DD257742A3 - PROCESS FOR THE PREPARATION OF DIOXOLANE (METH) ACRYLATES - Google Patents

Abstract

The invention relates to a process for preparing dioxolane (meth) acrylate by transesterification with basic catalysts, wherein hydroxydioxolane are reacted with (meth) acrylate in the presence of pulverfoermigem alkali metal alcoholate solvent-free. The Temperaturfuehrung and catalyst addition carried out in such a way that the alcohol formed as a by-product is removed by distillation from the equilibrium. As the alkali metal alkoxide, sodium methylate or the sodium alcoholate of hydroxymethyldioxolane is preferably suitable.

Description

formula 1

be reacted with (methyl) acrylic acid ester in the presence of alkali metal alkoxide, wherein R ¹ , R ^{2 are the} same or different aliphatic or aromatic radicals. According to the invention, solvent-free alkali metal alcoholate is used in substance. The process can be advantageously carried out so that the transesterification takes place at temperatures of 80 to 120 ⁰ C, preferably at 85 ° C. For the achievement of optimally possible yields of dioxolane (meth) acrylates, it is advantageous to remove the alcohol formed during the transesterification by distillation. As the alkali metal alkoxide, sodium methylate or the sodium salt of the respective hydroxydioxolane is preferably suitable. With particular advantage, according to the transesterification process according to the invention (2,2-dimethyl-1,3-dioxolan-4-yl) of methyl methacrylate of formula 2 can be produced.

CH ₂ - CH- | -CH ₂ OH X ^0, I / °

CH-CH ₂ -OC-CCH = CH ₂

The hydroxymethyldioxolanes reacted as starting compounds can be prepared simply from the alcohols and ketones by the customary synthesis methods as described, for example, in Organikum: Organisch-chemisches Praktikum, Berlin 1984. The invention will be explained below with 3 examples.

Embodiment 1

The reaction vessel is charged with 700 ml of methyl methacrylate, 150 g of 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane and 3 g of hydroquinone. After about 5 minutes, 3 g of finely powdered sodium methylate are added with stirring and the reaction mixture is heated to 85 ° C. internal temperature. After reaching this temperature, the resulting methanol can be separated continuously. Two more portions of sodium methylate are added after 2.5 and 5 hours of reaction, respectively. After a reaction time of 8 hours, filtered (of formed polymethyl methacrylate or Polydioxolanmethacrylat, about 150 g) distilled off excess methyl methacrylate and then the distillation residue is fractionated Kp 70-72 ° C / 0.4mbar, yield 170g (75%).

d ²⁰ = 1.0511 g-cm " ³

C ₁₀ H ₁₆ O ₄ calc .: C 59.58 H 8.05

(200,23) found: 59,59 8,04

Polymer content <5%; Isopropylideneglycerol content: <10%

Embodiment 2

1.4 kg of methyl methacrylate, 28 g of hydroquinone and 0.27 kg of 4-hydromethyl-2,2-dimethyl-1,3-dioxolane are introduced into a 2.5 l sulfonating flask with stirrer and attached distillation apparatus. Under stirring in inert gas flow thereto is added sodium alcoholate of 0,13kg Hydroxymethyldioxolans used and heated to 95-100 ⁰ C internal temperature. After every 1.5 hours, two further portions of 0.13 kg each of the catalyst are added. At the same time, two further portions of 0.675 kg each (stabilized with 4% hydroquinone) of methyl methacrylate are added. Thereafter, the reaction is continued until no more methanol-methacrylic acid methyl ester mixture distilled over (refractive index control of the distillate). The remaining reaction mixture is worked up by distillation to recover excess methyl methacrylate. This gives 250 g (62%) of analytically pure (2,2-dimethyl-1,3-dioxolan-4-ylmethyl methacrylate.

d ²⁰ = 1.0511g-crrT ³ ; , Found .: C 59.56 H 8.03.

Polymer content: 7%; Isopropylideneglycerol content: <10%

Embodiment 3

In a reaction vessel, to 50 g of isopropylidene glycerol, 202 ml of methyl methacrylate and 2 g of naphthol, 5.5 ml of a solution of 2 g of sodium in 40 g of methanol are added. The mixture is heated to 110 ^° C. outside temperature. In total, 16 ml of the catalyst solution are added, in 3.5 ml portions after every 2 hours. The mixture turns green-brown in color and becomes viscous. It is filtered, distilling off excess MMA. Crude yield: 59g; Thin-layer chromatography: (benzene / alcohol 9: 1 as eluent, detection: methanolic iodine solution). In addition, isopropylidene glycerol and the dioxolane methacrylate contain two more compounds, they have about the same Rr value as the target product.

It is fractionated in vacuo. To obtain an analytically pure product, it is necessary to fractionate three times. Yield: 28 g (37.5%) Kp 70-72 / 04mbar.

Found: C 59.50 H 8.04; d_ ² ° = 1.0511 g · cm " ³ .

Polymer content: 44%; Isopropylideneglycerol content:> 10

Claims (2)

1. A process for the preparation of Dioxolanmethacrylaten by transesterification of methacrylic acid esters with hydroxydioxolanes of formula 1, in which R ¹ and R ^{2 are the} same or different aliphatic or aromatic radicals, at temperatures of 80-120 ° C in the presence of alkali metal, characterized that solvent-free alkali metal alkoxide is used in substance. 2. The method according to claim 1, characterized in that is used as the alkali metal alcohol sodium methylate or the Natriumalkoholat of Hydroxyalkyldioxolans. Field of application of the invention The invention relates to a process for the preparation of Dioxolanimethjacrylaten by transesterification. The compounds mentioned have, because of their special structure, namely to possess two polymerizable functional groups, a variety of applications. They are used as a polymerizable component in adhesives, for example in the optical industry. In addition, they play a role as mechanically stable, well-adhering coatings on glass and metal. Their fields of application are where methyl methacrylate has application significance. Characteristic of the known technical solutions It is known that dioxolane (meth) acrylate can be prepared by transesterification of the methylol compound with (meth) acrylic acid methyl ester. In Houben-Weyl "Methods of Organic Chemistry" Bd. XIV / 2, 567 and in US 2680735 methods are described in which a solution of sodium in methanol to the mixture of methyl methacrylate and 2,2-dimethyl-4-hydroxymethyl-dioxolane ( Since the transesterification reaction is an equilibrium reaction, ie from dioxolane methacrylate and methanol form again methyl methacrylate and hydroxymethyldioxolane, arises - for kinetic reasons - with reduced yield, a difficult to be purified by distillation product mixture The aim of the invention is to develop a transesterification method for the preparation of dioxolane (meth) acrylates, which makes it possible to produce the target product in good yields, and to develop the transesterification process according to the present invention at the problems of destilla intensive cleaning does not occur. Explanation of the essence of the invention The invention has for its object to develop a transesterification process for the preparation of dioxolane (meth) acrylates, which is conducted so that without special technological and synthetic chemical effort, the easily to be purified by distillation target product.
The object is achieved in that Hydroxydioxolane of formula 1