GB2045237A

GB2045237A - Process for producing bis (N,N- dialkylamino) alkyl ethers

Info

Publication number: GB2045237A
Application number: GB7921782A
Authority: GB
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1979-03-30
Filing date: 1979-06-22
Publication date: 1980-10-29
Also published as: IT7924113A0; IT1196398B; SE8604745L; SE447375B; SE448538B; SE7904581L; NL7904648A; GB2045237B; JPS5755709B2; FR2452477A1; SE8604745D0; SE463367B; DE2921972A1; JPS55130943A; FR2452477B1

Abstract

Bis-(N,N-dialkylamino) ethers of the formula (R2NR')2O, wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing 2 or 3 carbon atoms, are produced by a two-step, "one-pot" reaction that utilises specified molar proportions of SO3 vapour and either R2NR' ONa or R2NR'OK as reactants and is carried out in the presence of R2NR'OH, wherein R and R' are as defined above. The resulting bis-ethers are useful as catalysts in the production of polyurethanes, especially cellular polyurethanes.

Description

SPECIFICATION Process for producing bis (N, N - dialkylamino) alkyl ethers This invention relates to a process for producing bis - (N, N - dialkylamino) alkyl ethers of the formula (R2NR')2O, wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing from 2 to 3 carbon atoms. These ethers are useful as catalysts in the production of polyurethanes, especially cellular polyurethanes.

Bis [beta (N, N - dialkylamino) alkyl] ethers, including the commercially important bis [2 - (N, N dimethylamino) ethyl] ether ("BDMEE"), are known to be valuable polyurethane catalysts, particularly in the production of flexible polyurethane foam. By way of illustration, the production of polyurethane foam by reacting an organic isocyanate with an active hydrogen-containing compound (polyol) in the presence of a bis [beta - (N, N - dimethylamino) alkyl] ether catalyst is disclosed in United States No.

3,330,782.

Several processes for the production of bis beta (N, N - dimethylamino) ethyl ethers, including BDMEE, are known. One process utilizes di (2 chloroethyl) ether as a reactant as disclosed in United States Patents Nos. 3,400,157 and 3,426,072.

However, there are several disadvantages associated with the use of di (2 - chloroethyl) ether, including (a) the need to employ comparatively expensive corrosion resistant equipment because of the presence of chlorides in the reaction mixture, (b) disposal problems associated with by-product chlorides, and (c) the relatively high cost and lack of ready availability of di (2 - chloroethyl) ether. Another process for the production of bis[beta - (N, N dimethylamino) alkyl] ethers involves reacting a[beta - (N, N dimethylamino) alkanol], a beta - (N, N dimethylamino) alkyl chloride and an alkali metal hydroxide using a modified Williamson synthesis as disclosed in United States Patent No. 3,480,675.

However, this modified Williamson synthesis has several disadvantages, including (a) several solidshandling steps, (b) a discontinuous mode of operation, (c) disposal problems associated with byproduct sodium chloride, and (d) one of the reac tants, 2 - dimethylaminoethyl chloride, used in the production of BDMEE is an unstable liquid and is also a vesicant which requires special handling. A further process for the production of BDMEE comprises reacting trimethylamine with 2 -[2 - (N, N dimethylamino) ethoxy] ethanol in the presence of a nickel catalyst under superatmospheric pressure as disclosed in United States No. 3,957,875. However, this process requires the use of a costly highpressure reactor and provides product yields that leave room for improvement.Accordingly, it is desirable to provide a process for the production of bis - (N, N - dialkylamino) alkyl ethers, including BDMEE, that does not possess the disadvantages associated with the above-mentioned processes.

It is an object of this invention to provide a process for the production of bis - (N, N - dialkylamino) alkyl ethers, including BDMEE, from relatively inexpensive, readily available starting materials.

It is a further object of this invention to provide a process for the production of bis - (N, N - dialkylamino) alkyl ethers that gives improved product yields.

It is another object of this invention to provide a process for the production of bis - (N, N - dialkylamino) alkyl ethers that is essentially a "one pot" process in order to minimise the need for material transfer.

It is still another object of the invention to provide a process for the production of bis - (N, N - dialkylamino) alkyl ethers by a liquid phase reaction that avoids the necessity of solids handling steps.

The present invention relates to a process for producing a bis - (N, N - dialkylamino) alkyl ethers having the formula (R2NR')2O, wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing from 2 to 3 carbon atoms. The process of the invention comprises: (a) reacting sodio N, N - dialkylaminoalkoxide of the formula R2NR'ONa, wherein R and R' are defined above, with from 0.1 to 0.8 (prefer ably from 0.40 to 0.55) moles of SO3 vapour per mole of sodio N, N - dialkylaminoalkoxide at a temperature of up to about 90"C (prefer ably from 20"C to 50"C) in the presence of:: (I) an N, N - dialkylaminoalkanol of the for mula R2NR'OH, wherein R and R' are defined above, that is present in an amount such that the molar ratio of sodio N, N - dialkylaminoalkoxide to N, N - dial kylaminoalkanol ranges from 1:0.5 to 1:3 and, optionally, (II) an organic diluent/dispersant (preferably in an amount ranging from 10 to 50 weight percent, based upon the amount of sodio N, N - dialkylaminoalkoxide and N, N - dialkylaminoalkanol employed), to produce an intermediate reaction product mixture, (b) heating the intermediate reaction product mixture from step (a) to an elevated tempera ture and maintaining the elevated tempera ture for a time period sufficient to produce bis - (N, N - dialkylamino) alkyl ether, and (c) recovering the bis - (N, N - dialkylamino) alkyl ether.

In another aspect of the present invention, potassio N, N - dialkylaminoalkoxide is employed instead of sodio N, N - dialkylaminoalkoxide in the above specified process.

This bis - (N, N - dialkylamino) alkyl ethers produced in accordance with the process of the present invention are useful as catalysts in the production of cellular polyurethanes. One such catalyst, [bis 2 - (N, N - dimethylamino) ethyl] ether, is particularly useful in the production of flexible polyurethane foam.

The reaction according to the process of the present invention is a two-step reaction that can be depicted as follows:

wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing from 2 to 3 car bon atoms. Although the process of the present invention can be carried out continuously, it is pre ferred to carry it out as a "one-pot" batch process.

The sodio dialkylaminoalkoxide reactant can be produced by reacting sodium hydroxide with N, N, dialkylalkanolamine at about 100"C and removing the water by-product by distillation. The sodio dial kylaminoalkoxide reactant can also be prepared by dissolving sodium metal in N, N - dialkylal kanolamine. Useful sodio dialkylaminoalkoxides include, for example, sodio - 2 - N, N dimethylamino - ethoxide, sodio 1 - N, N dimethylamino - 2 - propoxide, sodio 3 - N, N dimethylamino - 1 - propoxide, sodio 2 - N, N - diethylamino - ethoxide, sodio 1 - N, N - diethylamino - 2- propoxide, and sodio 3 - N, N - diethylamino - 1 propoxide. The potassio dialkylaminoalkoxide reactant can be produced by an analogous method (e.g.

by reacting potassium hydroxide with N, N - dial kylalkanolamine and removing the water by-product by distillation). Useful potassio dialkylaminoalkox ides would include the potassio analogs of the above-listed sodio compounds such as, for example, potassio - 2 - N, N - dimethylaminoethoxide and potassio 1 - N, N - dimethylamino - 2- propoxide.

The sodio dialkylaminoalkoxide reactant is utilised in solution with the corresponding dialkylaminoalkanol (characterised by the formula R2NR'OH, wherein R and R' are as defined above) in the reaction mixture. The dialkylaminoalkanol acts as a solvent for the sodio dialkylaminoalkoxide. Thus, for example, sodio 2 - N, N - diethylaminoethoxide is used in solution with N, N - diethylethanolamine; sodio 2 - N, N - dimethylaminoethoxide is used in solution with N, N - dimethylethanolamine, and sodio 3 - N, N - dimethylamino - 1 - propoxide is used in solution with 3 - N, N - dimethylamino - 1 - propanol. The dialkylaminoalkanol is employed in order to ensurethatthe sodio dialkylaminoalkoxide remains soluble in the reaction mixture during Step 1 of the reaction and does not crystallize out the mixture.The molar ratio of sodio cialkylamino - alkoxide to the corresponding dialkylaminoalkanol is not narrowly critical and generally ranges from 1:0.5 to 1:3 (preferably from 1:1 to 1 :2). The lower the temperature, the higher the proportion of the dialkylaminoalkanol required to keep the alkoxide in solution. Conversely, as the temperature if Step 1 approaches 90"C, the proportion of alkanol to alkoxide can become less than 1:1. The reaction according to the process of the present invention can alternatively be effected by substituting potassio dialkylaminoalkox ide for sodio dialkylaminoalkoxide.

The organic diluent'dispersant useful in the process of the present invention can serve three functions. First, it acts as a diluentforthesodio dialkylaminoalkoxide reactant, thereby moderating the rate of the sodio dialkylaminoalkoxide/sulfurtrioxide reaction and reducing the likelihood of charring during that reaction. Second, it acts as a dispersent and co-solvent (together with the dialkylaminoalkanol) for the sodio dialkylaminoalkoxide, preventing the crystallization of the sodio dialkylaminoalkoxide during Step 1 of the reaction. At high ratios of dialkylaminoalkanol to alkoxide, a large proportion of an organic diluent also could be used without causing precipitation of the contained alkoxide, with the usable limit being dictated by economics.Third, it optionally serves as a "pot-boiler" during recovery of this bis - (N, N - dialkylamino) alkyl ether. Useful diluent'dispersants must both (a) not readily react with sulfur trioxide when incorporated into the reaction mixture and (b) have a boiling point of at least about 90"C (preferably at least about 100"C) at atmospheric pressure.Such a boiling point will ensure that the reaction will occur within a commercially acceptable time period since the reflux temperature (and, hence, reaction temperature) that is achievable for the reaction mixture is directly related to the boiling point of the diluent'dispersent In addition, provided that the boiling point of the diluent(dispersant is at least about 10 C higher than that of the bis-ether product, it will function as a "pot-boiler" for recovery of the bis-ether. For its use as a "pot-boiler", the diluent'dispersant can be added at any stage before the distillation is carried out.Useful diluentidispersants include straightchained hydrocarbons such as n-heptane, n-octane and n-tetradecane; mixed straight-chained, mixed branched-chained and mixed straightchained/branched-chained hydrocarbons containing a number of carbon atoms per molecule of from 6 to 30; and ethers such as tetrahydrofuran, dioxane, monoglyme and diglyme. Toluene was found to be unacceptable diluent'dispersant since it readily reacted with a sulfurtrioxide reactant.

The amount of diluentidispersant employed according to the process of the present invention can vary widely depending upon the particular reactants and diluent'dispersant used, as well as upon temperature. Generally, the diluent'dispersant is present in an amount ranging from 0 to 60 (preferably 10 to 50) weight percent based on the amount of sodio N, N - dialkylaminoxide and N, N - dialylaminoalkanol employed in the reaction mixture. When the reaction temperature of choice is in the upper part of the preferred range of from 20 to 50 C, there results improved solubility of the alkoxide without the necessity of as much organic diluent or any more dialkylaminoalkoxide. When the N, N - dialkylaminoalkanol is employed in a relatively large amount (i.e. an amount such that the molar ratio of sodio N, N - dialkylaminoalkoxide to N, N - dial kylaminoalkanol ranges from 1:2.5 to 1 :3), the reaction can be effected without employing a diluentidispersant The sulfurtrioxide useful in the process of the invention is employed as a vapour in an amount of from 0.25 to 0.60 (preferably from 0.40 to 0.55) miles of SO3 vapour per mole of sodio N, N - dialkylaminoalkoxide reactant. Care must be taken in the introduction of sulfur trioxide vapour into the reaction mixture in order to avoid (a) excessive exothermicity with corresponding degradative side reaction and (b) blockages at the side of sulfurtrioxide introduction.Preferably, the sulfurtrioxide is mixed with an inert diluent such as, for example nitrogen or argon, prior to introduction into the reaction mixture.

The reaction according to the process pf the invention is preferably effected using an apparatus such as that described in Example 1, infra. The design of the scrubber and the positioning of the sulfurtriox- ide inlet tube are important considerations in the use of such an apparatus. The scrubber should be "selfcleaning", i.e. any solids which form and separate from the reaction mixture will be washed down into the reactor by the liquid in the reaction mixture.Useful scrubber designs include: downwardly-pointing spirally-placed protuberances; a "disk and doughnut" configuration, as employed in the stripping section of an artisan stripper; a "dual-flow" configuration, wherein perforated trays are fixed in a horizontal position in a cylindrical column; and, a series of flat plates placed either horizontally or at a downward angle from the horizontal in a descending spiral fashion. In contrast, the presence of solids in the reaction mixture can cause scrubber blockage if conventional packing materials such as Raschig rings or glass beads are employed in the scrubber.

The sulfur trioxide feed line in the above-mentioned apparatus should be above the top of the liquid mixture in the reactor in order to avoid line blockage caused by any solids that might be present or formed in the reaction mixture.

The limits on the reaction time for the process of the invention are not narrowly critical and can vary over a wide range. Because Step 1 of the reaction proceeds rapidly upon addition of the SO3 to the reactor, the time period required for Step 1 is limited solely by the rate of SO3 addition that can be achieved while maintaining the temperature of the reaction mixture within the specified limits. Generally, a suitable time period for Step 1 is from 0.5 to 10 hours (preferably from 0.5 to 4 hours). In Step 2 of the reaction, the reactants are heated to an elevated temperature (preferably from 100 C to 1200C) for a time period sufficient to produce the bis - (N, N dialkylamino) alkyl ether product.The time period required for Step 2 is generally from 1.5 to 12 hours (preferably from 1.5 to 5 hours).

Atmospheric pressure is generally employed in the process of the invention, although super- or sub-atmospheric pressures can be used if desired for some purpose.

Recovery of the bis (N, N - dialkylamino) alkyl ether product can be effected by any known method.

The preferred method involves a stripping distillation at the end of the reaction sequence. Using such a technique, the process is clearly a "one-pot" process since product recovery can be made directly from the reactor.

As indicated above, the process of the present invention is useful in preparing bis (N, N - dialkylamino) alkyl ethers characterised by the formula (R2NR')2O wherein R and R' are as defined above. Bis (N, N - dialkylamino) alkyl ethers encompassed by the formula include; bis beta (N, N - dimethylamino) ethyl ether, bis beta (N,N - dimethylamino) - 1 methylethyl ether, bis beta (N, N - dimethylamino) propyl ether, bis 3 - (N, N - dimethyl - amino) propyl ether, bis beta (N, N - diethylamino) ethyl ether, bis beta (N, N - diethylamino) - 1 - methylethyl ether, and bis beta (N, N - diethylamino) propyl ether. The preferred bis (N, N - dialkylamino) alkyl ether is BDMEE.

Other tertiary amine-containing bis-ethers, not encompassed by the above formula, that may be produced according to the process of the instant invention include:

and

As has been indicated above, such ethers are useful as catalysts in the production of cellular polyurethanes.

The following Examples are illustrative of, but are not intended to limit, the present invention.

EXPERIMENTAL The following experimental description illustrates the present invention. In the experimental description, the following abbreviations are used: Abbreviation Meaning BDMEE bis 2 - (N, N - dimethylamino) ethyl ether Diluent I A hydrocarbon mixture consisting of the following composition Paraffin Weight Percent Normal Paraffin C12 0.02 Normal Paraffin C13 0.49 Normal Paraffin C14 66.95 Normal Paraffin C15 31.79 Normal Paraffin C16 0.53 Isoparaffins 0.22 Diluent II n-heptane Diluent Ill n-octane percent weight percent mm millimeter EXAMPLEI Synthesis of BDMEE using Diluent The apparatus consisted of a 3-litre, 4-necked jacketted reactor equipped with a bottom outlet, a scrubber, a mechanical stirrer, a thermometer and a gas inlet tube. The bottom outlet was connected to the inlet of a pump.The outlet of the pump was connected by means of a jacketted circulation line to the top of the scrubber. The scrubber consisted of a glass column containing spirally-placed dimples wherein the dimples pointed downward. Atop the scrubber was located a reflux condenser which was connected to a source of dry nitrogen. The gas inlet tube was connected to a source of sulfur trioxide sparged with nitrogen.

The synthesis of bis 2 - (N, N - dimethylamino) ethyl - ether was carried out as follows: Into the reac tor were charged 2.69 moles of sodio 2 - (N, N dimethylamino) ethoxide and 4.44 moles of N, N dimethylethanolamine at about 50"C. to this mixture was added 464.7 grams of Diluent I. The resulting mixture was cooled to 250C with stirring. A small amount of solids formation occurred at this point.

With continued stirring, circulation of the mixture through the scrubber was begun. A vapour of sulfur trioxide and nitrogen gas, produced by sparging nitrogen through liquid sulfur trioxide at a rate of 80 to 148 cubic centimeters of nitrogen per minute, was passed into the reactor through the gas inlet tube at a rate such that 1.17 moles of sulfurtrioxide were added over a period of about three hours while the stirred mixture was maintained at 25"C. Afterthe addition of the entire amount of sulfurtrioxide to the reactor, stirring of the reaction mixture was continued for 30 minutes, and then the reaction mixture was heated to a temperature of 115"C and maintained at that temperature with stirring for three hours.Completion of the reaction was indicated by the reduction of the sodio - 2 - N, N dimethylaminoethoxide concentratorto a constant low level. The reaction product was distilled through an entrainment separator or short column until the head temperature reached 1300C to produce a distillate consisting of N, N - dimethylethanolamine and the BDMEE product in addition to a small amount of Diluent I. Redistillation of this broad-range distillate through a 35-tray Oldershaw column provided BDMEE as a fraction boiling at 880C at 25 mm. The yield of BDMEE was between 63 and 68 percent, based on sulfurtrioxide employed.

EXAMPLE2 Synthesis of BDMEE using Diluent Using the apparatus of Example 1,445.5 grams (5.0 moles) of N, N - dimethylethanolamine and 472.5 grams of Diluent I were added to the reactor.

The mixture was stirred and circulated through the scrubber. A vapour mixture of sulfurtrioxide and nitrogen, produced by sparging nitrogen gas through liquid sulfur trioxide at a rate of about 100 cubic centimeters per minute, was passed into the gas inlet tube of the reactor over a period of about three hours until 1.71 moles of sulfurtrioxide had been added to the reactor, while the stirred mixture in the reactor was maintained at 25"C. Upon completion of the addition of sulfur trioxide to the reactor, a hot (65"C) solution of 3.6 moles of sodio - 2 - N, N dimethylaminoethoxide in 5.54 moles of N, N dimethylethanolamine was added to the stirred mixture in the reactor. The resulting mixture in the reactor was heated to 1100Cand maintained at that temperature with stirring for three hours.The reaction product was distilled at 7 mm pressure through an entrainmentseparatorto remove the BDMEE and excess N, N - dimethylethanolamine. The distillate contained 1.05 moles of BDMEE ethanolamine. The distillate contained 1.05 moles of BDMEE which rep resented a yield of 61.4 percent, based on sulfur trioxide employed.

EXAMPLE3 Synthesis of Bis 2 - (N, N - diethylamino) ethyl ether using Diluent II Using the apparatus of Example 1, a solution of 2.43 moles of sodio - 2 - N N - diethylaminoethoxide in 4.57 moles of N, N - diethylethanolamine at about 50"C was added to the reactor. To this mixture was added 514 grams of Diluent II. The resulting mixture was cooled to 25"C with stirring and then circulated through the scrubber.A vapour mixture of sulfur trioxide and nitrogen, produced by sparging nit rogen gas through liquid sulfur trioxide at a rate of about 148 cubic centimetres per minute, was passed into the gas inlet tube of the reactor over a period of about 2 hours and 10 minutes until 1.01 moles of sulfur trioxide had been added to the reactor, while the stirred mixture in the reactor was maintained at about 24"C. Upon completion of the addition of sulfurtrioxide to the reactor, the mixture was stirred for one hour and then heated to a reflux temperature of 110"C. The mixture was refluxed with stirring for 11 hours, and then it was cooled and filtered through a kiesel-guhr-coated filter.The filtrate was distilled through a 35-tray Oldershaw column to give 0.39 moles of bis 2 - (N, N - diethylamino) ethyl ether as a fraction boiling at 1200C at 15 mm. The yield of bis 2 - (N, N - diethylamino) ethyl ether was 39 percent, based on sulfur trioxide employed.

Example 4 Synthesis of Bis 3 - (N, N - dimethylamino) propy ether using Diluent Ill Using the apparatus of Example 1, a solution of 2.35 moles of sodio 3 - N, N - dimethylamino - 1 propoxide in 4.15 moles of 3 - N, N - dimethylamino 1 - propanol at about 50"C was added to the reactor.

To this mixture was added 300 grams of Diluent Ill.

The resulting mixture was cooled to 250C with stirring and then circulated through the scrubber. A vapour mixture ofsulfurtrioxide and nitrogen, produced by sparging nitrogen gas through liquid sulfur trioxide at a rate of about 148 cubic centimeters per minute, was passed into the gas inlet tube of the reactor over a period of about 2 hours and 10 minutes until 1.07 moles of sulfur trioxide has been added to The reactor, while the stirred mixture in the reactor was maintained at about 25"C. Upon compietion of the addition of sulfurtrioxide to the reactor, the mixture was stirred for one hour and then heated to a reflux temperature at 125"C. The mixture was refluxed with stirring for 12 hours, and then it was cooled and filtered through a kielsguhr-coated filter.

The filtrate was distilled through a 35-tray Oldershaw column to remove lower-boiling material, and the remaining mixture was distilled through a 10-tray Oldershaw column to give 0.36 moles of bis 3 - (N, N - dimethylamino) propyl ether as a fraction boiling at 86 to 880C at 5 mm. The yield of bis 3 - (N, N - dimethylamino) propyl ether was 34 percent, based on sulfurtrioxide employed.

EXAMPLES Synthesis of Bis 2 - (N, N - dimethylamino) - 1 methylethyl ether using Diluent I.

Using the apparatus of Example 1, a solution of 2.48 moles of sodic 1 - N, N - dimethylamino - 2 propoxide in 4.92 moles of 1 - N, N - dimethylamino 2 - propanol was added to the reactor. To this mixture was added 553 grams of Diluent I. The resulting mixture was cooled to 18"C with stirring and then circulated through the scrubber. A vapour mixture of sulfurtrioxide and nitrogen, produced by sparging nitrogen gas through liquid sulfur trioxide at a rate of about 148 cubic centimeters per minute, was passed into the gas inlet tube of the reactor over a period of about two hours until 1.17 moles of sulfur trioxide had been added to the reactor, while the stirred mixture in the reactor was maintained at about 20"C.

Upon completion of the addition of sulfur trioxide to the reactor, the mixture was stirred for 30 minutes and then heated to 115DC. The mixture was held at 115"C with stirring for 2 hours and 45 minutes, and then it was distilled through an entrainment separator at 5 mm pressure in order to produce a distillate containing bis 2 - (N, N - dimethylamino) 1 - methylethyl ether, excess 1 - N, N dimethylamino - 2 - propanol, and a small amount of Diluent I. Redistillation of this broad range distillate through a 35-tray Oldershaw column provided 0.57 moles of bis 2 - (N, N - dimethylamino) - 1 methylethyl ether as a fraction boiling at 115 to 117 C at 50 mm. The yield of bis 2 - (N, N - dimethylamino) - 1 - methylethyl ether was 49 percent, based on sulfurtrioxide employed.

Claims

1. A process for producing a bis - (N, N - dialkylamino) alkyl ether having the formula (R2NR')2O, wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing from 2 to 3 carbon atoms, which comprises: (a) reacting sodio N, N - dialkylaminoalkoxide of the formula R2NR'ONa, wherein R and R' are as defined above, with from 0.1 to 0.8 moles of SO3 vapour per mole of sodio N, N - dial kylaminoalkoxide at a temperature of up to about 90"C in the presence of: (I) an N, N - dialkylaminoalkanol of the for mula R2NR'OH, wherein R and R' are as defined above, that is present in an amount such that the molar ratio of sodio N, N - dialkylaminoalkoxide to N, N - dial kylaminoalkanol ranges from 1:0.5 to 1 ::3, and, optionally, (II) an organic diluent'dispersantto produce an intermediate reaction product mixture, (b) heating the intermediate reaction product mixture from step (a) to an elevated tempera ture and maintaining the elevated tempera ture for a time period sufficient to produce bis - (N, N - dialkylamino) alkyl ether, and (c) recovering the bos - (N, N - dialkylamino) alkyl ether.

2. A process for producing a bis - (N - N - dialkylamino) alkyl ether having the formula (R2NR')2O, wherein R is a methyl or ethyl group and R' is a bivalent alkylene group containing from 2 to 3 carbon atoms, which comprises: (a) reacting sodio N, N - dialkylaminoalkoxide of the formula R2NR'ONa, wherein R and R' are as defined above, with from 0.25 to 0.60 moles of SO3 vapor per mole of sodio N, N dialkylaminoalkoxide at a temperature of from 20"C to 90"C in the presence of: (I) an N, N - dialkylaminoalkanol of the for mula R2NR'OH, wherein R and R' are as defined above, that is present in an amount such that the molar ratio of sodio N, N - dialkylaminoalkoxide to N, N - dial kylaminoalkanol ranges from 1:1 to 1 ::3, and (II) an organic diluent/dispersant in an amount ranging from 0 to 60 weight per cent based on the amount of sodio, N, N dialkylaminoalkoxide and N, N - dial kylaminoalkanol employed, to produce an intermediate reaction product mixture, (b) heating the intermediate reaction product mixture from step (a) to an elevated tempera ture and maintaining the elevated tempera ture for a time period sufficient to produce bis -(N, N - dialkylamino) alkyl ether, and (c) recovering the bis - (N, N - dialkylamino) alkyl ether.

3. A process as claimed in claim 1 or claim 2 wherein the amount of SO3 vapour ranges from 0.40 to 0.55 moles per mole of sodio N, N - dialkylaminoalkoxide.

4. A process as claimed in any one of the preceding claims wherein step (a) is carried out a temperature of from 20"C to 50"C.

5. A process as claimed in any one of the preceding claims wherein the organic diluentidispersant is employed in an amount of from 10 to 50 weight percent, based on the amount of sodio N, N - dialkylaminoalkoxide and N, N - dialkylaminoalkanol employed.

6. A process as claimed in any one of the preceding claims where the molar ratio of sodio N, N - dialkylaminoalkoxide to N, N - dialkylaminoalkanol is from 1:1 to 1:2.

7. A process as claimed in any one of the preceding claims wherein the bis - (N, N - dialkylamino) alkyl ether is bis beta - (N, N - dimethylamino) ethyl ether, the sodio N, N - dialkylaminoalkoxide is sodio 2 - N, N - dimethylaminoethoxide, the N, N - dialkylaminoalkanol is N, N - dimethylethanol amine, and the diluent'dispersant is a mixture of aliphatic hydrocarbons containing from 6 to 30 carbon atoms.

8. A process as claimed in any one of claims 1 to 6 wherein the bis - (N, N - dialkylamino) alkyl ether is bis beta - (N, N - diethylamino) - ethyl ether, the sodio, N, N - dialkylaminoalkoxide is sodio 2 - N, N diethylaminoethoxide, the N, N - dialkyminoalkanol is N, N - diethylethanolamine, and the diluent'dis- persant is a mixture of aliphatic hydrocarbons containing from 6 to 30 carbon atoms.

9. A process as claimed in any one of claims 1 to 6 wherein the bis - (N, N - dialkylamino) alkyl ether is bis 3 - (N, N - dimethylamino) propyl ether, the sodio N, N - dialkylaminoalkoxide is sodio 3 - N, N dimethylamino - 1 - propoxide, the N, N - dial kylaminoalkanol is 3 - N, N - dimethylamino - 1 propanol, and the diluent/dispersant is n - octane.

10. A process as claimed in any one of claims 1 to 6 wherein the bis - (N, N - dialkylamino) alkyl ether is bis beta - (N, N - dimethylamino) - 1 - methylethyl ether, the sodio N, N - dialkylaminoalkoxide is sodio 1 - N, N - dimethylamino - 2 - propoxide, the N, N dialkylaminoalkanol is 1 - N, N - dimethylamino - 2 propanol, and the diluent'dispersant is a mixture of aliphatic hydrocarbons containing from 6 to 30 carbon atoms.

11. Aprocesswhich comprises: (a) reacting sodio 2 - N, N - dimethylaminoethox ide, with from 0.40 to 0.55 moles of SO3 vap our per mole of sodio N, N dimethylaminoethoxide at a temperature of from 20 C to 500C in the presence of: (I) N, N - dimethylathanolamine in an amount sufficient to produce a molar ratio ofsodio 2 - N, N dimethylaminoethoxideto N, N dimethylethanolamine of from 1:0.5 to 1::3,and (II) an organic diluentldispersant in an amount ranging from 10 to 50 weight per cent, based on the amount of sodio 2 - N, N - dimethylaminoethoxide and N, N dimethylethanolamine, for a time period sufficient to produce an intermediate reaction product mixture, (b) heating the intermediate reaction product mixture from step (a) to an elevated tempera ture and maintaining the elevated tempera ture for a time period sufficient to produce bis 2 - (N, N - dimethylamino) ethyl ether, and (c) recoveringthe bis 2 - (N, N - dimethylamino) ethyl ether.

12. A process as claimed in claim 1 substantially as hereinbefore described.

13. A process as claimed in claim 1 substantially as hereinbefore described in any one of the specific Examples.

14. A modification of a process as claimed in any one of the preceding claims wherein a potassio N, N - dialkylaminoalkoxide is used in place of the sodio N,N- dialkylaminoalkoxide.

15. A bis - (N, N - dialkylamino) - alkyl ether when produced by a process as claimed in any one of the preceding claims.

16. A polyurethane when produced using, as a catalyst, a bis - (N, N - dialkylamino) - alkyl ether as claimed in claim 15.