JPS5877845A - Preparation of acrylic acid ester or methacrylic acid ester - Google Patents

Abstract

PURPOSE:To prepare the titled compound in high yield, reducing the amount of by-products, and eliminating the recovering process of the unreacted alcohol, by adjusting the molar ratio of acrylic acid or methancrylic acid to the alcohol within a specific range, and directly esterifying under specific conditions. CONSTITUTION:The molar ratio of acrylic acid or methacrylic acid[hereinafter called as (meth)acrylic acid) to a 1-3C lower aliphatic alcohol is adjusted to 1 to 1.0-2.0, and the mixture is esterified in the presence of an acidic catalyst (e.g. H2SO4, sulfonic acid, etc.) at 60-100 deg.C to obtain an acrylic acid ester or methacrylic acid ester[hereinafter called as (meth)acrylic acid ester]. In the above process, the (meth)acrylic acid ester is fed from the outside of the system to the distillation column to obtain a distillate free from (meth)acrylic acid and composed of the objective compound, water produced by the esterification reaction, and the unreacted alcohol. The bottom liquid of the distillation column essentially free from the produced water is recycled to the esterification reaction. Since the amount of the unreacted alcohol is very small, it is not necessary to use the recovery process, and the whole process can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acrylic esters or methacrylic esters. Specifically, the present invention involves a direct esterification reaction of acrylic acid or methacrylic acid [hereinafter referred to as (meth)acrylic acid] and a lower aliphatic alcohol having 1 to 3 carbon atoms at a low molar ratio in the presence of an acidic catalyst. Seshime (
The present invention relates to a method for continuously producing meth)acrylic acid ester.

(meth)acrylic acid and meth] tool, ethanol-Fiz,
It is well known that the corresponding ester can be converted by an esterification reaction with a lower aliphatic alcohol such as isopropanol, and this reaction can be an equilibrium reaction. It is also well known that alcohol, (meth)acrylic acid, and water produced by the reaction coexist in the reaction of hydrogen. In order to separate the (meth)acrylic ester and produced water from such a reaction product, distillation has traditionally been used.

L, the affinity between water and (meth)acrylic acid is strong and when the produced water is distilled off, there is a tendency that (meth)acrylic M is inevitably distilled out along with the water. . Even if the number of distillation stages and the reflux ratio are increased, the waste cannot be separated to a considerable degree, making the (meth)acrylic acid ester "J" process complicated and generating a large amount of return water. It shows skin defects such as.

Furthermore, if the molar ratio of alcohol to (meth)acrylic acid supplied to the ester-rich reaction is lowered, the amount of (meth)acrylic acid entrained and distilled out together with the produced water tends to increase. Generally, it is carried out within the maximum range of ~5, and costs are unavoidable due to recovery of unreacted alcohol, increase in reactor capacity, increase in utilities, etc.

On the other hand, in order to suppress the above-mentioned affinity between water and (meth)acrylic>2, an S gonorrhizal agent having a higher affinity with water of 17 f is added to distill the reaction product water from the reaction product 1 by azeotropy. It is also known that These entrainers include benzene, toluene, xylene, and the like. However, the operation of separating these co-fillers and (meth)acrylic acid esters is not easy, and requires complicated preparations including recovery, which is extremely disadvantageous economically.

The present invention takes into account the shortcomings of the prior art and provides a process for continuously producing (meth)acrylic quasi-ester from (meth)acrylic RV and a low-grade alcohol. In particular, since the molar ratio of (meth)acrylic acid and aliphatic alcohol supplied to the reaction yarn is in a very low range of 1:1 to 2, the alcohol recovery process is very difficult. At the same time, utilities such as l-steam are greatly reduced, and the removal of (meth)acrylic acid and alcohol is extremely high compared to conventional methods. It provides an ester-producing process.

That is, the present invention is specified as follows.

(1) Acrylic acid or methacrylic acid with 1 or more carbon atoms
When producing acrylic ester or methacrylic ester by esterification reaction with the lower aliphatic alcohol of No. 3 in the presence of an acidic catalyst, molar ratio fl of acrylic acid or methacrylic alcohol to be supplied as a raw material.
: range of 1.0 to 2.0, and ester reaction to 60 to 2.0.
Esterification reaction mixture performed and observed at a temperature of Zoo°C.

An acrylic ester or methacrylic ester that is substantially free of acrylic acid or methacrylic acid by distilling a substance and then supplying fresh acrylic ester or methacrylic ester to the distillation column from outside the thread;
An acrylic acid process characterized by depleting the distillate consisting of esterification reaction product water and unreacted alcohol, and circulating the distillation column liquid from which the product water has been substantially removed to the esterification reaction.゛Production method of ester or methacrylic acid ester.

The present invention will be explained in more detail below.

The raw materials (meth)acrylic acid and lower aliphatic are placed in a reaction tank that contains an acidic Nistellite catalyst and is maintained at a constant temperature. Since the Esterich reaction is an equilibrium reaction, the reaction product contains unreacted alcohol and (meth)acrylic acid. Then, in the distillation column, the target product (meth)acrylic'lt ester and the produced water must be distilled out, while unreacted (meth)acrylic acid remains in the bottom liquid (Thl+) and is esterified. It will be supplied for reaction.

In order for this distillation to be carried out as desired, it is necessary to newly feed (meth)acrylic acid ester of the same type as the target product from the top of the column, and to avoid containing substantially unreacted (meth)acrylic acid. It has been found that it is advantageous to distill off the acrylic ester, produced water, and trace amounts of unreacted acycol.

Mainly unreacted (meth)acrylic acid, a small amount of water, and (meth)acrylic acid ester remain on the tank liquid side, and are recycled to the ester reaction tank.

Really not B1. rC,: It is preferable that the circulation of the can liquid from (meth)ac-11acrylic acid be at least IPII class with respect to the newly supplied raw material. When f + 1, the mixed raw material Ukang supplied to the ester reactor is (meta) 7
This is because it has been found that the formation of impurities, mainly alkoxy compounds, in the ester reaction is greatly reduced by forming a (meta) compound. It is unfortunate that the yields are similar for both acrylic acid and alcohol.

That is, the present inventors used lli[! Conventionally, the yield from (meth)acrylic acid is 91 to 9.
Unfortunately, the yield from alcohol was 94-97%, but the former yield was 96-99%, and the latter was 97-99.5%, which is higher than conventional KfX. Moreover, along with this operation, a new supply (
Obtaining the distillate of the distillation column so as to substantially match the balance between meth)acrylic acid and alcohol, that is, when the supplied (meth)acrylic acid is substantially 100%
In combination with an operation in which an amount of (meth)acrylic ester corresponding to the amount transferred to % ester and the corresponding produced water are taken out as a distillate bath, it is possible to produce an extremely smooth external (meth)acrylic ester. The E-building process is carried out continuously.

A distillate containing the (meth)acrylic acid ester and produced water obtained from the distillation column is separated into two phases, and the aqueous phase contains the alcohol and (meth)acrylic acid varnish contained therein. It is sent to the 1E11 recovery step. Also, (meth)acrylic acid ester is obtained by separating alcohol and water from the oil phase. The amount of reaction alcohol is extremely small, and there is no longer a need for extraction paste to recover the alcohol as in the past, which is a major advantage for Froseth.

On the other hand, (meth)acrylic acid is actually retained in the bottom liquid of the distillation column, and at least in terms of weight compared to the (meth)acrylic acid and alcohol fed to the ester reactor. It is preferable to circulate and supply the amount by 1.0 times. Increasing the number of circulations does not have much effect on the resistance, but there is no point in increasing the number of attacks, and there is no need to increase the number of attacks by more than seven times. and (for K acrylic butymethyl ester, 1-ii) 1. o to 2.0 times is preferable, and when the purpose is methyl methacrylate, ethyl (meth)acrylic acid, or inpropyl ester, it is 2.0 to 5.0 o.
It is better to double it. New supply of Esther
The molar ratio of meth)acrylic acid and alcohol is 】:1.0
~2.01 Fil is preferably in the range of 1 to 1.5.

Examples of the acidic catalyst used in the present invention include liquid catalysts such as para-toluenesulfonic acid, sulfuric acid, sulfonic acid, hydrochloric acid, etc., and solid catalysts such as strongly monovalent ion exchange resins. There is an acid catalyst in step 11. The ester reaction usually occurs under the presence of an inhibitor. 9.1
Hydroquinone, hydroquinone methyl ether, phenothiazine, etc. are generally recommended as inhibitors for (meth)acrylic acid.
1 liter / % flow force r / Ester reaction reaction + 414i, 60-100°C, preferably L < is 60-9
The temperature is 0°C, and the pressure is sufficient to maintain the reaction rate in the liquid phase.
]11 No pressure [slight pressure (0.5~2.0~/Bei 2
It is better to omit c). During the residence of the reactor in the reaction tank, N
It takes about 0.5 to 10 hours, but even if it takes longer, it's still economical! It is not.

Next, Example 4A of the method of the present invention is prepared from 2.1 nic; in the middle, (meth)acrylic acid is supplied to % 1, real alcohol is supplied to % 1, and the unreacted ( The canned liquid of the steamer 'Go' 5 containing a large amount of meth)acrylic acid is circulated through the gas pipe 6, and the unreacted (meth) and acrylic acid are The liquid from the distillation column that declares +1 is combined with the liquid from the distillation column, and is transferred to reaction tank 3 containing an acidic catalyst. Unrebelled.

The liquid from the distillation column containing (meth)acrylic acid is No-Onna L.
In order to remove the high-boiling point compounds, 1 compounds, etc. generated in r1, some or all of them are filtered into a filter, if necessary, and the light components that are distilled are added to the circulating fluid. Next, 'jy,
5. , it is preferable to prevent the vcB material in the system from accumulating.

At Pj Lr, /1fJ3, (meth)acrylic acid and alcohol are esterified at 1 near equilibrium, and the reaction mixture consisting of (meth)acrylic ester, water, unreacted alcohol, and (meth)acrylic acid is passed through conduit 4. It is supplied to the distillation column 5. # In distillation tower 5, (meth)acrylic acid ester, water produced, and unreacted alcohol are distilled out in an amount that is practically equal to the theoretical mass balance between (meth)acrylic acid and alcohol. In this process, (meth)7% ester of IJ-h is supplied through conduit 7 to obtain a distillate substantially free of (meth)acrylic acid. At this time, the (meth)acrylic mulberry ester (meth) supplied from the conduit 7 (11, ) In the case of ethyl and isopropyl esters of acrylic be, it is necessary to supply them in a ratio of 8 to 13.57-11. It's okay to go along with it, but economically speaking, Yuzu, which has a rating of 7, is better.

The (meth)acrylic acid ester of the raw hV valve is substantially equal to the 5 to 4 mixture of (meth)acrylic acid and alcohol produced A1, unreacted alcohol and supplied in conduit 7. The (meth)acrylic acid ester of No. 4 is sent via conduit 8 to oil/water 1iA+19 &c.

The (meth)acrylic ester phase separated in the oil-water separation tank 9 is fed to the IPI-water separation tower 12V via a conduit, but it may also be passed through an extraction tower if necessary.

In the shaft separation column 12, the (meth)acrylic ester from which the alcohol, water, and impurities have been separated is taken out through a conduit 17 from the bottom of the tower and sent to the tank 1. It is circulated to the distillation column via the iJ conductor 7, and is fed to the rectification column 19 after gauging the outer sludge HL...18.

It is passed through the light fractionating column 12, and is sent to distillate 84-k (meth)acrylic 1 ester, alcohol, and oil/water 1['l 14 through the OHA conduit 13, and the (meth)acrylic acid ester phase is sent to the top of the column. Guide II! Hit r15 and you will be sent to Kuizaka.

Oil/Water Separation [The aqueous phase separated in 9 and 14 is taken out via conduits 11 and 16 and sent to an alcohol recovery column if necessary, where alcohol and (meth)acrylic acid ester are recovered and sent back to the reaction tank via conduit 2. Supplied. The (meth)acrylic acid ester produced privately in the Q column 19 is taken out as a product through the conduit 20.2 and is led from the bottom of the column to 1 ton.
The bottom liquid is taken out via 22.

Hereinafter, the method of this invention will be explained in more detail with reference to examples, but the invention is of course not limited to the following examples.

Example (i mol), methyl alcohol containing 0.2 parts by weight of water and 8.3] iti parts of acrylic eye/methyl 2.91
% (83.1 mol), hydroquinone corresponding to 0.05 parts by weight and 1 p4 of acrylic acid in the added solution was added, and this and the distillation column liquid were mixed with each other at 11.0 m/hour. It was mixed with 87Kf and supplied. The mixed solution thus supplied to this reaction tank contained 9.13i of methyl acrylate.
t%, methyl alcohol 14.2] m warehouse clerk, acrylic alcohol 52.7N deafness and water, by-products, etc. za, 5iir+
Due to this situation, the 6 reactors were placed in a hot water bath at 19.78 p.m., and the temperature inside the reactor was maintained at 80°C. 99% of the acrylic acid in the reaction stock solution newly supplied in the Kommel reaction tank was converted into methyl acrylate.

The reaction product taken out from the reaction tank is sent to a distillation column,
Methyl acrylate containing 0.021 g of hydroquinone was fed from the top of the column at a rate of 9.77 kg per hour and distilled at normal pressure. At this time, the tower top temperature was 69℃, and the pot temperature was 10℃.
The temperature was 2°C. In this way, every hour 17
．． 53 kg of distillate was obtained, the composition of which was 90.5% by weight of methyl acrylate, 2.5% by weight of methyl alcohol.
, 7.0 g of water, and acrylic I! #Fin, o
005 or less, the distillation column liquid was extracted at 12.02' every hour, and 2.4 Kf of this was sent to the thin film evaporator to collect high boiling point substances and 1 compound. After removing such substances, the mixture was mixed with 9.62~ of the hem and circulated to the reaction tank.

The distillate of $1 from the distillation column was sent to an oil/water supply tank and separated into an acrylic methyl chloride and an aqueous phase. Methyl acrylate phase iJ &
Methyl alcohol and water were separated in the Kabubu tower and sent to the rectification tower to obtain methyl acrylate. On the other hand, the aqueous phase is
The mixture was mixed with methyl alcohol and water that had been separated in the shank separation column, sent to an alcohol recovery column, where most of the water was removed, and then circulated to the reaction tank. As a result, the yield of methyl acrylate was 97.84 with respect to the acrylic acid used, and the yield of methyl alcohol was 99.

$h4/! l 2 Example 1 and 5.0~(
69.4 mol) and 7.61 mol of water and 4.8 IF
Ethyl alcohol containing ethyl acrylate 4.38
In the reaction stock solution consisting of K4 (s a, 3 mol), hydroquinone corresponding to 0.05 iJii was added to the acrylic acid being removed, and this and the acrylic acid from the distillation column liquid were added to the reaction stock solution, 23.45~ were mixed together and the strongly acidic cationic resin 707 was supplied to a reaction tank maintained at 80°C.

Thus, the canned mixture supplied to the reaction tank contained 16.73 ke of ethyl acrylate and 13.0771 ke of ethyl alcohol.
Section i, Acrylic It 42.3 >ir'Iy,
And water, by-products, etc. were 27.9 offshore, and it was 9 at 32.83 per hour. In this reaction tank, '114
98% of the acrylic acid in the reaction stock solution supplied was transferred to ethyl acrylate.

The reaction product φ7. taken out from the reaction tank was sent to a distillation column, and from column 1, ethyl acrylate containing 0.02% of hydroquinone was added at a rate of 2.72 to 2.72% per hour, and the mixture was distilled at normal pressure. At this time, the tower] M temperature was 79°C, and the pot temperature was 110°C.
1.93 kg of distillate was collected, the composition of which was 81.6 ethyl acrylate, 5-4 N' ethyl alcohol.
*' qb s water 13. O'i, ff4 [Ruri, acrylic acid ke o, ooosl trigram/section and below. on the other hand,
'# The bottom liquid from the distillation column is extracted every 23.62 Kl, and 2.36 Kl of this is sent to a thin film evaporator to remove high-temperature substances, 1 compound, etc., and then the remaining 21.6 Kl is removed. The mixture was mixed with 26 breasts and circulated to the reaction tank.

#The distillate from the distillation tower was drained and sent to an oil-water separation tank, where it was separated into an acrylic quasi-ethyl phase and an aqueous phase. Ethyl alcohol and water were separated from the ethyl acrylate phase in a light fraction separation column, and the mixture was sent to a distillation column to obtain ethyl acrylate.

- The aqueous phase was mixed with ethyl alcohol and water for splitting in the light fraction separation tower, sent to the alcohol recovery tower to remove most of the water, and circulated to the reaction tank. As a result, the weir height of ethyl acrylate was 97.5 points higher than that of the acrylic acid used, and the lo1 yield of ethyl alcohol was 98.6 points higher.

Example 3 5.0 kg of methacrylic acid per hour in the same manner as Foreign matter 11
(58,] mol) and 2.2 parts of methyl alcohol containing 0.4 parts of water and 1.3 parts of methyl methacrylate.
Hydroquinone corresponding to 0.051 = 1.0% of the methacrylic acid in the mackerel liquid was added to the reaction liquid consisting of 7 rl (69.6 mol), and this and the distillation column liquid, 75
At 36.35 hrs., the strong cation exchanger I fat 901 was supplied to a reaction tank maintained at 280° C. at 36.35 hrs.

After smelt, the mixed solution supplied to the reaction tank contains methyl methacrylate 4a, 8ii [[, methyl alcohol 6.8 units, methacrylic sugar 43.6 Jyutoki water, by-products, etc.5. It consisted of 71 mass regrets and was 9 at 43.62 per hour.

In this reaction tank, 99 pieces of methacrylic horse mackerel in the newly softened reaction mixture were transferred to methyl methacrylate.

The reaction product taken out from the reaction tank is sent to a distillation column.
Methyl methacrylate containing 0.02i347% of hydroquinone was introduced from the top of the column at a rate of 3.57 kg per hour and distilled at n pressure. The increased temperature at this time is 85℃, and the pot temperature is 11
It was 0°C. In this way, 1 r/hr from the top of the tower
I obtained a distillate of 71 K9, the composition of which was methacrylate methyl 86.83i, methyl alcohol 3-5
i1' is the ratio, water is 9.7, and the methacrylic weight is 0.
．． On the other hand, 36.48 kg of liquid from the distillation column was extracted per hour, and 3.6 out of 4.
After sending 5Kf to a thin film evaporator and removing high boiling point substances and offshore substances, it was mixed with the remaining 32.83 KI/ and circulated to the reaction tank [7].

The distillate from the distillation column was sent to an oil/water tank and separated into a methacrylate/methyl phase and an aqueous phase. The methyl methacrylate phase is separated into methyl alcohol and water by a separator.)IsL-t
``Methyl methacrylate was obtained by sending it to a rectification column.

On the other hand, the aqueous phase was mixed with methyl alcohol and water separated in a substance separation column, and then transferred to an alcohol collection column to remove most of the water and transferred to a reaction tank. Convergence of methyl methacrylate for methacrylic liquor Fi97
．． 5th grade, methyl alcohol recovery book Fi99.5
%Met.

[Brief explanation of the drawing]

Figure 1 is a process flow sheet that will be useful to anyone who will be able to implement the present invention. Year, t [Applicant Nippon Takumei Ji Gaku Kogyo Co., Ltd. Procedural Amendments Showa L October 30, 157 1 Director-General of the Office 1, Indication of given matters 1988 %'fftIll”f 174557 No. 2
, Title of the invention: Acrylic ester and method for producing methacrylic ester (3), amended person, patent user, Sohigashi-ku, Osaka, Osaka Prefecture? i6 Arashien 5-1 (462)
Representative of Nippon Shokubai Chemical Industry Co., Ltd. Tori Ishikawa Sanbe 4, agent? -100 1-2 Uchisocho, Chiyoda-ku, Tokyo, No. 2 Specification t, Section 6 of the Detailed Description of the Invention, Contents (11 Specification Homare, page 6, line 5, ``With the Tribe'') Part 2:
f....” is replaced with “Group alcohol”
Now…” I corrected myself. (2) On page 14, line 13 of the same article, it says, ``Hydro-!εnon...from the top of the tower...
``...'' is corrected to ``-1...Cihydroginone...''. that's all

Claims (1)

[Claims] (1) Acrylic rg/l or methacrylic acid carbon number 1
〜゛Mole of methacrylic acid and acrylic alcohol to be supplied as a raw material when producing an acrylic ester or methacrylic ester by esterification reaction with the lower aliphatic alcohol of 3 in the presence of an acidic catalyst The esterification reaction was carried out at a temperature of 60 to 100°C for 7 m2 with a ratio of ?1:1.0 to 2.0, the resulting esterification reaction mixture was distilled, and fresh acrylic ester Alternatively, by supplying the methacrylic ester to a distillation column, a distillate containing substantially no acrylic acid or methacrylic acid and consisting of the acrylic ester or methacrylic ester, the ester, reacted cow water, and unreacted alcohol is obtained. A method for producing an acrylic ester or a methacrylic ester, which is characterized in that a distillation column liquid from which produced water has been removed in an actual %+ manner is allowed to accumulate in an esterification reaction.