CA1151669A - Hydrocyanation of activated olefins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Nitriles are prepared by contacting an activated olefin, e.g. methyl acrylate, with gaseous hydrogen cyanide in the presence of a catalyst containing an element selected from the group consisting of Group IA and IIA.

Description

~iS~6 9 (5177) BACKGROUND OF THE INVENTION
This lnvention relates to a novel process for the ~ talytic addition of gaseous hydrogen cyanide to activated olefins.
There are several known methods ~or hydrocyanating un~ctivated olefins in the vapor phase. Teter, U.S. Patent

2,385,741, describes the addition of hydrogen cyanide to unactivated olefins in the presence of a finely-divided metallic cobalt catalyst. Darvis, U.S. Patents 3,278,575 and 3,278,576, discloses that finely-divided metallic nickel ; or palladium can also be employed to catalyze the addition of hydrogen cyanide to unactivated olefins. The highest ,yield of organic nitriles obtained by any o~ these processes is 42%.
Furthermore, it is also known in the prior art, i.e. Cordar U.S. Patent 2,904,581, that organic nitriles can be prepared ~rom actlvated olefins.. Activated olefins are hydrocarbons whlch contain an actlvatlng group in close proximity to an olefinic carbon atom. Preferably, this activating ~roup is ad~acent to an olefinic carbon. Yields as high as 80% have been obtained by this process. ~nfor-tunately, this is a liquid phase process and both hydrogen cyanide and the activated olefin tend to polymerize at the disclosed reaction conditions. Also, it is very difficult to separate the homogeneous catalyst from the reaction product.
The inventive process results in much higher yields of organic nitriles than the prior art vapor phase processes. Furthermore, these higher y~elds are accom-plished at substantially lower temperatures. , Finally, since the inventlve process is conducted in the vapor phase the 1 ~5 ~ g (5177~

hydrogen cyanide and activated olefin polymerlzation problem is e~iminated.

SUMMARY OF THE INVENTION
It has now been discovered that nitriles can be pr~uced by contactin~ an activated olefin with gaseous hydrogen cyanide in the presence of a catalyst containing at least one element selected from the group consistlng of Group IA and IIA of the Periodic Table.
In partlcular, the inventive process results in high yields of cyanoesters when alpha, beta-unsaturated alkyl acrylates are contacted with gaseous hydrogen cyanide in the presence of a catalyst containing an alkali metal.

DETAILED DESCRIPTION
According to the present invention, nitriles are produced by the catalytic addition Pf hydrogen cyanide to activated olefins. The overall reaction taking place in this process is represented by the following equation:
12 ~3 12 13 C = C - X + HCN NC - C - C - X
Rl Rl H
wherein Rl, R2, R3 and X are defined below.
Nitriles are well known organic chemicals having a wide variety of uses as solvents and the like. They are also important intermediates for the preparation of a broad spectrum of organic chemicals as described, for example, in the text "The Chemistry of Organic Cyanogen Compounds" by V. Migridichian, American Chemical Society Monograph No.
105, Reinhold Publishing Company (New York, 1947).

115~669 (5177) Reactants The preferred activated ole~ins which can be employed in thls ~nvention are any compound of the general formula:

C = C -- X
Rl wherein Rl, R1 and R3 are each independently selected from the group consisting of:
10(1) hydrogen;
(2) Cl_4 alkyl;

(3) aromatic hydrocarbon radical;

(4) alicyclic hydrocarbon radical;

(5) aralkyl hydrocarbon radical;

(6) -(CH2)n-C-OR4, wherein R4 ls hydrogen or a Cl 4 alkyl and n is 0 to 4; and O .

(7) -(CH2)S-C-R5, whereln R5 ls hydrogen or a Cl 4 alkyl and s ls 0 to 4;
and wherein X ls selected from the group consisting of:

(1) -(CH2)t-C-OR6, wherein R6 is hydrogen or a Cl-12 alkyl and t is 0 to 2;
) (CH2)U-CN, wherein u is 0 or 1; and (3) -(CH2)V-C-R7, wherein R7 is hydrogen or a Cl 12 radical and v is 0 to 2.
Examples of these activated olefin include acrolein, meth-acrolein, acrylonitrile, methacrylonitrile, methyl acrylate and ethyl acrylate.
Preferably, Rl, R2 and R3 are each independently selected from:

~5~ ( 5177) (1) hydrogen;
(2) Cl_4 alkyl, and X ls selected from the group conslsting of:

(1) -C-OR6s wherein R6 is H or Cl 4 alkyl;
(2) -CN;

(3) -C-R7, wherein R7 is H or Cl 4 alkyl.
More preferably, the oleflnlcally unsaturated com-pounds comprise compounds wherein Rl, R2 and R3 are each independently selected from hydrogen and methyl and wherein O O
X ls -C-OH and -C-OCH3 The activated olefin is contacted with gaseous hydrogen cyanide to produce the cyanoester. The ratio of the olefln to hydrogen cyanide is not crltical. The lnstant reaction wlll proceed with elther excess olefln or excess hydrogen cyanlde. However, the use of excess activated olefln is prererred, since thls minimizes the loss of HCN.
Accordln~ly, it is pre~erred to employ a molar ratio of activated olefln to HCN of greater than one and preferably between about one to ten.
If deslred, a carrier gas whlch is inert to the reactants, products and catalysts can be included in the reaction system. Thus, gases such as nitrogen, the noble gases, lower alkanes, carbon monoxide, carbon dloxide, ammonia and minor amounts o~ hydrogen sulfide can be added to the reaction system.
Process Conditions In carrying out the inventive process, the acti-vated olefin and hydrogen cyanide in the vapor phase are contacted with a catalyst as described below. This process is preferably conducted on a continuous basis but lt can (5177) also be accomplished in a batch mode. Elther ~ixed and fluid catalyst beds can be used.
The reaction temperature is normally maintained between 40C and 350C, prererably 150C to 300C. The reaction pressure is normally maintained at 0 to 100 psi, pre~erably 10 to 40 psl. When the process is carried out in the continuous basis, the Gontact time is normally ten seconds to ten minutes, pre~erably 10 seconds to 5 minutes.
When the reaction is carried out in a batch mode, reactants and catalysts are contacted with one another for a period of 10 minutes to 6 hours, preferably 1/2 hour to 4 hours. A
reactlon time o~ less than 10 minutes or more than 6 hours can be used if desired, although better results will be ob-tained if the reaction time is maintained within thls range.
Catalyst The heterogeneous catalyst employed in thls pro-cess comprises at least one elemen~ selected from the group consistlng of Group IA and IIA of the Periodic Table.
Preferred catalysts comprise at least one of K, Li, Cs, Ca, Ba and Mg. Especially preferred catalysts contain at least one of K, Li and Cs. This catalyst can be promoted with a wide variety of metals selected rrom groups VIB, VIIB, VIII
and IB. Preferred promoters include Ru, Cr, ~, Cu, i~i and rri .
The instant catalyst is primarily a compound of a ïnetal capable of withstanding the temperatures employed.
These various metal compounds include oxides, hydroxides, and various salts, e.g. ferrocyanides, phosphates, carbon-ates, silicates, aluminates, cyanides and salts o~ organic acids such as the acetates, formates and butyrates. Pre-ferred catalysts contain oxygen or oxygen-containing anions.

1~5~669 (5177) The free metals may also be used. Compounds which are somewhat basic in nature or which at least in part react with hydrogen cyanide to rorm metal cyanides have been found to be particularly good.
The catalyst can be prepared by methods well known n the art. For example, these catalysts can be produced by evaporating a solution o~ a soluble compound on an inert carrier, or mixing an aqueous slurry of an insoluble com-pound or Or the free metal with an inert carrier, riltering, pressing, drying and calcinlng the filter cake; and rinally grinding the filter cake to the desired particle size. The inert carriers which may be used with this catalyst include aluminates, silicates, titanates and phosphates and mixtures thereof. Preferred carriers are aluminates and silicates.
Basic compounds such as quartz, diatomaceous earth, various clays and pumice may also be used.
Reco~y The reaction product obtained upon completion of this reaction are partially in the gas phase. Thls reaction product can be sub~ected to suitable known separation tech-niques to obtain the desired end product.
For example, the product can be condensed to a liquid. The liquid product can then be ~iltered to remove catalyst therefrom and then separated into component parts by the use Or solvent extraction and distillatlon.

SPECIFIC EMBODIMENTS
In order to more clearly illustrate the present invention, the following working examples are presented. In these examples, the ~ollowing definition is used:
Yield = Moles of Nitrile Product Formed Moles Or HCN Fed 1~5~ i9 Example 1 A catalyst comprising 7.6% LioAc on a low surface area alumina was prepared as follows. First, 4.11 grams of LiOAc were dissolved in 20 grams of water. Next, 50 grams of a low surface area alumina, i.e. alumina with a surface area of less than 5 square meters per gram, were stirred into the lithium solution. This mixture was dried for 15 hours at 125C and calcined for 16 hours at 350C.
40 cc. of the above catalyst were packed into a reactor. A furnace heated the reactor while nitrogen flowed over the catalyst bed. When the reaction temperature reached 250C, the gas was changed to a mixture of 7% to 10% HCN in nitrogen, and the system was allowed to equili-brate for 15 minutes. Methyl acrylate was then pumped in at a rate of 10 cc. per hour. The output of the reactor was passed to a pair of dry ice cooled glass condensors, and the product was collected. The product was warmed to room temperature, weighed and analyzed. The results are shown in Table I.

Example 2 A catalyst comprising 11.2 weight percent KNO3 on a low surface area alumina was prepared as follows. First, 6.31 grams of KNO3 were dissolved in 20 grams of water.
Next, 50 grams of a low surface area alumina, i.e. alumina with a surface area of less than 5 square meters per gram, were mixed with the aqueous potassium solution. This mix-ture was dried for 15 hours at 125C and calcined for 5 hours at 260C and 15 hours at 538C.
The catalyst prepared above was placed into the experimental apparatus described in Example 1. The results are shown in Table I.

5 16~ ~

(5177) Examples 3 thru 5 Other catalysts containing Group IA or Group IIA
elements were prepared by the techniques described in Example 2. These catalysts were also placed in the experimental apparatus described in Example 1 and ~he results are shown ~n Table I.
Fxample 6 A catalyst comprising MgA12O4 was prepared as follows. First, 85.47 grams of Mg(N03)2-6H2o were dissolved in water. Next, 33.99 grams of A1203 powder were slurried in water. These two aqueous solutions were mixed together and evaporated to the consistency of toothpaste. The mix-ture was then dried for 15 hours at 125C and calcined 5 hours at 500F and 20 hours at 1,000F. Thls catalyst was placed in the experlmental apparatus descrlbed in Example 1 and the results are shown ln Table I.
Examples 7 and 8 Catalysts contalnlng potasslum were prepared by the technique described in Example 6. These catalysts were also placed ln the experimental apparatus descrlbed ln Example 1 and the results are shown in Table I.
~xample 9 .

A catalyst comprising 23.78 weight percent of KMn(CN)6 on a low surface area alumina was prepared as rollows. First, 15.6 grams of KMn(CN)6 were dissolved in 20 grams of water. 50 grams of a low surface area alumina were mixed with this aqueous solution. The mlxture was then dried for 15 hours at 125C and calcined for 3 hours at 350C. This catalyst was placed in the experimental appar-atus described in Example 1 and the results are shown in Table I.

~i.5~669 (5177) Examples 10 thru 12 Other catalysts containlng potasslum were prepared and placed in the experimental apparatus described in Example 1. The results are shown in Table I.

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~I N

~lSl~;69 (5177) Examples 13 thru 18 A catalyst comprising CaA12O4 was prepared as follows. First, 78.72 grams of Ca(NO3)2 4H2O were dissolved in water. Also, 33.99 grams of A12O3 powder were slurried in water. These two aqueous solutions were mlxed together and evaporated to the consistency of toothpaste. Thls mix-ture was then dried for 15 hours at 125C and calcined for 5 hours at 500F and 20 hours at 1,000F. The catalyst was then placed in the experimental apparatus described in Example 1 except that the process conditions were ad~usted as shown in Table II. The results of these experimental are shown in Table II.
Examples 19 thru 22 Other catalysts were also tested under various process conditions. These results are shown in Table II.

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0 ~ L~ o L~
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13 .

~5 1~ 9 (5177) Examples 23 thru 25 The catalyst and experimental apparatus shown in Example 2 were used in these examples. Three different activated olefins were tested and each of them yielded some nltrile. The results are shown in Table III.

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llS~669 (5177) Although only a few embodiments of this invention have been specifically described above, it should be appre-ciated that many additions and modirications can be made without departing from the spirit and scope of the inven~
tion. These and all other modifications are intended to be included within the scope of thls lnvention, which is to be limited only by the following claims:

Claims (18)

WE CLAIM:

1. A process for producing nitriles comprising contacting an activated olefin represented by the following formula:
wherein R1, R2 and R3 are each independently selected from:
(1) hydrogen;
(2) C1-4 alkyl;
(3) aromatic hydrocarbon radical;
(4) alicyclic hydrocarbon radical;
(5) aralkyl hydrocarbon radical;

(6) -(CH2)n-?-OR4, wherein R4 is either H or a C1-4 alkyl and n is 0 to 4; and (7) -CH2)s-?-R5, wherein R5 is either H or a C1-4-alkyl and s is 0 to 4;
and wherein X is selected from the group consisting of:

(1) -(CH2)t-?-OR6, wherein R6 is either H or a C1-12 alkyl and t is 0 to 2;
(2) -(CH2)u-CN, wherein u is 0 to 2; and (3) -(CH2)v-?-R7, wherein R7 is either H or a C1-12 alkyl and v is 0 to 2;
with gaseous hydrogen cyanide in the presence of a catalyst containing at least one element selected from the group con-sisting of Groups IA and IIA of the Periodic Table.

(5177)

2. The process of claim 1 wherein R1, R2 and R3 O
are selected from the group consisting of -C-OR4, wherein R4 is either H or a C1-4 alkyl.

3. The process of claim 1 wherein R1, R2 and R3 are each independently selected from H and C1-4 alkyl.

4. The process of claim 3 wherein R1, R2 and R3 are each independently selected from H and CH3.

5. The process of claim 1 wherein X is selected from the group consisting of:

(1) , wherein R6 is either H or a C1-4 alkyl;
(2) -CN; and (3) , wherein R7 is either H or a C1-4 alkyl.

6. The process of claim 5 wherein X is or .

7. The process of claim 1 wherein the molar ratio of activated olefin is between 1:1 and 2:1.

8. The process of claim 1 wherein the catalyst is heterogeneous.

9. The process of claim 1 wherein the reaction temperature is between 150°C and 300°C.

10. The process of claim 1 wherein the reaction pressure is between 10 psi and 40 psi.

11. The process of claim 1 wherein said catalyst comprises a mixture of Group IA and Group IIA elements.

12. The process of claim 1 wherein the catalyst comprises at least one Group IA element.

13. The process of claim 1 wherein the catalyst comprises at least one Group IIA element.

(5177)

14. The process of claim 1 wherein the catalyst comprises at least one of Li, Na, K, Rb, Cs, Mg, Ca, Sn and Ba.

15. The process of claim 1 wherein the catalyst is supported on an inert carrier.

16. The process of claim 15 wherein the carrier is alumina, silica or alumina silicate.

17. The process of claim l wherein a cyanoester is produced.

18. A process for producing a cyanoester com-prising contacting an alpha, beta-unsaturated alkyl acrylate with gaseous hydrogen cyanide in the presence of a catalyst containing an alkali metal component.