DE2200305A1 - Titanium mould with oxide coating - for casting partic battery grids - Google Patents

Abstract

Prepn. of a mould for casting partic. battery grids as well as other molten materials such as plastics, is carried out by heating a Ti surface having a cavity conforming to the shape of the article to be moulded, to a temp. sufficient to produce an oxide layer adhering to the Ti substrate and having the necessary thermal insulating properties for moulding. The rates of heating and cooling are such as to prevent thermal shock in the oxide layers.

Description

IMPROVED PROCESS FOR MANUFACTURING AZIRIDINES is the subject of this Invention is a process for the preparation of an aziridine by reacting Ammonia with an adjacent dihaloalkane in the presence of an alkali hydroxide as an acid-binding agent and with separation of the aziridine formed from the Reaction mixture, which is characterized in that the alkali hydroxide during the implementation period proportionally, either continuously or intermittently, to the Reaction mixture is added. The hydroxide can also only be used during a part be added to the reaction period, but it will be in a sufficient amount added to substantially all of the hydrogen halide formed during the reaction to be neutralized today, but the amounts of alkali hydroxide are not sufficient, to bring about substantial dehydrohalogenation of the neighboring dihaloalkane to lead.

Typical adjacent dihaloalkanes that can be used in the invention conform to the formula in which R is H, methyl or thyl and each X is independently a halogen. Examples of such compounds include the following dihaloalkanes: 1,2-dichloroethane, 1,2-dichloropropane, 1,2-dichlorobutane, 1,2-dibromoethane, 1,2-dibromopropane, 1,2-dibromobutane, 1,2- Diiodoethane, 1,2-diiodopropane, l, 2-diiodobutane, i, 2-difluoroethane, 1,2-difluoropropane, 1,2-difluorobutane, 1-chromium-2-chloroethane, 1-bromo-2-chloropropane, l- Chloro-2-bromopropane, l-bromo-2-chlorobutane and 1-chloro-2-bromobutane.

Typical aziridines formed in this process include those of the formula one in which is RH, methyl or ethyl. Examples of such aziridines are 2-methylaziridine and 2-ethvlaziridine.

The ammonia used in the invention can be either anhydrous Ammonia or an aqueous ammonia solution, e.g. an aqueous solution that 25 to 100 wt.

Contains ammonia.

Examples of suitable alkali hydroxides are lithium hydroxide, Called sodium hydroxide and potassium hydroxide. An aqueous solution is preferred of the alkali hydroxide, e.g. an aqueous solution containing 5 to £ 0 by weight of alkali hydroxide contains. Instead of an aqueous solution of the alkali hydroxide or at the same time With such a solution, solutions of alkali hydroxides in organic polar solvents, such as in alcohols, e.g. in methanol, ethanol or ethylene glycol be used.

In general, the molar ratio between the total amount of Alkali hydroxide, which is added to the reaction mixture, to the neighboring one Dihaloalkane between 0.1 / 1 and 1.1 / 1, but a ratio is preferred between 0.9 / 1 and 1/1 is used. An excess of alkali hydroxide is then not disadvantageous if the excess alkali hydroxide is added to the reaction mixture becomes after the reaction is essentially complete An excess of alkali metal hydroxide, however, adversely affects the yields in the presence of substantial amounts Amounts of alkylene halide.

In the method of the invention, the conditions can be within a varies in a wide range depending on the particular starting materials used will. In general, a temperature between 20 and 2000 is preferred C, in particular between 35 and 800 C, worked.

The conversion time varies depending on the temperature used, but the reaction usually takes a few hours, e.g. 3 to 8 hours, Completely. Carrying out the process at elevated pressure is preferred, whereby the autogenous pressure of the reaction mixture can be sufficient. Is preferred operated at a pressure of 11.5 to 22.0 kg / cm2 (150-300 psi.g).

However, higher pressures can also be used. In general the molar ratio of ammonia to neighboring dihaloalkane is between 5 / 1 and 100/1, with ratios between about 20/1 and 40/1 being preferred.

The invention is explained in more detail in the following examples. Example 1 is a comparative experiment from which it emerged that only very poor Yields of aziridine can be obtained when the alkali hydroxide in the Rcaktions- ' vessel is presented.

Example 1 (comparison test) A pressure reactor is used the one with 4 m. ethylene chloride, 80 m. ammonia, 8.8 m. anhydrous KOH and 60 g of toluene is charged. The reactor is heated to 1000 ° C. for 38 minutes. Then he will cooled, opened and the reactor contents are analyzed. Results from the analysis that the conversion of the ethylene chloride to 100 / has proceeded, whereby the .. Aziridine was formed in 11.4 'yield. From the presence of vinyl chloride it turns out that too strong a dehydrohalogenation of the ethylene chloride takes place is.

Example 2 A four liter stainless steel autoclave, the has a feed line containing 1050 g (about 62 moles) of ammonia and 200 g (about 2 ol) 1,2-dichloroethane charged. The reactor is heated to 550 C and at this Temperature held. After 90 minutes have elapsed, a 30 ¢ / aqueous Solution of sodium hydroxide into the reactor at a rate of 1.5 ml / Min. Initiated.

The sodium hydroxide solution is fed in at this rate continued for 3 3/4 hours. Then the feed rate is increased to 2 ml / Min. And sodium hydroxide solution is added until a total of 4.18 ml (about 4.2 moles) had been charged into the reactor.

After 418 ml of the sodium hydroxide solution has been added, the reactor is cooled and the reaction product is analyzed. Analysis shows 100% conversion of the 1,2-dichloroethane, with the aziridine in one yield of 60 °, based on the 1,2-dichloroethane, has arisen.

Example 3 In a one-liter pressure vessel made of stainless steel, which has a supply line possesses, 450 g of NH3 and 80 g of 1,2-dichloroethane are given. The reaction mixture is heated and held at 600 C for two hours.

After this time, a 30% aqueous solution of iQaOH is poured into the Vessel with a C7 'speed of 3.3 ml / min.

initiated. After the addition of the NaOH, the reaction temperature is increased to 650 ° C. and a further 100 ml of NaOH are added to the vessel at one speed of 3.3 ml / min.

brought in.

After the addition of Nahm, the reactor is cooled and the reaction product will be analysed. The 1,2-dichloroethane has been converted to 100% and the aziridine is produced in a yield of 60%, based on 1,2-dichloroethane.

Example 4 In a continuous operation, four in Series of reactors used. There are 6S, 6 parts by weight per hour Ammonia and 13.2 parts by weight per hour of 1,2-dichloroethane in the first reactor initiated. The autogenous pressure and temperature are used in each reactor in the individual reactors is as follows: first reactor, 420 C, second reactor, 470 C, third reactor, 480 C and fourth reactor, 450 C.

The total residence time in the reaction is 11.57 hours.

No sodium hydroxide is introduced into the first reactor; against what but in the second, third and fourth reactor partly 19, 6.4 and 422 parts by weight per hour be added to a 30% aqueous solution of NaOH The total conversion of 1,2-dichloroethane is 94.9% and the yield of aziridine 65.6E, based on 1,2-dichloroethane.

Claims (7)

Patent claims: 1 »Process for the production of an aziridine by converting ammonia with a neighboring dihaloalkane in the presence of an alkali hydroxide as the acid-binding agent Agent, characterized in that the alkali hydroxide proportionally during the reaction is added to the reaction mixture. 2. The method according to claim 1, characterized in that the alkali hydroxide is added in an amount sufficient to prevent that formed during the reaction To neutralize hydrogen halide essentially but in insufficient Amounts around a substantial dehydrohalogenesis of the neighboring dihaloalkane bring about. 3. The method according to any one of claims 1 or 29, characterized in that that the alkali hydroxide is added continuously during the reaction 4. Procedure according to one of claims 1 to 3, characterized in that the alkali hydroxide Sodium hydroxide is used. 5. The method according to any one of claims 1 to 4, characterized in that an adjacent dihaloalkane of the formula is used in which RH, methyl or ethyl and X is independently chlorine or bromine and that an aziridine of the formula arises, in which R has the meaning already given. 6. The method according to claim 5, characterized in that each X Is chlorine. 7. The method according to claim 6, characterized in that each R II is.