DE714311C - Process for the production of low molecular weight N-alkylated fatty acid amides - Google Patents

Description

Process for the preparation of low molecular weight N-alkylated fatty acid amides It has been found that low molecular weight 1 \ r-alkylated in a very advantageous manner Fatty acid amides can be obtained by using esters of low molecular weight fatty acids and low molecular weight alcohols in part of a column with low molecular weight Converts primary or secondary alkylenes containing alkyl radicals continuously, the reaction mixture in another part of the same column to one temperature brings, in which the amide formed is liquid, the split off alcohol and more existing fractions of the .lusgangsstoffe lower boiling than the amide in vapor form are, and the so separated vapor and liquid components through corresponding lines discharged from the column. One can with ordinary or also work with slightly increased or decreased pressure. Can be very beneficial the dimethylformamide is produced in this way from methylformate and dimethylamine. In addition to methyl formate and dimethylamine come on the one hand z. B. also ethyl acetate, Ethyl acetate or Äthvlformiat, on the other hand, for. B. monoinethyl, monoethyl or Diethylamine as starting materials into consideration.

There is an apparatus suitable for carrying out the method the enclosed drawing again. Their mode of action should be based on the example of dimethylformamide formation explained from methyl formate and dimethyl laminate «: earth.

The device consists of a long, vertical tube, the diameter of which is z. B. behaves like z, 5: ioo. Gaseous dimethylamine is introduced into the tube at the top through line 4 and liquid methyl formate through line B. In the middle of the tube at c ' the methanol formed is distilled off by a subsequent cooler, which may be contaminated with a little dimethylforinamide, while at the lower end at D the dimethylforinamide is technically pure and already immediately usable in liquid form for many applications «-Can earth.

I in the upper part E of the column, which is suitably filled with Raschig rings is one of the l 'implementation participants on the way through this part of the device to achieve the most complete implementation possible in thorough contact with each other To bring, the conversion of the ester takes place finitely your amine. The radiator jacket F serves to dissipate excess heat of conversion. If the implementation participants not, as in the present case, dimethylformamide formation without external heat input act on each other, steam can also be blown in through the jacket F in order to initiate or maintain the unisposition by heating.

The middle part of the column serves to separate the methanol formed from the reaction mixture. At the upper end of this middle part there is a lateral discharge roller C for methanol. It is generally sufficient if this part of the device is also filled with Raschig rings. More effective, however, is an arrangement that allows the Uinsetzuligsgemiscli from the PZaum T under M heat exchange with the exhausting methanol vapors to be transferred into the Zauin I_.

Such an advantageous embodiment is shown in the accompanying drawing. Here is the conversion mixture that z. B. has a temperature of 33 to 6o @ ', in the middle part H of the pipe, which is narrowed by the displacer G , filled into the lower part of the device, the bonded zone I_. In I_ the mixture is heated to above the boiling point of the methanol. and the vapors rise through the outer ring zone of the pipe T. The reflux rate can be adjusted with the aid of the condenser k so that the methanol passing over is largely freed from dimethyliormamide.

One advantage of this arrangement is that the reaction liquid flowing down in the cavity H causes the methanol vapors rising in I to be cooled and thus supports the action of the outer oil filter h. At the same time, this ensures a particularly good "separation of the @letliaitol-dimethylforniamide mixture in room I. The reaction mixture which is up to 60 = warm, warms up as it passes through H, to close to the boiling point of the metha- nols,: o (measure to be made in the heating rate I_ Noise heating is only slight. In the As a result, the coolant becomes too slow introduced above in order to stt-onigedanken acting hühlunzu el-- are sufficient. In the lower part I_ of the column this will be Resettable; emic to a temperature between your boiling point of the 'methanol (63 ° i and of diinethylformalnide (153 = ) rwarnit. For this purpose the with Raschig ring-filled space I_, e.g. E. finite Water vapor, which is generated by the -. jacket JI is filled, heated; advantageous is the ten temperature in I_ held between ioound i, # o ''. With the help of this device can slightly immediate - = 1inide of high purity obtain. In general it is multiple. the temperature at L as high as possible, im Case of Diinethylformniainids about 1- [o until i @ o = hold. To prevent dall then at C too much 1) imethylforinainide init- passes over, the implementation area can go through the cooler F are cooled so that the @ setting:; emicc @ when passing through the 13ohlratini H, for its part, has a good cooling effect kenauf the transferring, dimethylforniainid containing methanol in T. Even can be the "temperature of the coolant ini Cooler K according to the I: r- ; nrclernissen set «-erden. Aufler through the 1M @ ti. @ - described above you can take the .lrlieitsl> editi, -ttiigrii also through; "suitable dimension of the regulate individual parts of the device. At- for example, an extension of the pipe part I. and or or of the middle part T and H for a better separation of the Cm- lead settlement products. One is particularly favorable from a thermal point of view Arrangement in which the upper part of the pipe: (Room E) is no longer available. The starting materials then directly into the hollow space above cin, if necessary after previous cooling. to immediately see their cooling effect on the ini Rauin T from rising 1methanol vapors to practice. If necessary, the Cooler K can be dispensed with. On your way 1I heats the starting materials. until implementation occurs. With -nough Protection against heat radiation is insufficient occurring - conversion heat from, uni that evaporation of the resulting lletli.tnol. so that the heat required for this is not included in leads to being!) smokes. The implementation is expediently so -e- that one leads. slight excess of 1 -, increasing is not available. This avoids dafc the volatile amine in the conversion substances at C and D as impurities appears. The L herscliulan ester evaporates either already in space E or in cavity H and, if the arrangement shown in the drawing or a similar arrangement has been selected, it returns to E. `The alcohol obtained at C can, if necessary after distillation, be used as a solvent or converted into ester in a known manner and used again for the process.

It has already been proposed to produce double-methylated fatty acid alnides on nitrogen by passing a stream of air laden with dimethylamine through heated fatty acids in an intermittent manner, the water formed being distilled off. In this case, for example, up to 73 % of theoretical diinethylamide was obtained from formic acid, which had to be distilled for purification, in particular to separate off the unreacted fatty acid. In contrast, the new process allows the continuous production of low molecular weight alkylated fatty acid amides in a single operation with approximately the calculated yield in almost pure form, diluted at most by small amounts of easily separable alcohols. Example In a device filled with finite Raschig rings, the length of which is cm and the internal width of 25 mm and which essentially corresponds to the one described above, in which, however, the spaces H and I are not separated and a displacement body G is not present is, 54. g of methyl formate and .1o.5 g of dimethylamine are reacted per hour. The temperature in the approximately .40 cm long upper part of the column in which the reaction takes place (corresponding to E) is not influenced from the outside; the middle, about 17 cm long part below C is cooled with tap water, the lower part, about 33 cm long, is heated electrically to about 0 °. Gr ° lo of the expected amount of dimethylformamide are collected together with a little methanol at the lower end of the column. A further 5 ° 10 of the calculated yield distill off together with the methanol at the side: "#, filler C in the middle part of the cosonne. The methyl formate has therefore almost completely reacted with the dimethylamine to form dimethylformamide.

When using one of the drawings explained above exactly corresponding Device an at least as complete implementation is achieved and also an almost complete separation of the methanol and dimethylformamide, whereby the methanol leaves the device at C, the dimethylformamide at D_.

Claims (1)

PATENT CLAIMS: i. Process for the production of fully low molecular weight \ T-alkylated fatty acid amides, in particular of dimethylformamide, characterized in that that one esters of low molecular weight fatty acids and low molecular weight alcohols in a column with low molecular weight alkyl radicals containing primary or secondary alkylamines continuously and the reaction mixture in one brings other part of the same column to a temperature at which that formed Amide is liquid, the split off alcohol and remaining alcohol is lower than that Amide-boiling fractions of the starting materials are, however, vaporous, and so from one another separate vapor and liquid components through appropriate lines the column discharges. z. Embodiment of the method according to claim r, characterized characterized in that the conversion mixture formed in the conversion space by a connected to the column vessel part is passed, the wall of which a heat exchange mediated with the vaporous fractions to be fractionated. 3. Execution form of the method according to claim Z and a, characterized in that the starting materials can not be implemented in a special part of the column, but it immediately, if necessary after cooling, introduced into the part of the column which is in heat exchange with the distilled off portions.