R4=R5=Cl, R3=C6Cl5(16)

R1=R2=R3=H, R4=R5= -CH=CH-CH=CH- (17);

R1=R2=R5= H, RoC. as the source of protons use water, salts of amines (ammonium chloride and triethylamine hydrochloride) and dilute solutions of inorganic (HCl) and organic (HCOOH and CH3COOH) acid.

The reducing agent is taken in a 2-3-fold molar excess relative to the substrate. The excess of reducing agent required for complete conversion of artilharia. At the same time, the upper limit is limited to 3-fold excess of zinc (magnesium, aluminum) to reduce the consumption of reducing agent.

The source of protons is used in a 2-3 fold molar excess relative to the substrate.

If you want to remove some of the chlorine atoms of the aromatic ring, the number of wastea, want to remove.

The amount of catalyst ranges from 0.01 to 0.5 mol for one mol of the substrate, the optimum range is from 0.01 to 0.1 mol. When using less than 0.01 mol of compound of Nickel on 1 mol of the substrate dramatically increases the time required for the complete conversion of the substrate, the use of more than 0.1 mol of catalyst leads to unnecessary increase in the consumption of reagents.

It should be noted that the reaction does not require the creation of an inert atmosphere.

The obviousness of the proposed solution of the task is illustrated by the currently available literature data. Thus, not described in literature using our proposed Nickel compounds as catalysts dechlorination reaction of substituted chlorobenzene, chlorobiphenyls and chloronaphthalene.

The invention is illustrated by the following examples:

Example 1.

In a flask equipped with a mechanical stirrer, reflux condenser and oil bath with an automatic thermostat, put 0,242 g (0.001 mol) of uranyl chloride Nickel, 0.156 g (0.001 mol) of 2,2'-bipyridine, 4 ml of dimethylformamide and 1.1 g of water (1.1 ml, 0.06 mol). The mixture is heated to 70oC and paramesh is stirred for another 30-40 minutes until black color. Add 4,06 g (0.02 mol) of pentafluorobenzene (7), the reaction mixture is stirred at 70oC 1 o'clock the Degree of conversion of the substrate determined by HPLC. Distilled from the reaction mixture of 3.03 g of pentafluorobenzoyl, collecting the fraction with TKip.=85-86oC.

The product yield of 90%.

Examples 2, 3 demonstrate the use as a reductant of magnesium and aluminum. Examples of 2.3. The reaction is carried out under the conditions of example 1, but as a reducing agent is magnesium (1.44 g, 0.06 mol) or aluminum (1,62 g, 0.06 mol). The results are shown in table 1.

Examples 4 to 9 show the effect of reductant.

Examples 4 to 9. The reaction is carried out under the conditions of example 1. Changes the ratio of the reducing agent (zinc, or aluminum, or magnesium)/substrate. The results are shown in table 2.

Examples 10-18 illustrate the impact of the number of catalyst.

Examples 10 to 18. The reaction is carried out under the conditions of example 1. Change the number of catalyst. The results are shown in table 3.

Examples 19-23 demonstrate the ability to use different sources of protons.

Examples 19 to 23. The reaction is carried out under the conditions of example 1. Changes the nature of the source of prot the ranks of inorganic compounds of Nickel to generate in situ complex compounds of Nickel 2,2'-BIPYRIDILIUM.

Examples 24 to 28. The reaction is carried out under the conditions of example 1. Modified inorganic compound of Nickel. The results are shown in table 5.

Examples 29-32 show the effect of temperature on the degree of conversion of the substrate.

Examples 29 to 32. The reaction is carried out under the conditions of example 1. Does the temperature of the reaction. The results are shown in table 6.

Example 33 shows the possibility of using as a catalyst generated in situ from uranyl chloride Nickel and 1,10-phenanthroline complex compounds of Nickel.

Example 33.

In a flask equipped with a mechanical stirrer, reflux condenser and oil bath with an automatic thermostat, put 0,242 g (0.001 mol) of uranyl chloride of Nickel, of 0.182 g (0.001 mol) of 1,10-phenanthroline, 4 ml of dimethylformamide and 1.1 g of water (1.1 ml, 0.06 mol). The mixture is heated to 70oC and stirred for 10 min before the appearance of green color.

Type of 3.9 g (0.06 mol) of zinc dust, the reaction mixture is stirred for another 30-40 minutes until black color. Add 4,06 g (0.02 mol) of pentafluorobenzene (7), the reaction mixture is stirred at 70oC 1 o'clock the Degree of conversion of the substrate determined by HPLC. Argonauta 92%.

Examples 34-37 show the possibility of using different solvents.

Examples 34-37. The reaction is carried out under the conditions of example 33. Changing the solvent. The results are shown in table 7.

Examples 58-78 demonstrate the possibility of using the proposed method for dechlorination substituted chlorobenzene (1-6, 8-14), chlorobiphenyls (15, 16) and chloronaphthalenes (17-19).

Examples 38 and 38. The reaction is carried out under the conditions of example 33. Changing nature chloroaromatics connection. The reaction products produce by conventional means. The results are shown in table 8.

Thus, the proposed method dechlorination substituted chloroaromatics connection allows you to:

to get the products dechlorination substituted chloroaromatics compounds in high yields without the formation of side products, which significantly simplifies the procedure of selection of target products;

- avoid the use of significant quantities of phosphine complexes of Nickel, which can significantly reduce the amount of toxic reaction;

- to refuse the use of inert atmosphere for the reaction and, thus, to simplify and cheapen the process of declare the ical compounds of the formula

< / BR>
where R1=R2=R3=R4=R5=H (1);

R1=R2=R4=R5=H, R3=CH3(2);

R1=R2=R4=R5=H, R3=OCH3(3);

R1=R2=R4=R5=H, R3=C2H5(4);

R2=R3=R5=H, R1=R4=CH3(5);

R1=R2=R4=R5=H; R3=NH2(6);

R1=R2=R3=R4=R5=F (7);

R1=R2=R3=R4=R5=CH3(8);

R1=R2=R4=R5=H, R3=Cl (9);

R1=R2=R4=R5=H, R3=COOH (10);

R1=R2=R4=R5=H, R3=COCH3(11);

R1=R3=R5=F, R2=R4=Cl (12);

R1=R4=H, R2=R3=R5=Cl (13);

R1=R2=R3=R4=R5=Cl (14);

R1=R2=R4=R5=H, R3=C6H4Cl (15);

R1=R2=R4=R5=Cl, R3=C6Cl5(16);

R1=R2=R3=H, R4+ R5=-CH=CH-CH=CH- (17);

R1=R2=R5=H, R4+ R3=-CH=CH-CH=CH- (18);

R1=R2=R3=Cl, R4+ R5=-CCl=CCl-CCl=CCl- (19)

the action is and Nickel and ligand, in the environment of the bipolar organic solvent, characterized in that as a ligand using 2,2'-bipyridyl and 1,10-phenanthroline.

 

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