JPS6341384B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a nitrile from an N-monosubstituted formamide, and more particularly to a method for producing a nitrile in one step by dehydration and rearrangement of an N-monosubstituted formamide. Although it is known that the corresponding isonitrile can be obtained by dehydrating N-monosubstituted formamide, a method for directly producing a nitrile has not been well known. Recently, a method for producing nitriles from formamide using bismuth phosphomolybdate as a catalyst has been reported (ACS/CSJ
Preprint PETR 82, 1979), but the inventors also
-While researching the reaction of monosubstituted formamides, we discovered a method for obtaining nitriles in high yield and high selectivity, and arrived at the present invention. That is, the present invention provides 300% of N-monosubstituted formamide in the presence of an oxygen-containing gas and a catalyst consisting of one or more selected from oxides of metals of Groups and Groups of the Periodic Table and silica gel. A method for producing nitrile from formamide, characterized by processing at a temperature in the range of ~600°C. The method of the present invention can be simply expressed by the general formula for monoformamide as follows. RNHCHO( _O2 ) --→ _-H2O [RN=C]→R-C≡N i.e. N-monosubstituted formamide dehydrates in the presence of catalyst and oxygen, possibly via isonitrile as an intermediate. , and then R rearranges to give a nitrile.
This reaction is thought to proceed via the isonitrile represented in [ ], but is characterized by the fact that a nitrile having the same number of carbon atoms can be obtained from formamide in one step. Therefore, the number of carbon chains increases by one compared to the original formamide. It is thought that a similar reaction occurs with diformamide and triformamide as with monoformamide. Group metal oxides and silica gels used as catalysts in the present invention include:
V ₂ O ₃ , VO ₂ , V ₂ O ₅ , NbO, NbO ₂ , Nb ₂ O ₅ ,
Ta ₂ O ₅ , Sb ₂ O ₃ , Bi ₂ O ₃ , CrO, Cr ₂ O ₃ , MoO ₂ ,
Examples include MoO ₃ , WO ₂ , WO ₃ , W ₂ O ₅ , SiO ₂ and the like, but of course oxides in other oxidation states may also be included. These metal oxides can be used alone or in combination of two or more. Moreover, it is also possible to use as a catalyst a mixture of these metal oxides with other metals or metal oxides which may or may not be active as catalysts, if necessary. Among these metal oxides, molybdenum oxide, tungsten oxide, vanadium oxide, and silica gel are particularly preferably used as catalysts. Moreover, in the case of silica gel, silica gel heat-treated in air at 600 to 1000°C is particularly preferable. The heat treatment time is preferably several tens of minutes to several hours. Although these catalysts may be supported on a carrier, it is more preferable to use them without a carrier. The N-monosubstituted formamide used as a starting material in the present invention is represented by the general formula R(-NHCHO) _o , where n represents an integer from 1 to 3. Further, R means an n-valent organic residue, and represents a group selected from substituted or unsubstituted aliphatic groups, alicyclic groups, aromatic groups, and aralkyl groups. Substituents include those that decompose under reaction conditions,
It may be anything as long as it does not cause side reactions. For example, chlorine, fluorine, nitrile group, alkyl group, alkoxy group, acyl group,
N-monosubstituted formamides having substituents such as ester groups can be used in the present invention. As unsubstituted N-monosubstituted formamide,
For example, N-methylformamide, N-ethylformamide, N-propylformamide, N-butylformamide, N-bentylformamide,
N-hexylformamide, N-heptylformamide, N-octylformamide, N-nonylformamide, N-decylformamide, N-undecylformamide, N-dodecylformamide, N-octadecylformamide, N-isopropylformamide, N-isobutylformamide , N-alkyl monoformamides such as N-t-butylformamide and N-neopentylformamide; N-cyclopentylformamide, N-
N-alicyclic monoformamides such as cyclohexylformamide and N-methylcyclohexylformamide; N-phenylformamide, N-naphthylformamide, N-pyridylformamide,
N-aryl monoformamides such as N-indenylformamide, N-triazinylformamide, N-tolylformamide, N-quinolylformamide, N-oxazolylformamide; N-
N-aral monoformamides such as benzylformamide and N-phenethylformamide; N,
N'-ethylene diformamide, N,N'-trimethylene diformamide, N,N'-tetramethylene diformamide, N,N'-hexamethylene diformamide, N,N'-octamethylene diformamide, N,N N,N'-alkylene diformamides such as '-undecamethylene diformamide and N,N'-dodecamethylene diformamide;
N,N'-1,4-cyclohexyldiformamide, N,N'-1,4-dimethylcyclohexylformamide, N,N'-isophorone diformamide, N,N'-cyclohexylmethylene diformamide, N,N'- N,N'-alicyclic diformamides such as 4,4'-dicyclohexylmethane diformamide; N,N'-1,4-phenylene diformamide, N,N'-2,4-tolylene diformamide, N,N'-2,6-tolylene diformamide, N,N'-4,4'-diphenylmethane diformamide, N,N'-4,4'-diphenyl ether diformamide, N,N'- N,N'-aryl diformamides such as 1,4-naphthylene diformamide, N,N'-1,5-naphthylene diformamide, N,N'-2,6-naphthylene diformamide; N,N'- Examples include monoformamides and diformamides such as N,N'-aralkylene diformamides such as xylylene diformamide. In addition, triamines such as 1,
8-diamino-4-aminomethyloctane, 1,
Triformamides such as 2,3-triaminopropane, melamine, tris(2-aminoethyl)amine can also be used in the present invention and can be converted to the corresponding triisocyanates. Of course, formamides obtained by substituting these unsubstituted formamides with the above-mentioned substituents can also be used. For example, formamide, which is an ester derivative of an amino acid, can also be used. These include formamides such as methyl and ethyl esters of alanine, valine, and leucine; formamides such as dimethyl and diethyl esters of aspartic acid and glutamic acid; diformamides such as methyl and ethyl esters of lysine; Diformamides such as 2-aminoethyl ester of valine and leucine; di(2-aminoethyl) of aspartic acid and glutamic acid
Triformamide such as ester; 2- of lysine
Examples include triformamide such as aminoethyl ester. These N-monosubstituted formamides can be easily obtained by reacting the corresponding primary amine with a formic acid derivative such as a formic acid ester such as methyl formate or ethyl formate, or by reacting a primary amine with carbon monoxide. However, it may of course be manufactured by other methods. Since the nitriles obtained by the method of the present invention are easily converted into primary amines by hydrogen reduction, if the starting material N-monosubstituted formamide is produced from the corresponding primary amine,
By using the method of the present invention as an intermediate, a primary amine having a larger number of carbon atoms can be easily produced from a primary amine. That is, it is possible to produce a monoamine with an increased number of carbon atoms by 1 from a monoamine, a diamine with an increased number of carbon atoms of 2 from a diamine, and a triamine with an increased number of carbon atoms of 3 from a triamine. The oxygen-containing gas used in the present invention includes a predetermined amount of oxygen, and may be air or other gas that does not inhibit the reaction, such as inert gas such as nitrogen, argon, helium, carbon dioxide, etc. It may also be pure oxygen diluted with gas. In some cases, hydrogen, carbon monoxide, hydrocarbons,
It may also contain gases such as halogenated hydrocarbons. Although the reaction of the present invention proceeds to some extent even in the absence of oxygen, the presence of oxygen greatly improves the yield and selectivity of the nitrile, and also eliminates the deterioration of the activity of the catalyst over time. effective. The ratio of N-monosubstituted formamide and oxygen supplied onto the catalyst is 0.001 to 50 equivalents, preferably 0.01 to 10 equivalents of oxygen per formamide group. If the amount of oxygen is too small, the yield and selectivity of nitrile will not increase, and if it is too large, oxidative decomposition,
This is because combustion occurs and the yield of nitrile decreases. It is also a preferred method to dilute the reaction system with an inert gas such as nitrogen, argon, helium, carbon dioxide, etc. In this case, these inert gases are also used as carriers for the raw materials. The N-monosubstituted formamide supplied to the reaction system may be as is or may be diluted with an inert solvent. Examples of such solvents include hydrocarbons such as benzene, toluene, xylene, biphenyl, pentane, hexane, cyclopentane, cyclohexane, methylcyclohexane, tetralin, decalin, methylnaphthalene, benzonitrile, trinitrile, adiponitrile, valeronitrile. , nitriles such as butyronitrile, esters such as ethyl acetate, octyl acetate, and octyl propionate, and halogenated hydrocarbons such as chlorobenzene and dichlorobenzene. The temperature range used in the method of the invention is:
A temperature of 300 to 600° C. is preferred, depending on the catalyst system used, the type of N-monosubstituted formamide and its proportion with oxygen, and reaction conditions such as the concentration of formamide in the gas stream, residence time, and gas velocity.
This is because at a temperature lower than 300°C, the reaction hardly proceeds, and at a temperature higher than 600°C, side reactions such as decomposition occur, resulting in a decrease in the yield and selectivity of nitrile. The reaction for producing a nitrile from N-monosubstituted formamide according to the method of the present invention can be carried out either continuously or batchwise, but it is preferable to carry out the reaction continuously, and more preferably to produce a nitrile from N-monosubstituted formamide in a gaseous state. This is a so-called gas phase flow reaction method in which oxygen and oxygen are brought into continuous contact with the catalyst layer. Also preferred is a fluidized bed system in which gaseous N-monosubstituted formamide and oxygen are supplied from below the powdered catalyst layer. The contact time with the catalyst is preferably 0.05 to 100 seconds,
Furthermore, 0.1 to 20 seconds is more preferable. The reaction is usually carried out under normal pressure, but may of course be carried out under reduced pressure or increased pressure. In particular, when N-monosubstituted formamide having a high boiling point is used, it is preferable to carry out the reaction under reduced pressure in order to vaporize it at a temperature in the range of 300 to 600°C. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. These examples were generally performed in the following manner. A quartz reaction tube with a length of 40 cm and a diameter of 2 cm was
The reaction was carried out in a flow-through type reactor in which the catalyst layer was fixed in a vertical electric furnace with a catalyst layer located approximately at the center, and raw materials and oxygen-containing gas were supplied from the top. The upper part of the catalyst layer was filled with quartz sand as a preheating layer. The reaction temperature was measured by inserting a quartz tube containing a thermocouple into the catalyst layer. Raw material N
- Monosubstituted formamide was preheated by a preheater and introduced into the reaction tube in the form of a gas or a hot liquid. Identification and quantification of the products were carried out using gas chromatography on the gaseous substance at the outlet of the reaction tube, and gas chromatography on the liquid substance obtained by absorbing the reaction product in 1-bromonaphthalene. . Example 1 Using 2 g of a catalyst made of powdered MoO ₃ molded into a tablet, a raw material gas consisting of a molar ratio of N-n-butylformamide:oxygen:nitrogen = 1:2:20 was applied to the catalyst for SV = 3000 hours. It was introduced at a space velocity of ^-1 .
As a result of the reaction at a reaction temperature of 430°C, the conversion rate of N-n-butylformamide was 87%, the yield of n-valeronitrile was 73%, and the selectivity was 84%. 4% n-butyl isocyanate as a by-product;
n-Butyronitrile was obtained with a yield of 8%. Table 1 shows the yield and selectivity of n-valeronitrile when the reaction temperature was changed.

[Table] Example 2 A reaction was carried out under the same conditions as in Example 1 using 3 g of a catalyst prepared by molding powdered WO ₃ into tablets. When the reaction temperature was 370°C, the yield of n-valeronitrile was 10% and the selectivity was 90%. 470℃
In this case, the yield of n-valeronitrile was 48%.
The selection rate was 91%. Example 3 Using 3 g of silica gel balls heat-treated in air at 800°C for 1 hour as a catalyst, a reaction of raw material gases with a molar ratio of formanilide:oxygen:nitrogen = 1:1:40 was carried out at SV = 4000 hr ^-1. Summer. The yield of benzonitrile at 400°C was 52% and the selectivity was 80%. Example 4 A reaction of N-cyclohexylformamide was carried out using a mixture of powdered V ₂ O ₅ (1 g) and quartz sand (3 g) as a catalyst. The composition of the raw material gas is N-cyclohexylformamide;:oxygen:
Nitrogen = 2:1:20, residence time in catalyst layer is approximately 1
It was hot in seconds. The conversion of N-cyclohexylformamide at 400°C was 58%, the yield of cyclohexanonitrile was 33%, and the selectivity was 57%. Example 5 Using the same catalyst as in Example 2, a reaction of N,N'-hexamethylene diformamide was carried out.
N,N'-hexamethylene diformamide heated to 150 DEG C. was introduced into the reactor at a rate of 2 g/hr. The reaction system is maintained at a reduced pressure of approximately 100 mmHg, the amount of oxygen introduced is 0.6/hr, and the reaction temperature is 420 °C.
It was warm at ℃. The yield of suberonitrile was 35% and the selectivity was 51%. Example 6 A reaction of N-benzylformamide was carried out under the same conditions as in Example 1 using a catalyst prepared by tabletting a mixed powder consisting of equimolar moles of MoO ₃ and WO ₃ . The yield of phenylacetonitrile at 450℃ is
62%, and the selection rate was 70%. Example 7 Silica gel (2 g) heat treated at 900°C for 1 hour
The reaction of N-hexylformamide was carried out under the same conditions as in Example 3 using a mixture of powdered MoO ₃ (1 g) as a catalyst. The yield of heptanonitrile at 420°C was 68% and the selectivity was 82%. Examples 8 to 12 Table 2 shows the results of reactions of N-n-butylformamide using various catalysts under the same conditions as in Example 1. The composition ratio of the mixed catalyst indicates a molar ratio.

【table】

【table】

Claims (1)

[Claims] 1. N-monosubstituted formamide in the presence of a catalyst consisting of one or more selected from oxides of group metals and silica gel of the periodic table and an oxygen-containing gas. A method for producing nitriles from formamide, characterized in that the treatment is carried out at a temperature in the range 300-600°C. 2. The method according to claim 1, wherein the catalyst is molybdenum oxide. 3. The method according to claim 1, wherein the catalyst is tungsten oxide. 4. The method according to claim 1, wherein the catalyst is vanadium oxide. 5. The method according to claim 1, wherein the catalyst is silica gel heat-treated in air at 600 to 1000°C.