DE1618884B1 - Process for the preparation of 3-methyl mercaptoproionaldehyde - Google Patents

Description

i 618 884

1 2

The invention relates to a process for the preparation of ethyl mercaptan used in large excess of 3-methyl mercaptopropionaldehyde, which was used below. - ■ "-.-.
referred to as M-aldehyde, in high yield. This further had to be in the technical continuous connection is a valuable intermediate product for the lent process the reaction under pressure by the production of methionine. 5, while in the case of paragraph-wise

There are various processes for the preparation of driving the reaction at atmospheric pressure er-M-aldehyde known, for. B, a batch procedure, followed. This is presumably due to the fact that a catalyst results in a liquid mixture. supply that methyl mercaptan boils at 6 ° C and given from acrolein or methyl mercaptan, it is therefore easily evaporated. The formation of one and then methyl mercaptan or acrolein as a liquid io heterogeneous gas-liquid phase in a thin fluid or gas directly into this liquid under the reaction tube was fed in as a disadvantage for the thorough cooling and stirring (YgL J .. Am, borrowed Contact of the reaction participants as well as _: for the Chem. Soc, Vol. 70 [1948], p. 1450). The implementation, considered to be effective removal of the heat of reaction, is exothermic at about 14 kcal / mole. Both the subject matter of the invention is a process for the acrolein used and the M-aldehyde formed and the production of 3-methylmercaptopropionaldehyde are thermally unstable. In particular, acrolein is easily subject to polymerization due to the reaction of acrolein and methyl mercaptan. In the reaction in the presence of a catalyst in the liquid phase of acrolein with methyl mercaptan, one with heat dissipation in two stages, which is characterized by a device for regulating the reaction temperature, is required in the first stage. In order to keep the reaction temperature in this 20 thylmercaptan with 3-methylmercaptopropionaldehyde process below a certain value in a molar ratio of 1 to at least 1 at 10 to, the reaction system was cooled or the 90 ⁰ C converted until the heat development practically ended the rate of addition of the starting compounds and controls the reaction obtained in step one. However, since the implementation of a product initially converts with acrolein in the second stage,
particularly vigorous heat development is accompanied, 25 Iil the first stage of the representation according to the invention on local heat accumulations, whereby secondary reactions methyl mercaptan with M-aldehyde are promoted. The procedure has set. In this case, the hemithioacetal is believed to have the further disadvantage that it is poorly reproducible """" or thioacetal. The amount of heat generated in this case is about two thirds (9 kcal /

In order to overcome the aforementioned difficulties- 30 mol), the amount of heat in the case of direct implementation of

^ den, a process was developed in which the re-methyl mercaptan with acrolein. That is why it is shaped

Participants with solvents such as acetals make cooling easier.

or dioxanes, can be diluted to localize. In the first stage, no catalyst is required.

To moderate heat generation in the reaction system The reactants are usually in one

(see French patent specification 976 673). The mixing tank is thoroughly mixed together,

As a result, driving requires the recovery of the M-aldehyde which is a high-boiling compound and

Solvent and is therefore technically not available, as a result, it is put into the mixing tank in liquid form

partaking. fed in. Methyl mercaptan comes in either form

From US Pat. No. 2,676,190, a compound is supplied to a liquid or as a gas. Preferably

drive known, at which 67 to 90% of the theoretical 40 is · the methyl mercaptan in the M-aldehyde thoroughly

Amount of acrolein first dispersed to the methyl mercaptan and effectively removing the heat generated,

be added and then the rest of the acrolein when using methyl mercaptan in liquid

is added quickly. After this process the mold is vaporized some of the methyl mercaptan,

technical production of M-aldehyde in the way and consequently the local heat development

carried out that a reaction liquid are distributed under Verr 45 development. Preferably, however, that

Turning a long tubular reaction vessel, methyl mercaptan is fed as a gas as it is in this

circulated and a liquid mixture from mold is even more easily distributed in the M-aldehyde.

Methyl mercaptan, catalyst and acrolein separated Of course, mechanical stirring is very effective.

and partly under pressure by one or more sam. The reaction vessel can be cooled with a

Openings is fed into this recycle stream. .50 cooling jacket or a cooling coil.

In the process, the heat of reaction is through The reaction liquid can also be through a

Cooling the reaction vessel with water removed. Lead the heat exchanger in the circuit.

However, in order to effectively dissipate the heat of reaction, - In the implementation described above,

The reaction vessel must have a relatively narrow volume of the M-aldehyde in an amount of at least 1 mol

and the amount of the circulated liquid is used per mole of methyl mereaptane. With larger

ability to be made larger. Thus, the process amount of M-aldehyde will regulate the temperature

not only operational and economic disadvantages due to the diluting effect of the M-aldehyde

because the energy required for circulation is lighter. However, if the amount is excessive,

is large, but also shows the disadvantage that there may be work difficulties,

the inside of the reaction vessel easily through poly- ° Usually 1.5 to 200 moles, preferably

mere becomes clogged. 10 to 100 moles, M-aldehyde per mole of methyl mercaptan

As stated above, is used in the usual.

A process for preparing M-aldehyde, the Re- The temperature in this reaction in the first gelung the reaction temperature is only by physical level 10 to 90 ° C, preferably 40 to 8O ⁰ C. causes Kara measures. Therefore, 65 cases turned out to be implementation at lower rates. Temperatures when the control is unsatisfactory and the ^{output 10 0} G is carried out, a cooling medium is necessary. Yield of M-aldehyde was usually 92 to 95% manoeuvrable to cool the reaction mixture. In and not more than about 98%> even if metal higher reaction temperature can be used as 90 ⁰ C, the

3 4

Only a small amount of methyl mercaptan dissolves the acrolein either directly in the liquid reaction and the M-aldehyde decomposes. product are fed under cooling or the

The reaction is preferably carried out at atmospheric reaction liquid and the acrolein can be condensed, but it can also be carried out continuously at a higher pressure in another reaction vessel with stirring. After the invention 5 and cooling are initiated. Finally, the method according to the methyl mercaptan is (Kp initiated. About 150 ⁰ C at 760 mm action tube and with each other under external Hg) in both components in a tubular Reflüssigem M-aldehyde and reacted. Therefore not only the cooling should be implemented. The partial reaction pressure of the methyl mercaptan above the reaction temperature during the reaction can be low, but also the io formed can be controlled by the fact that the components pre-heat is low and easily removable. It is therefore refrigerated and then mixed together and does not require a tubular reaction vessel and set so that the temperature rise below the reaction can be successfully maintained at half-atmospheric levels. When printing is performed. part of the

In the drawings, F i g. 1 the partial pressure of 15 th M-aldehyde is returned to the reaction zone of the first of the methyl mercaptan above the methyl mercaptan M stage, it is possible to use the invented aldehyde reaction liquid. The curve (1) shows the method according to the invention to be carried out continuously.
Relationship between the concentration of the methyl mercaptan added in the second reaction stage in the Methyhnercaptan-M- reversible catalysts are mercury-methyl-aldehyde reaction liquid and the temperature 20 mercaptid, copperQDQ-acetate, organic peroxides, or this liquid, if the Partial pressure of methyl ganic bases, mixtures of organic bases and mercaptans is 200 mm Hg. The curve (2) shows organic acids and ion exchange resins. Katad this relationship, if the partial pressure practically lysator and acrolein can either together amounts to 0 mm Hg. or fed separately. Usually it will

The curve (2) can be expressed approximately by the following equation 25 acrolein in approximately the same amount as methyl mercaptan

are reproduced: equivalent amount used, but it can also

in a slightly smaller or slightly larger amount

γ ς ο «ιη-5Λχι« -ms * _ι_ ή ix * ^ ^the equivalent amount can be used. FaUs

Ji - V »-10 t + L ₃ IZ-LV f + lVHö. Acrolein in an amount smaller than the equivalent

30 amount is used, diffuses the methyl mercap-

X means the molar fraction of methyl mercaptan tan in the M-aldehyde, and if the mixture is im

in the methyl mercaptan-M-aldehyde reaction liquid circuit, it is possible to introduce

acrolein in the reaction zone of the first stage

avoid. This can prevent the strong heat build-up

_{χ =} MolMethylmercaptan.eingebrachtinM aldehyde _{35 ung} i _o n the basis of the direct reaction of methyl

Total moles of M-aldehyde and methylmer- mercaptan with acrolein are avoided. If otherwise

captan, introduced into M-aldehyde, on the other hand, acrolein is used in excess,

unreacted methyl mercaptan is practically not taken up in the M-aldehyde. Since low

t is the temperature (° C) of the methyl mercaptan M-40 amounts of taken up in the M-aldehyde

Aldehyde reaction liquid. Methyl mercaptan are difficult to separate

In FIG. 1 in the area below which the application of a certain excess of acro-

Curve (2) the partial pressure of the methyl mercaptan on a lein is extremely advantageous if the cleaning

the methyl mercaptan-M-aldehyde reaction liquid takes into account. If the process is

practically 0mm Hg and the implementation can be carried out in a 45 course and the excess

open system running at atmospheric pressure the amount of acrolein is too large, the

will. first stage introduced, non-evacuated

The conversion of methyl mercaptan and M-Al- increased the amount of acrolein, which directly with methyl-

dehydration is carried out until the reaction heat- mercaptan reacts, which may result in

development is practically complete at this stage, so local overheating of the reaction system

that part of the heat of formation of M-aldehyde can determine. Therefore, the excess amount is

was released in fractions. To this preferably only 0.5 to 20 mol percent,

Purpose it is necessary to use the two reaction parts - The reaction used in the second stage

Takes usually 0.1 to 60 minutes, preferably conditions are practically the same as in the

5 to 30 minutes to bring together. 55 first stage. The implementation will either be at

The reaction product obtained is then atmospheric pressure or under excess pressure

from methyl mercaptan and M-aldehyde with acrolein in temperatures of 10 to 100 ⁰ C _5, preferably 30 to

the second stage in the presence of a catalyst 70 ⁰ C, carried out and continued until the formation

brought to implementation. The resulting product is practically terminated by M-aldehyde. The implementation

presumably the hemithioacetal or thioacetal, reaction time is 1 to 180 minutes, preferably

yeasts with acrolein to form M-aldehyde. 1 to 60 minutes.

In this reaction, only about 5 kcal / mole are produced. The M-aldehyde is formed by fractional heat of distillation, and the methyl mercaptan is obtained with lation of the reaction liquid.
M-aldehyde dilutes so that it is easier to avoid local overheating when the process in the above described. This is particularly important; if the reaction temperature is carried out in acrolein, the acrolein can be polymerized very easily and an increase in temperature can be easily regulated, and the reaction temperature in this stage is practically so far as no local overheating is obtained. The yield should be avoided as possible. In this step can then transmits at least 99% ^er d theory.

. An example of a process according to the invention. The content of M-aldehyde in the liquid was

Drive usable reaction device is determined in by gas chromatography. Fig. 2 explains. Methyl mercaptan is used as a gas ti · ■ - · -i ö

through a nozzle 9 in M-aldehyde in the tank 1 an example ^

jetted. The tank 1 is at its upper part with a 5- A 1 liter four-necked flask was provided with packed column 2, which allows a stirrer, reflux condenser, thermometer liquid • absorption of methyl mercaptan The keitseinleitungsrohr (for M-aldehyde) and gas inlet. Top of the column! is equipped with line 12 with pipe (for methyl mercaptan). In connection with the atmosphere. The reaction liquid was connected to the bottom of the flask by a pipe so that it is drawn from the bottom of the tank 1 through the line 8j ίο that the reaction liquid overflow from the pump 7, the line 5 * the heat exchanger 4. A second four-necked flask and the line 3 in the column 2 in the circuit were fed with a stirrer, thermometer, three liquids. A part of the reaction liquid from the tank 1 keitseinleitungsfohren (for the liquid from which is drawn through the line 6 on the access side of the first flask, acrolein and catalyst) and a pump to ensure that no heat 15 reflux condenser is fitted. With the bottom of the development would be caused. second piston was a tube for pulling off the

Cooling water is through line 13 in the product liquid through overflow and a pipe to Heat exchanger 4 initiated and through the lei- withdrawing the return to the first pistonl4 derived. Acrolein and a catalyst-generating liquid are connected. The two pistons are fed through the lines 11 and 10 respectively 20 were individually on-on in separate thermostat tanks Part of the reaction liquid is immersed through the pipe and connected to a line so that tunglS withdrawn so that the liquid level in the liquid is withdrawn from the bottom of the second flask Tank 1 is held at a certain height. The and fed with a pump into the first piston Implementation of methyl mercaptan and M-aldehyde could be. 359 g of M-aldehyde were each in is effected in the tank 1 and the column 2 and 25 before the first piston and the second piston heat formed therein by means of the heat design. The first flask was 294.4 g / hr. Exchanger 4 removed The reaction of acrolein with methyl mercaptan as a gas (purity 99.5 volume promoter Reaction liquid from methyl mercaptan and cent) initiated. In the second flask were M-aldehyde is carried out in line 3. 400 g / hour Acrolein (purity 95.7 percent by weight)

The examples illustrate the invention. 30 and 7.2 g / h of a catalyst (25 percent by weight

Pyridine + 75 percent by weight acetic acid) continuously

'_ ". ■; fed in part of the reaction liquid

In the case of the first piston, it was through the tube in front of the

Introducing the liquid into the second flask ab-35 drawn. It was found that practically none

A 1 liter four neck flask. was done with heat generation. The temperature in each of a stirrer, liquid inlet tube (for M-Al flasks was set at 50 - ± 2 ° C by regulating the temdehyde). Gas inlet pipe (for methyl mercaptan), maintained temperature of each thermostat container. After a thermometer and a 4-hour reaction to the atmosphere, the product liquid was fitted with a tube. 40 were withdrawn into the flask in an amount corresponding to the amount formed over a period of 388 g of M-aldehyde (purity 99.5 percent by weight) in 30 minutes. Brought it. The entire flask was immersed in ice water, 348 g of a colorless, transparent liquid and 96.5 g of methyl mercaptan (purity 99.5. The amount of M-aldehyde in the M-aldehyde is introduced with stirring. The 45 'liquid temperature is 90.4 weight percent and the out in the flask was maintained at 30 ° C. After the beginning of the recovery - based on methyl mercaptan - 99.2% of that of the introduction of methyl mercaptan, the temperature theory began. Furthermore, the material balance (amount of temperature to increase. There was no methyl mercaptan product per amount of feed) was practically 100%, and into the atmosphere released After completion of A * methyl mercaptan and acrolein were hardly enticing, the temperature of the cooling water within 50 flüchtigt despite the fact that the reaction system halbetwal5 minutes on 30 ^o was open to the atmosphere CerhöhtündderKolben-. content kept at 30 ° .G,. ,

The liquid formed was mixed with 1.7 g of a Ka example

catalyst & (25 percent by weight pyridine + 75 percent by weight acetic acid) thoroughly mixed ^ and then 55 A reaction device according to Fig. 2 with 120.0 g of acrolein (purity 96.3% by weight - a total volume of about 10 liters was added to the mixture). Built during the encore. For example, the temperature of the contents of the flask was brought into the reaction device by external 4 liters of M-aldehyde in such a way that part of the cooling was kept at a value below 40.degree. Tanks 1, the pump ?, the heat exchanger 4 and 606 g of a colorless, transparent liquid were used. The lines were filled. The pump 7 was kept in liquid. Analysis of the liquid obtained in order to circulate the liquid showed that the increase in the amount of M-aldehyde resulted. The amount of liquid circulated was 206 g and the yield based on methyl mercury was about the 20 times the amount of product captan * was 99.1% of theory. Then, if for locking liquid methyl mercaptan were equal to the methyl mercaptan with acrolein directly under 65 as a gas (purity 99.5 volume percent), a catalyst cooling the system with ice water at 0 ⁰ C vice * (25 percent by weight of pyridine is 4 * 75 weight percent, is the yield of M-aldehyde (only acetic acid) and acrolein (purity 96.0 weight? 92% of theory. Percent) in the amounts given in the table

Acrolein
(A)
(g / h) 7th methyl
mercaptan
(B)
(g / h) catalyst
(g / h) Mole
relationship
AWAY Tanlc
tempera-
door
( ⁰ C) Amount of
product
liquid
(g / 15 minutes) 8th material
balance sheet
(7o) the end
prey*)
(%) Ver
search
No. 2190
2200
1100
2200 1820
1800
900
1800 40
40
20th
40 0.995
1.011
1.011
1.011 50
50
80
50 1008
1005
500
1000 concentration
of M-aldehyde
in the product
liquid
(%) 99.7
99.5
99.0
99.0 99.0
99.2
96.9
97.5 1
2
3
4th 95.9
95.8
95.0
95.6

*) The yield in experiment 1 is based on acrolein and the yields in experiments 2 to 4 on methyl mercaptan.

introduced through lines 9, 10 and 11, respectively. A part the reaction liquid was withdrawn from the tank 1 through the pipe 6 to determine whether the heat generation ended. The reaction product was withdrawn through line 15 so that the The liquid level of the tank was kept at a certain level. Cooling water was through the Heat exchanger performed in order to keep the reaction temperature constant, while at the same time a certain Subcooling of the circulating reaction liquid took place: the remaining heat of reaction, which arose in the line 3, was due to heat radiation destroyed. The reaction temperature was about 52 ° C in the tank and about 50 ° C in line 3. After 8 hours of reaction, a sample corresponding to that in a period of time decreased amount formed by 15 minutes and subjected to a calculation of the material balance and the analysis of M-aldehyde. The analytical procedure was the same as in Example 1.

The reactions of experiments 1 to 3 were carried out using column 2. the Implementation of experiment 4 was carried out with an empty column.

Claims (3)

Patent claims: 1. Process for the preparation of 3-methyl mercaptopropionaldehyde by reacting acrolein with methyl mercaptan in the presence of a catalyst in the liquid phase with heat dissipation in two stages, characterized in that methyl mercaptan is used in the first stage with 3-methylmercaptopropionaldehyde in a molar ratio of 1 to at least 1 at 10 to 90 ° C converts until the heat development has practically ended, and that obtained in stage one Reacts reaction product in the second stage with acrolein. 2. The method according to claim 1, characterized in that the reaction in the second Stage carried out at 10 to 100 ° C. 3. The method according to claim 1 and 2, characterized in that the reaction in the first Stage with 1.5 to 200 moles of 3-methyl mercaptopropionaldehyde per mole of methyl mercaptan-leads. 1 sheet of drawings COPY 109 538/382