DE1693039A1 - Process for the production of malonic dinitrile - Google Patents

Description

PATENT ADVOCATE TELESITAMME: WESPATENT g MUNICH 19

ROSTSCHECK: MONCHEMUtet «MOHTENSTHASSE t / l

• ANKHAUS H. AUFHAUSE * 10031 TELEPHONE: * 7 32 OS

ARTHUR D. LITTTE, INC., 20 Acorn Park * Cambridge Massachusetts, U.S.A. Process for the production of malononitrile

The present invention relates to the manufacture of Malononitrile. *

Malononitrile, _CH2 (CN) ₂ * Those is mainly as starting materials or intermediates in the preparation of a number of organic compounds and {Particularly, in the synchronous% of drugs and medicines, "such as barbiturates, as well as Voe in riot Beicämpfungsgasen benzaldehyde -Type used.

According to the invention, practically the same molar ratios of HCN and Cl _{2 are} reacted, and the product "ClCN and HCl" is then brought into contact with acetonitrile at an elevated temperature in order to obtain the desired CH ₂ (CN) ₂ . The HCl formed as a by-product is discharged and later removed.

1098 * 0/1763. _BATH

To date, malononitrile has been produced by reacting acetonitrile with cyanogen chloride (US Pat. No. 2,555,406) or with hydrogen cyanide (US Pat. No. 3,055,758): From these methods the route using cyanogen chloride evidently gives a much better yield (18 %). theory) than the route using hydrogen cyanide (maximum 4.6 %}. However, the previous method requires the synthesis of cyanogen chloride and its isolation and purification prior to its use in the synthesis of malononitrile. These additional steps increase the cost of the production of Malononitrile significantly and bring problems with the handling of the reaction intermediates, since they are all toxic and corrosive.

It would therefore be desirable to have a process for the production of malononitrile as a single Procedures could be performed so as to avoid the isolation of intermediates.

It is therefore a primary object of the present invention to provide a To provide a process for the manufacture of malononitrile that essentially uses a single integrated process two separate reactions are carried out in succession without the need for isolation and purification of any of the Tests to be carried out «Another goal is the Creation of a process of the type described above that good yields of malononitrile. Other goals of the invention will be apparent from the description below. 109840/1753

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The present invention also relates to the various stages and the relationship of one or more of these stages to one another. The invention will now be explained in more detail below.

For the sake of clarity, the reactions involved in the preparation of malononitrile according to the invention can be written as two stages * but it should be noted that they are carried out one after the other in a device that is to be regarded as the only piece of equipment .

HCM + Cl ₂ ► ClCN + HCl (1)

ClCM + CH ₃ CM ψ CH ₂ (CM) ₂ + HCl (2)

Reaction (1) proceeds quantitatively with formation of ClCM at about 2CX) ^- C over a carbon catalyst and no appreciable amount of cyano (CN) _{2 is} formed. For this reason it is preferable to start with practically equal solar amounts of HCN and Cig. When the gas flow of ClCN overall {forms is "it is (zusanswm nlt dea by-product HCl) conducted in a quartz reaction tube. At the same time, acetonitrile, C3UCM "is introduced into the quartz tube at the top end" and the reaction components of the susuMm-tiling oase currents react by keeping the quartz furnace at 700 ° C. after the reaction. (2) to form the gewUnach-

ten malononitrile ·. Xein decomposition product and no « Decomposition products from lifting reactions was or were

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found in the product stream. That formed as a by-product Has HCl in the reaction stream entering the quartz tube, as far as could be ascertained, no adverse effects on the performance of the reaction "

The following example explains the invention without restricting it.

W. example

Gaseous HCN and Cig were in an equimolar ratio with at a rate of 45 com / minute (NTP) is introduced into a first reaction vessel, which consists of a 15 cm long Pyrex tube with an outside diameter of 10 existed, activated 10 ecm Contained coconut charcoal and was cooled at a temperature of 200 * C in a thermally regulated tubular oven. the The flow time through this first reaction vessel was 6 seconds. The oasis of the ClCN produced and the HCl formed as a by-product were then introduced into one end of a quartz tube which had an effective volume of 26 ecm and was kept at a temperature of 700 ° C by a second heat-regulated tube furnace. 3.9 g of acetonitrile were was introduced into the quartz reaction tube, and the flow time through this second reaction tube was about 5 seconds. . The gas from the quartz tube was kept at 0 ° C PyiQX pallen spawned, and malononitrile produced there • Was quantitatively carried out in the acetonitrile solution obtained Spectroscopy is staring. Dl * amount of recovered «

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169303d

Acetonitrile was 3.5 g and the amount of product CH ₂ (CN) ₂ 0 * 56 g. The conversion of the acetonitrile was thus 10 $> · The unreacted acetonitrile can be returned to the process after topping up * The yield of malononitrile, based on the limiting HCN introduced into the reaction system, was 87%.

Although somewhat lower reaction temperatures can be used, this affects the final yield of malononitrile somewhat. ^{For example, temperatures between 100 and 250 °} C. in the first reaction vessel and temperatures between 600 and 750 ° C. in the second reaction vessel can be used. The reactions are preferably carried out at atraospheric pressures, but superatmospheric pressures can also be used.

In general, the residence time of the reaction components is 4 to 10 seconds in the first reaction vessel and 3 to 8 seconds

Seconds in the second reaction vessel. "

It can be seen that the objectives set out above, as well as those resulting from the description, are more effective Way were achieved.

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Claims (3)

1693Q39 claims 1. Process for the preparation of malononitrile *, characterized in that * (a) contains gaseous hydrogen cyanide and chlorine in virtually equimolar ratios in a first reaction tube, the activated carbon, are reacted at a temperature between about 100 and 25O ⁰ C * (b) the cyanogen chloride produced and the hydrogen chloride formed as a by-product, as well as an excess of acetonitrile are introduced into a second * at a temperature between about 600 and '750 * C held reaction tube and so malononitrile is formed * (c) the gaseous reaction stream from each reaction tube ) is deducted and (d) the malononitrile formed is recovered. 2. The method according to claim 1 * characterized * that the temperature in the first reaction tube at about 200 * C and in the second reaction tube is kept at about 700 ° C. 3. The method according to claim 1 *, characterized in that the residence time of the reaction components is 4 to 10 seconds in the first reaction tube and 3 to 8 seconds in the second reaction tube * 109840 / 17S3 BAD ORKäfNAL