DE2709138A1 - PROCESS FOR THE PRODUCTION OF 2-CHLORACETACETIC ACID ESTERS - Google Patents

Description

270913Ö

2-chloroacetoacetic acid esters can be obtained by chlorinating Acetoacetic acid esters (see Liebig's Annalsn, 3d. 2 '* 5, page 59).

In the known method, the total amount of the acetoacetate is used submitted and in the course of a few hours by introducing a stream of chlorine to the desired Brought to Urasetzung cirad. However, this method has the disadvantage that the chlorination must be stopped at relatively low conversions because of the selectivity of the 2-chloroacetoacetic acid ester is strong at higher sales going back. However, low Unisatz cause a high distillation requirement for recycling unconverted acetoacetic acid ester 5.

A second method of making chlorinated acetoacetic acid esters (Organic Syntheses, Vol. 33 »page 45) uses sulfuryl chloride instead of chlorine. This procedure is ongoing Although up to very high sales with good yield, it has the disadvantage that instead of the cheaper chlorine, sulfuryl chloride must be used, the sulfur dioxide formed in the reaction in a separate operation must be converted back into sulfuryl chloride.

Although a poorer chlorination result was to be expected with a continuous procedure, because the entire Heat of reaction occurs in a very short reaction time, a process has surprisingly been found in which the selectivity of the 2-chloroacetoacetic acid ester is essential despite the rapid merging of the reactants can be increased.

The process for the preparation of 2-chloroacetoacetic acid

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esters of chlorine and acetoacetic acid esters)! is characterized by that chlorine and acetoacetic acid ester in a wood ratio of 0.5 to 1.3 ί 1, preferably 0.3 to 1.2: 1, continuously in direct current, whereby the input

o The temperature of the reactants enters the reaction space -20 C

to +30 ° C, preferably 10 to 20 ° C.

With the molar ratio found, it is achieved that not too much Acetoacetic acid ester must be recycled or more by-products are formed, which at a high molar Chlorine: acetoacetic acid ester ratio arise.

Any continuously operating device be used, which meet the conditions of good heat dissipation and simultaneous introduction of the Keaktionskoi.iponentsn im Direct current guaranteed.

The usual cooling devices are used to dissipate the reaction temperature, in the simplest case a cooling jacket through which water at from II to 25 ° C. flows.

A suitable reaction tube is, for example, a simple tube which is surrounded by a cooling jacket and into which the two components are introduced separately, mixed and made to react. Further expedient, continuously operating systems are reactors in which a tube bundle, preferably a tube coil, is used instead of a tube. An advantageous reactor is also a thin-film reactor, for example a fall-filter reactor, as shown in the drawing below.

The residence time of the reactants in the reaction space is usually 0.5 to 5 min. The person skilled in the art knew that to achieve

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thorough mixing and, in order to avoid local heating, the flow velocity must be selected so high that one gets into the area of a turbulent flow. It is all the more surprising that even at flow velocities well below the velocities at which turbulent flows occur and therefore local overheating can be expected, the difference between discontinuous reaction and continuous reaction, as Table I shows, is so great at higher conversions .

Table I below shows the yields of ethyl 2-chloroacetoacetate I and ethyl 2-chloroacetoacetate II, as well as the selectivity of the chlorination of ethyl acetoacetate 1 and ethyl acetoacetate II as a function of the dilution. The entrance tapes

The temperature of the reactants in the reaction chamber is 20 C.

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Tabel

:! ι.ι
V. ί-et
.iCetes- I. discontinuous
process 00 mola
res Ci ₂ /
Esters yield
ratio Mon 1% I continuous process Mon 1% Silver snake S. mola
res Cl ₀ /
Esterver
ratio - educ. .40 S. II continuous
procedure 40 mola
res Ci ₂ /
Ester compound
ratio Yield sigic acid 00 Ko IJi Mon 1% • 75 20th MoITi estcr 00 34.00 34 .20 20th 5 00 0.46 40.50 Glass snake 42 3C.5O 0.44 35 • 50 Falling film reactor 20th - 09 MoIJJ 00 0.59 45.60 50 S7.50 O.56 43 .uO O
CO 00 0.74 49.70 57 87.00 Ο.67 52 .25 Mon 150 _ _ OO
u> 05. 50 0.90 51.20 mola
res Cl _n /
S ester yield
ratio 64 85.00 o.fio 59 .90 0.79 60.40 σ> Ci. 1.08 49.50 Mon 1%. 70. 53.50 0.93 66 0.92 67.36 ο 50 76. 1.30 45.12 73. «2.50 I.05 74 1.06 73.03 ! ^ GO 71. 1.44 Π7.00 or 45 02.00 1.12 77 I.13 76.19 ο 70. 64. 35.ΟΟ 0.57 . w0 86. CO 55. 83.50 0.69 30th 84. 90 47. 82.00 October 2nd .10 Cl. 95. 80.00 Ο.96 40 uU · 7Ü.5O 1.09 00 . 00 77.50 1.16 65 .00 G2 .00 00. 00 00 co

S = 3e.lfäktivit; it

Ans'). = Yield of Z-chloroacetic acid ester based on the amount of acetoacetic acid ester used

ro

te co

CJC

As the comparison between uer reaction in the glass snake and the Silberschlanoe shows animal heat dissipation is of some importance at high Unsützen of acetoacetates. The best yields can be expected if good heat dissipation is provided , which can be achieved by using a reactor made of silver or a silver-plated material.

The use of liquid chlorine improves both the selectivity of the desired 2-chloroacetoacetic acid ester and its yield.

An advantageous embodiment of the present method is that the reaction is carried out under a pressure of 1-10 atmospheres, preferably 3-5 atmospheres above the vapor pressure of liquid chlorine at the respective inlet temperature of the reactants in the reaction area. This measure causes a faster solution of the chlorine in acetoacetate, whereby at the same time the heat of reaction that occurs is reduced in terms of quantity, since the heat of condensation that occurs ues chlorine is removed before the reactants meet, which results in a more favorable selectivity with respect to the 2-chloroacetoacetic acid ester.

Further control of the reaction rate and distribution of the heat of reaction along the direction of flow results from a corresponding inlet temperature

the reactant in the reaction chamber, which is preferably is set to 10-20 ° C. The lowering of the inlet temperatures below the preferred range brings about

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Although still better yields of 2-chloroacetoacetic acid esters, as well as an Improvement of the selectivity, however, has the relevant disadvantage that instead of cooling water with expensive cooling brines are worked, which have to be laid around the inlet lines of the reactants.

The processes according to the invention result in higher yields of 2-chloroacetoacetic acid esters achieved than in the known processes in which chlorine is used as the chlorinating agent will. This effect occurs in particular with high conversions of acetoacetic acid esters, which is also associated with an advantageous selectivity with respect to what is desired 2-chloroacetoacetic acid ester is linked.

As an ester of acetoacetic acid, which according to the invention Processes are monochlorinated in the 2-position, aliphatic esters come into consideration, expediently Esters of monohydric alcohols containing up to 10 carbon atoms, preferably alcohols with 1-4 carbon atoms such as methyl acetoacetate, Ethyl acetoacetate, butyl acetoacetate or isobutyl acetoacetate.

The 2-chloroacetoacetic acid esters are used for the manufacture used by coumaric acid derivatives, which are known as an intermediate in the manufacture of pesticides. The compounds prepared according to the invention can also can even be used as a pesticide.

Comparative Examples Batch Reaction

In a 1 liter round bottom flask, which is in a thermostat

/8th

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ο
with which the temperature in the round bottom flask is reduced to 20 C

can be kept, 600 g (5il6 mol) of methyl acetoacetate submitted. A chlorine stream of 15 l / h (0.67 mol / h), which has a temperature of 20 C, initiated with vigorous stirring. That means a molar ratio of chlorine: methyl acetoacetate such as 0.52 t 1. The yield of the methyl 2-chloroacetoacetate obtained based on the amount of methyl acetoacetate used is 37 mol% and the selectivity of Compound 33.15 mole percent. The values were taken from the gas rroraatograms determined on the basis of a calibration curve prepared beforehand using nitrobenzene as an internal standard.

If instead of 15 l / h chlorine 27 »7 l / h (1.23 mol / h) chlorine
are introduced, which means a molar ratio of chlorine: methyl acetoacetate such as 0.958: 1, the yield of methyl 2-chloroacetoacetate, based on the amount of methyl acetoacetate used, is 18 mol 5 * and the
Selectivity of the compound 68.74 mol *.

If chlorine quantities are used which lead to the molar chloroacetoacetic acid methyl ester ratios described in Table 1, column discontinuous process, the conversions shown there with regard to methyl acetoacetate and the yields and selectivities mentioned there with regard to methyl 2-chloroacetoacetate are determined by means of the gas chromatograms mentioned.

Example I.

A silver tube with an inner diameter of 6 tnm and a length of 1.4 m is rolled up in 5 turns and fitted with a rubber stopper into a glass tube as a cooling jacket. Cooling water from II C is passed through the cooling jacket. A constant flow of 300 ml acetoacetic acid is passed through the pipe coil.

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acid ethyl ester / h (2.78 mol / h) is pumped, while a chlorine stream of 32 l / h (l, 42 Hol / h) is introduced at the same time. This corresponds to a chlorine pick-up ratio; Ethyl acetate as 0.51: 1 «The feed of the chlorine is done through a polyethylene tube, the end of which is narrowed to 3 mm in diameter and protrudes 150 mm into the silver tube. The inlet temperature of the reactants

ο in the reaction room is 20 C. The samples are according to the comparative example analytisiort. The yield of 2-chloroacetoacetic acid methyl ester is 40.23 Molft, the selectivity 87.91 Mo1 #. If a chlorine flow of 60 l / h (2.67 mol / h) is used instead of 32 l / h, if a molar ratio of chlorine: acetoacetic acid methyl ester of 0.967: 1 corresponds, the yield of 2-chloroacetoacetic acid ethyl ester is 69 _t l MoIÄ and the selectivity 83.19 MoISi.

Are the amounts of chlorine used in accordance with those listed in Table I under Section Silberschlang · molar chlorine: acetoacetic acid methyl • ester ratios, then those recorded there are recorded Conversions with respect to methyl acetoacetate and the yields and selectivities mentioned there with respect to methyl 2-chloroacetoacetate were found by means of the gas chromatography mentioned.

Example 2

Under the same conditions as in Example 1, the chlorination of methyl acetoacetate is carried out in a glass tube which has the same ' Has dimensions like those of the silver tube. If a chlorine flow of 60 l / h (2.67 mol / h) with a constant

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Stream of 300 ml of methyl acetoacetate (2.78 mol / h) is brought together, the yield of methyl 2-chloroacetoacetate is based on the amount of methyl acetoacetate used, 64.36 mol? 6, the selectivity 79.9 moles 9E.

If amounts of chlorine are used which lead to the molar chlorine: methyl acetoacetate ratios described in Table I under Section Glass Coil, the conversions shown there with regard to methyl acetoacetate and the yields and selectivities mentioned there with regard to methyl 2-chloroacetoacetate are found by means of the gas chromatograms mentioned.

Example 3

The apparatus (see Fig. 1) consists of an outer tube 1 provided with a cooling jacket 6 and a ribbed, cooled inner tube 7. 5.5 kg (42.26 mol) of ethyl acetoacetate are passed directly to the head of the inner tube 7 via line R every hour so that it flows off continuously and evenly distributed on the outer surface of the inner tube. At the same time, a continuous stream of chlorine of 900 l / h (40.18 mol / h) is passed into the outer tube space via line R, to which a manometer 4 is connected. The molar ratio of chlorine to ethyl acetoacetate is 0.95: 1. The cooling water of the inner pipe and the outer pipe with the inlets 6a and 7a, as well as the outlets 6b and 7b has a temperature of 11 C. The temperature of the reactants entering the reaction chamber is 20 C. At the lower end of the tube, the reaction products hydrogen chloride and ethyl chloroacetoacetate emerge together and are separated at separator 2. In the template 31 which is connected to an exhaust pipe 5, collects

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the product, which is still approx. 7? » Contains hydrogen chloride. The analyzes are carried out according to the comparative example. This results in a yield of ethyl 2-chloroacetoacetate, based on the amount of ethyl acetoacetate used, such as 66.59 mol%. The selectivity is 83.5 moles #.

Are chlorine quantities used, those described in Table I under section falling film reactor molar chlorine: lead Acetessigsäureäthylester- ratios, so the indicated there conversions are relative Acetessigsäureixthylester and referred to therein yields and selectivities hinsicntlich 2-Chloracetessigsäureäthylester by means of said gas chromatograms found.

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Le

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Claims (2)

1. Process for the preparation of 2-chloroacetoacetic acid esters from chlorine and acetoacetic acid esters:!, Thereby gek O λ η ζ ei ch η et that one chlorine and acetoacetic acid ester in molar ratio 0.5 to 1.3 '· 1, preferably O, G up to 1.2: 1, continuously combined in direct current, vobci the initial temperature of the reactants in de » Roaktioi is. Rcaktionsraui -20 C to +30 C, preferably 10 to 20 C, 2. The method according to claim 1, characterized in that the reaction is durchfjefiihrt under a pressure aer 1 to 10 atmospheres, preferably 3 to atmospheres übar the vapor pressure of liquid chlorine at the respective £ intrittste: .iperatur the Seaktanten in the lieaktionsrauci is . / 2 809836/0210 ORIGINAL INSPECTED