JPS6123184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for the continuous production of peroxydicarbonates in high purity. In the field of polymerization, peroxydicarbonate
RO-C(O)-OO-C(O)-OR has recently gained considerable importance as an initiator. Because they are peroxyester initiators R-C
This is because it can be used in a considerably lower amount than (O)-OO-R. However, one drawback of peroxydicarbonates, especially in the production process, is their inherent instability. For example, diisopropyl peroxydicarbonate (IPP) and di-n-propyl peroxydicarbonate (NPP)
Peroxydicarbonates such as are very thermally sensitive and are also very sensitive to mild shocks. Under certain conditions, all of the above compounds are prone to explosion. For example, if left at room temperature, IPP
decomposes with intense gasification and the vapors can ignite spontaneously. Therefore, the production of peroxydicarbonate is
Precautions must be taken to avoid decomposition due to heat or shock. Dangerous explosions have occurred during the production of pure products in industrial batch processes where economically large quantities are handled. Other conventional alternatives have been to use diluents or inert solvents in the process and sell thin products. For example, U.S. Pat. No. 3,377,373 describes the continuous production of peroxydicarbonates by reacting a chloroformate (or chlorocarboxylic ester) with hydrogen peroxide and an aqueous alkali metal hydroxide solution in at least two reaction zones. The method is described. The reaction is stopped in the last or later reaction zone by adding a halogenated organic solvent or a liquid halogen-free hydrocarbon solvent. This solvent solution is then separated by using various settling vessels, washing vessels and the like. A similar continuous method using a solvent is described in US Pat. No. 3,429,910. However, the use of solvents reduces processing efficiency;
Additionally, since pure (undiluted) peroxydicarbonate is desired in many polymerizations, a continuous, solvent-free process increases processing efficiency and
Moreover, it would be highly desirable to develop a process that could result in a polymerization industry where either pure or dilute products are selected. Broadly speaking, the present invention provides for the production of chloroformic acid esters of the formula RO-C(O)-Cl, where R is alkyl of 2 to 16 carbon atoms, in at least two reaction zones connected in series. by sequentially reacting hydrogen peroxide and an aqueous alkali metal hydroxide at temperatures ranging from approximately -10°C to +50°C to obtain the formula RO-C.
In an improved solvent-free process for the continuous production of (O)-OO-C(O)-OR peroxydicarbonates, the (undiluted) reaction mixture from the last of the above reaction zones is continuously fed into a centrifuge to separate the peroxydicarbonate product (organic phase) with a purity of at least about 97%. Optionally, the above purity is further achieved by continuously mixing the separated organic phase from the centrifuge with a saturated solution of salt in a mixing zone and continuously subjecting the organic phase-salt solution mixture to another centrifuge. It can be increased to at least about 98% by recovering the organic phase again. Even higher (to at least 99%) purity improvements as well as water,
The reduced content of chloroformates and chlorides is
Achieved by continuously passing the organic phase recovered from said second centrifuge through a stripping zone where the product is subjected to stripping with dry air or other oxygen-containing gas in a stripping column. can do. The present invention will be described in detail below. It has been discovered that peroxydicarbonates can be produced safely and continuously in high purity in an efficient solvent-free process by separating the pure product using a centrifuge. The basic methodology involved in this improvement is substantially described in US Pat. No. 3,377,373, so reference is made to that US patent as appropriate. More specifically, the formula RO-C(O)-OO-
Each R in C(O)-OR is ethyl, isopropyl,
2 to 2 carbon atoms, including linear or branched alkyl, cycloalkyl, and substituted or unsubstituted alkyl, such as butyl, 2-ethylhexyl, benzyl, cyclohexyl, 2-phenoxyethyl, tetradecyl, cetyl, and the like. Peroxydicarbonates having the above formula individually selected from 16 (preferably 3 to 8) alkyls are advantageously produced in high purity (at least about 97% assay) by an improved continuous process. It was discovered that it could be manufactured. The reaction of the chloroformate ester RO-C(O)-Cl (wherein R is as previously defined) with aqueous hydrogen peroxide and aqueous alkali metal hydroxide is carried out using at least two series-connected Apparatus including jacketed reactors 14 and 16 and centrifuge 18 at approximately -10°C.
It is carried out at a temperature in the range from about +50°C, preferably from about 10 to 30°C. Normally, two reactors connected in series are generally sufficient; however, when dealing with less reactive chloroformate esters (such as when R has 13 to 16 carbons), more than two reactors are sufficient. may be desired to prolong the residence time in the reaction zone.The reactants are continuously fed from storage vessels 2, 4 and 6 via metering devices 8, 10 and 12 into reactor 14 at controlled flow rates. and the majority of the reaction (usually 90-95%) takes place in the reactor, with the temperature of the reaction mixture being within ±20°C of the desired temperature (usually about 20-35°C in reactor 14). The reaction mixture is then kept in the second reactor 16.
, where the remainder of the reaction takes place. Since there is a slight heating during centrifugation, the temperature in this second reactor is preferably lowered to about 9-11°C. Both reactors have
Efficient stirring and cooling means are provided as described in US Pat. No. 3,377,373. The cooled reaction mixture is then continuously fed to a centrifuge to separate the peroxydicarbonate product. Some of the peroxydicarbonates are solids (e.g., when R is cyclohexyl, tetradecyl, and cetyl) and are recovered in a liquid-solid centrifuge, but most are liquid and are thus recovered in a liquid-liquid centrifuge. Collected using a centrifuge. The organic phase contains the peroxydicarbonate product which is separated from the aqueous phase. Although any conventional centrifuge such as a basket type, ball type, or flat disk type can be used, a flat disk type centrifuge was used in the example described later. The aqueous phase (stream 20) is discarded, while the product 22 (of at least about 97% purity) is delivered directly from the centrifuge to a container as product. Alternatively, this product can be transferred to mixing tank 2
4, it is further processed by continuous mixing with a saturated salt solution added at a controlled flow rate from storage tank 26 through metering device 28. Mixing tank 24
The temperature in reactors 14 and 16 (which, like reactors 14 and 16, are equipped with means of stirring and cooling) is
Again, it is preferably maintained at a temperature near the low temperature part of the desired range, usually about 10°C. The mixed solution is then continuously fed to another centrifuge 30 of the type described above to separate a product (stream 34) of at least 98% purity. The aqueous phase (stream 32) is also discarded here. If higher purity (at least about 99% assay) and lower alkyl chloride, chloroformate and water content are desired, the product stream 34 from the centrifuge 30 is fed to a stripping zone, usually packed or plated. It is continuously fed to a stripping column where it is fed with dry air or other oxygenated gas at ambient temperature.
8 (usually counter-current or cross-current). The glass preferably has a theoretical plate number of at least 2. The product 40 can be packaged as such (in pure form) or diluted with various solvents (eg toluene, acetone, methylcyclohexane, odorless mineral spirits). Storage tanks 2, 4, 6, 26 and control means 8, 1
0, 12, 28 may be constructed of any type of material that is compatible with or compatible with the reactants to be stored or pumped. Mixing tank 2
4 can be made of glass or stainless steel, and reactors 14 and 16 are preferably made of stainless steel. The reactor 14 is also equipped with a PH meter for monitoring the reaction PH so that it is in the range of 8 to 14 (preferably 10 to 12). Chloroformate starting material is at least about 90%
(preferably at least 97-98%). When the starting material is purer, the second centrifuge and stripper can often be eliminated. 30-70% aqueous hydrogen peroxide (preferably 50%) and 10-50% alkali metal hydroxide (preferably 20% sodium or potassium hydroxide) aqueous solutions are advantageously used as other starting components. . These reactants are hydrogen peroxide
Mixed in a ratio of 0.9 to 1.1 (preferably 1.0) moles to 2.0 to 2.2 (preferably 2.0) moles of chloroformate to 1.9 to 2.4 (preferably 2.0) moles of aqueous hydroxide. The saturated salt solution can be a variety of aqueous inorganic salts, such as ammonium, sodium chloride, sulfate and phosphate (preferably sodium chloride), and the amount of the solution is typically greater than the first centrifuge. approximately equal to the amount of product produced from The above explanation is
Defines a method and apparatus for producing symmetrical (same R groups) peroxydicarbonates, whereas hybrid percarbonates are produced by combining two chloroformate esters (different R groups) in reactor 1.
4. Other parts of the process are the same. The following examples illustrate the invention without limiting it. Flow rates are in parts by weight/hr (pph) unless otherwise specified. Reactors 14 and 1
6 is made of stainless steel, and the mixing tank 24 is made of glass. The centrifuges 18 and 30 are flat disc type liquid-liquid centrifuges for desludging. Example Continuous production of di-sec-butyl peroxydicarbonate (SBP) - The reactant flow rate to obtain a product amount of 30 pph is:
Di-sec-butyl chloroformate 50 pph, 50% aqueous
H ₂ O ₂ was 19.5 pph and 20% aqueous NaOH was 99 pph. The temperature of reactor 14 was maintained at 35±1°C, and that of reactor 16 was maintained at 10±1°C. This was accomplished by circulating cooling brine through the reactor cooling jacket. Centrifuge 18
Product stream 22 from had an average assay of 97.5%. Product stream 22 and 30 pph of saturated sodium chloride solution were mixed in wash tank 24 and then passed through centrifuge 30, resulting in product stream 3.
4 had an average assay higher than 98%. Example Preparation of di-n-propyl peroxydicarbonate (NPP) - Using the apparatus (i.e. both centrifuges 18 and 30) and method of the example (with the exception that reactor 14
n-propyl chloroformate 85 pph, 50% aqueous H ₂ O ₂ 31 pph, 20%
From NaOH169pph and saturated NaCl solution 50pph,
NPP was produced at a flow rate of 50 pph and an average assay >98%. Example Preparation of diisopropyl peroxydicarbonate (IPP) - Isopropyl chloroformate
IPP was prepared from 85 pph, 50% H ₂ O ₂ 28.5 pph, 20% NaOH 160 and 50 pph of saturated NaCl solution at a flow rate of 50 ppm and average assay >98%. EXAMPLE - To demonstrate the effect of stripping product stream 34 by passing dry air through packed column 36 at room temperature on assay and chloride content, the procedures in Example and were followed.
Additional experiments regarding IPP and SBP are illustrated in the table below. 【table】

[Brief explanation of the drawing]

The accompanying figure is a schematic flow sheet illustrating the invention. Explanations of symbols representing main parts in the attached drawings are as follows. 2, 4, 6, 26: storage tank, 8, 10, 12,
28: Measuring device, 14, 16: Reactor with jacket, 18, 30: Centrifuge, 24: Mixing tank or washing tank, 36: Stripping column.

Claims (1)

[Claims] 1. In at least two reaction zones connected in series, a chloroformate ester RO-C(O)-Cl (R is an alkyl having 2 to 16 carbon atoms), hydrogen peroxide and -10°C to +50°C with aqueous alkali metal hydroxide
Peroxydicarbonate RO-C(O)-OO-C by continuous reaction at a range of temperatures
In a continuous process for the production of (O)-OR, the peroxydicarbonate product is produced by continuously feeding the solvent-free reaction mixture from the last of the reaction zones directly into a centrifuge and recovering the organic phase. The above-mentioned manufacturing method, characterized in that the separation is performed with a purity of at least 97%. 2. The manufacturing method according to claim 1, wherein R is alkyl having 3 to 8 carbon atoms, and the centrifuge is a liquid-liquid centrifuge. 3 Claim 2 in which R is isopropyl
Manufacturing method described in section. 4 Claim 2 in which R is sec-butyl
Manufacturing method described in section. 5 Claim 2 in which R is n-propyl
Manufacturing method described in section. 6. Chloroformic acid ester RO-C(O)-Cl (R is alkyl of 2 to 16 carbon atoms), hydrogen peroxide and aqueous alkali metal hydroxide in at least two reaction zones connected in series. -10℃～＋50℃
Peroxydicarbonate RO-C(O)-OO-C by continuous reaction at a range of temperatures
In a continuous process for the production of (O)-OR, the peroxydicarbonate product is produced by continuously feeding the solvent-free reaction mixture from the last of the reaction zones directly into a centrifuge and recovering the organic phase. with a purity of at least 97%, and the separated organic phase is further mixed continuously in a mixing zone with a saturated solution of salt,
Then, in another centrifuge to collect the organic phase,
A process as described above, characterized in that the mixed organic phase-salt solution is fed continuously to separate a peroxydicarbonate product of at least 98% purity. 7. The manufacturing method according to claim 6, wherein R is alkyl having 3 to 8 carbon atoms, and both centrifuges are liquid-liquid centrifuges. 8 Claim 7 in which R is isopropyl
Manufacturing method described in section. 9 Claim 7 in which R is sec-butyl
Manufacturing method described in section. 8. The manufacturing method according to claim 7, wherein 10R is n-propyl. 11. Chloroformic acid ester RO-C(O)-Cl (R is alkyl of 2 to 16 carbon atoms), hydrogen peroxide and aqueous alkali metal hydroxide in at least two reaction zones connected in series. -10℃～＋50
By continuously reacting at temperatures in the °C range,
Peroxydicarbonate RO-C(O)-OO-
In a continuous process for the production of C(O)-OR, peroxydicarbonate production is carried out by continuously feeding the solvent-free reaction mixture from the last zone of the reaction zone directly into a centrifuge and recovering the organic phase. the separated organic phase is further mixed continuously in a mixing zone with a saturated solution of salt,
Continuously feed the mixed organic phase-salt solution to another centrifuge to recover the organic phase until at least 98%
The purified peroxydicarbonate product is separated and the organic phase recovered from this second salt center is further passed continuously to a stripping zone where it is subjected to stripping with dry oxygenated gas in a column. and also at least 99
% pure peroxydicarbonate product. 12 R is alkyl having 3 to 8 carbon atoms, and both centrifuges are liquid-liquid centrifuges, Claim 1
The manufacturing method according to item 1. 13. The manufacturing method according to claim 12, wherein 13R is isopropyl. 13. The manufacturing method according to claim 12, wherein 14R is sec-butyl. 13. The manufacturing method according to claim 12, wherein 15R is n-propyl.