Description:FIELD OF THE INVENTION
[001] The invention relates to the manufacturing of 2-amino-1,1-dimethoxyethane or Aminoacetaldehydedimethyl acetal (AADMA) and more particularly relates to the continuous manufacturing of AADMA in a flow reactor.
BACKGROUND OF THE INVENTION
[002] Amino-acetaldehyde dimethyl acetal ( AADMA) is a colourless liquid which primarily finds application as an intermediate for manufacturing active pharmaceutical ingredients. The molecular structure of amino acetaldehyde dimethyl acetal is as given hereunder,

[003] Synthesis of 2-amino-1,1-dimethoxyethane or Aminoacetaldehydedimethyl acetal (AADMA) is generally accomplished through batch processes which need longer reaction times for completion. Moreover, the batch processes for AADMA are endowed with many side reactions that can affect the overall purity of the end product namely AADMA. The general route of synthesis of AADMA comprises of treating Chloroacetaldehyde dimethyl acetal with aqueous ammonia under the conditions of higher pressures. Prior art throws light on many such references that have dealt with the synthesis of AADMA.
[004] Patent CN103739506 disclosed a method for preparing aminoacetaldehyde dimethyl acetal which comprised the steps of 1) adding dimethyl chloroacetal and an ammonia aqueous solution with a concentration of 10-40% into a container at a time, uniformly stirring; 2) stirring the reaction solution in step 1), heating the reaction solution to 100-150 DEG C; 3) performing distillation of the reaction solution in step 2), recovering the ammonia water till no obvious fraction is distilled out; 4) adding a sodium hydroxide aqueous solution with a concentration of 20%-50% into the reaction solution in step 3), adjusting the pH to 12-14; 5) performing rectification of the solution in step 4), and collecting colourless and light yellow transparent liquid which is the target product, aminoacetaldehyde dimethyl acetal.
[005] US2490385A disclosed a process for the production of aminoacetal from chloroacetal which comprised heating chloroacetal with anhydrous ammonia in the absence of alcohol and other solvents and in a proportion within the range of approximately 15 to 25 mols of ammonia per mol of chloroacetal at temperature within the range of 115° C to 125° C at a superatmospheric pressure of approximately 100 atmospheres pressure for a period sufficient to effect substantially complete conversion of the chloroacetal.
[006] CN111875510 disclosed a method for preparing aminoacetaldehyde dimethyl acetal from chloroacetal using liquid ammonia at temperatures ranging between 70°C-100°C, and pressure maintained at 2.0MPa-3.0MPa., liquid alkali with a mass fraction of 30%-50%, to adjust solution pH value to12-13 and methanol and ammonia gas are recovered by vacuum distillation before the target product aminoacetaldehyde dimethylacetal is obtained by vacuum distillation.
[007] CN105906514 disclosed a preparation method of amino aminoacetaldehyde dimethyl acetal comprising steps of firstly adding chloroacetaldehyde dimethyl acetal and methyl alcohol in a pressure reaction kettle, mixing them uniformly; then adding liquid ammonia, heating up to 150 degrees centigrade for high pressure reaction; adding intermediate materials into a concentration kettle, carrying out distillation several times, reducing the pressure of distillation each time until the methyl alcohol is recovered successfully, and centrifugally filtering the solution; adding sodium hydroxide in the centrifugal liquid to regulate its Ph value; conducting rectification and extraction dehydration under a normal pressure,
[008] US4792630 disclosed a process for preparing aminoacetaldehyde dialkyl acetals, which comprises reacting a halogenoacetaldehyde dialkyl acetal with ammonia or an alkylamine in an aqueous medium in the simultaneous presence of an alkali metal hydroxide or of an alkaline earth metal hydroxide, and distilling the resulting reaction mixture reaction is carried out at about 80° to 150° C. and a pressure of about 3 to 20 kg/cm2.
[009] CN103739601 disclosed a method for preparing praziquantel, which is a one-pot method and comprised production of aminoacetaldehyde dimethyl acetal in the first step by: performing an ammonolysis reaction of chloroacetaldehyde dimethyl acetal and an ammonia aqueous solution to generate aminoacetaldehyde dimethyl acetal.
[010] CN110015964 disclosed a technology for producing aminoacetaldehyde dimethyl acetal wherein Chloroacetaldehyde dimethyl acetal is firstly synthesized into aminoacetaldehyde dimethyl acetal by using ammonia solution containing carbon dioxide, aminoacetaldehyde dimethyl acetal and carbon dioxide are then converted to hydroxymethyl aminopropyl formic acid, after deamination, hydroxymethyl propylcarbamic acid is decomposed into aminoacetaldehydedimethyl acetal and carbon dioxide after high temperature and acid aqueous reflux. After recovering carbon dioxide, aminoacetaldehyde dimethyl acetal hydrochloride is obtained, and then aminoacetaldehyde dimethyl acetal hydrochloride is neutralized, distilled, and rectified to obtain high purity aminoacetaldehyde dimethyl acetal.
[011] CN112375003 disclosed a production process of high-purity aminoacetaldehyde dimethyl acetal by proportionally mixing chloroacetaldehyde dimethyl acetal with anhydrous liquid ammonia to react, and carrying out ammoniation, deamination recovery, alkali neutralization, desalination, distillation and rectification in the presence of an iodine-containing catalyst to obtain the high-purity aminoacetaldehyde dimethyl acetal.
[012] US4137268A disclosed a method of preparing aminoacetaldehyde acetals by the hydrogenation of dialkoxyacetonitrile by contacting a dialkoxyacetonitrile with hydrogen at an elevated pressure and at a temperature of 50-180° C., preferably in the presence of a catalyst and preferably in the presence of ammonia.
[013] Though the prior art showed many references dealing with the manufacturing of AADMA, many of these processes are highly energy intensive and are associated with lower yields. Further, most of them employed a catalyst to initiate the conversion of CADMA to AADMA which can become an additional burden when it comes to the question of separation and regeneration of the catalyst at the down-stream.
[014] Keeping the above aspects into consideration, the instant invention of “ A process for continuous manufacture of 2-amino-1,1-dimethoxyethane or AADMA” is taken up in a flow reactor that can reduce the reaction time considerably, improve the product characteristics namely purity and yield, and minimize the operational costs.
[015] The exemplary aspects of various embodiments of the invention are disclosed in the summary of the invention and all the essential aspects related to various embodiments of the invention are described in a detailed manner in the following paragraphs with specific references towards the corresponding figures as given hereunder. All the prior art references are incorporated hereby in their entirety and for reference-sake and in no way taking away the novelty of the instant invention. The various aspects of the instant invention disclosed here are definitely an improvement over the existing prior art and further stress upon the inventorship, novelty and applicability of the instant invention
OBJECTIVES OF THE INVENTION
1. To come out with a continuous process for manufacturing 2-amino-1,1-dimethoxyethane or aminoacetaldehyde dimethylacetal in a flow reactor that can reduce the residence time considerably and can offer improved product purity and higher yields.
2. To come out with a continuous, catalyst-free process for manufacturing aminoacetaldehyde dimethylacetal in a flow reactor that minimizes operational costs.
SUMMARY OF THE INVENTION
[016] The exemplary aspect of the invention discloses a continuous method for the production of aminoacetaldehyde dimethylacetal (AADMA) characterized by the pumping of chloroacetaldehyde dimethylacetal (CADMA) and aqueous ammonia(>/=25% NH3 dissolved in water) along with intermittent additions of gaseous ammonia through a continuous flow reactor under pressures >/= 15bars and temperatures >115oC for a specified residence time and the reaction mass obtained at the outlet of the reactor is extracted with NaOH and distilled to obtain ~99% pure AADMA with yield of 65%.
[017] Another important aspect of the instant invention discloses employment of aqueous ammonia along with intermittent additions of gaseous ammonia for obtaining AADMA with improved purity and yield.
[018] One important aspect of the invention discloses a catalyst-free continuous method for the production of aminoacetaldehyde dimethylacetal in a flow reactor.
[019] Yet another aspect of the invention discloses a continuous process for the manufacturing of AADMA in a flow reactor that is economical compared to batch processes in terms of reduction in operation costs and manpower.
[020] One preferred embodiment of the invention discloses a continuous process for manufacturing AADMA that is safer and that can produce AADMA at a higher rate per unit-reactor-volume per unit-time, which is comparatively higher than that of corresponding batch processes.
[021] The various aspects of the instant invention are described in detail in the following paragraphs.
DETAILED DESCRIPTION OF THE INVENTION
[022] The examples of the apparatus discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. It will be understood by one of skill in the art that the apparatus is capable of implementation in other embodiments and of being practiced or carried out in various ways. Examples of specific embodiments are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[023] Any references to examples, embodiments, components, elements or acts of the apparatus herein referred to in the singular may also embrace embodiments including a plurality, and any references in plural to any embodiment, component, element, or act herein may also embrace embodiments including only a singularity (or unitary structure). References in the singular or plural form are not intended to limit the presently disclosed apparatus, its components, acts, or elements.
[024] The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. The various embodiments of invention are described in detail herein and the various aspects of the invention are disclosed below.

[025] DEFINITIONS
AADMA is Amino acetaldehyde dimethyl acetal.
CADMA is Chloro acetaldehyde dimethyl acetal.
NH3 is ammonia.
GC is gas chromatography.
GC-MS is gas chromatography coupled with Mass spectrometry for the simultaneous separation and identification of the constituents of the experimental samples.
Dimer Bis(2,2-dimethoxyethyl) amine, is an impurity and its structure is:

Flow reactor or Plug Flow reactor or Tubular Flow reactor consists of cylindrical pipes with reactants moving through one end and product coming out of another end. Reaction takes place continuously as they flow down the length of the reactor. Static mixers can be provided inside these pipes for efficient mixing.
Residence time is the time the reactants stay in the flow reactor before the completion of the reaction and rectification of the end product namely AADMA starts and is expressed in hours.
CADMA : NH3 mole ratio is 1: 25/>25
INSTRUMENTAL ANALYSIS:
[026] The purity of the final product and percentage yield of AADMA are obtained by performing GC analysis and GC-MS analysis of the reaction products at regular intervals at different experimental conditions. The conditions under which the GC and GC-MS analyses were performed are given below. GC and GC-MS analyses of the experimental samples are done under similar conditions taking identical columns, carrier gas and sample volumes at similar temperatures.
GC ANALYSIS:
[027] GC analysis of the experimental samples was done by maintaining the GC at the following conditions: Keeping the Column: SH-Rtx-624 30m, 0.32mm, 1.8µm, Cat. # 221-75864-30 at an Inlet temperature of 200 °C; Injection at a Split ratio of 50:1; carrier gas Nitrogen at a flow rate of 2.5ml/min; Injection volume of 0.5 microlitre; Detector temperature at 230° C; Airflow of 400mL/min; H2 flow of 40mL/min; using MeOH as diluent; Septum purge flow at 3mL/min.; Column oven temperature at 60° C, holding for 4 min; and the makeup gas Nitrogen flow at 25mL/min. The chromatogram indicated CADMA elution from the column after 11.2 min and AADMA elution from column after 11.8 min.
GC-MS ANALYSIS:
[028] GC-MS analysis of the experimental samples was done on a quadrupole MS using EI-detection method under similar GC conditions as given above to arrive at the purity of the reaction products.
METHODOLOGY
GENERAL DESCRIPTION OF THE MANUFACTURING PROCESS OF AADMA CONTINUOUS FLOW REACTOR:
[029] Chloroacetaldehyde dimethylacetal (CADMA) and aqueous ammonia (>25 wt% (30 to 50%) dissolved NH3) are made to flow in a tubular reactor (with provision for internal mixing) in the flow ratio of 1: 7 to 14, using metering pumps. The reactor is maintained at a constant temperature (100 to 150OC) through an external heating utility. The total residence time in the reactor is maintained in the range of 1-4 hours. Also, gaseous ammonia is added intermittently at intervals of 15, 30, or 45 minutes. The system pressure is maintained >15 bar using a back pressure regulator.
[030] Flow rate of CADMA is changed in the range of 15 ml/hr to 100 ml/hr. The flow rate of aqueous ammonia is maintained in the range of 100 ml/hr to 800 ml/hr. The flow rate and available flow reactor volume determines the residence time for reactants, which varied from1 hour to 4 hours. Samples are collected at regular intervals to establish the conversion and selectivity.
[031] The flowing reaction mass is continuously depressurized, cooled and collected in a receiving vessel. The collected reactor outlet is further processed to recover the organic product mass by addition of sodium hydroxide pellets. This has led to complete removal of dissolved ammonia from the mass. The addition of sodium hydroxide is continued till pH is > 12. Two layers of liquid are separated out. The organic top layer contained >90% of the product AADMA. The bottom aqueous layer is sent for effluent treatment. The experiments are conducted in both flow and batch modes for the comparative evaluation of the efficiency of the continuous flow process over batch process and the results obtained are given in the following paragraphs.
GENERAL EXPERIMENTAL PROCEDURES APPLICABLE TO FLOW AND BATCH PROCESSES
[032] A calculated quantity of CADMA and aq. ammonia solution are charged into the reactor. The reaction mixture is allowed to stir thoroughly, and the temperature of the reaction mixture is maintained through an external heating utility. Upon reaching the specified temperature, the pressure of the system is held constant. Samples of 10 ml volume are withdrawn on hourly basis and the organic layer is extracted using NaOH and the purity analysis is done by subjecting the experimental samples after NaOH treatment to GC and GC-MS analysis.
PROCEDURES PERTAINING TO CONTINUOUS FLOW PROCESS OF AMINOACETALDEHYDE DIMETHYLACETAL (AADMA)
[033] Reaction mixture is let into the flow reactor with the help of Pump-1 and Pump-2. Pump-1 was used to pump chloroacetaldehyde dimethylacetal (CADMA) (feed-1) and Pump-2 was used to pump aqueous ammonia consisting of >25% of NH3 in water (feed-2) into a flow reactor. The residence time in the reactor was maintained at 60 minutes. The pressure inside the reactor was maintained at 15 bars with the help of a back pressure regulator. After exiting the reactor, the reaction mass was collected into a bottle and the unreacted ammonia gas was flashed out and scrubbed down with aqueous HCl. The reaction mass was treated with NaOH pellets to separate out the formed AADMA into the organic layer. The organic layer was distilled to obtain pure AADMA.
CONTINUOUS FLOW REACTION
[034] The starting material CADMA is fed into the flow reactor alongside aqueous ammonia (>25%), typically in the flow ratio of 1:(7-14). The feed streams undergo intense mixing and are preferably heated to 110-130 ⁰C. The pressure inside the flow reactors is maintained at 17-22 bar with the aid of back pressure regulators. The residence time is preferably maintained in the range of 1-4 hours. During the course of the reaction ammonia gets consumed, so intermittent shots of NH3 are injected into the reactor at suitable locations during the reaction. The continuous flow processing of AADMA is evaluated by conducting the experiments with various amounts of CADMA, aq. ammonia, at different temperatures, under different operating pressures, and also by varying the amount of intermittently added gaseous NH3 and the number of intermittent additions for various residence times. In each case, the conversion percentage, selectivity percentage and percentage of dimer formed are estimated by performing the GC and GC-MS analysis. The results obtained are given in Tables 1 to 5 along with the most preferred conditions for obtaining AADMA with highest purity and maximum yield.
Table 1 Results of Continuous Flow process of AADMA
Sl. No. Flow rate of CADMA (ml/Hour) Flow rate of Aq. Ammonia
(ml/Hour) No. of Intermittent NH3 addition Total residence time (hrs) Process Temp. (⁰C) Pressure (bar) Results
Conversion (%) Selectivity (%) Dimer (%)
1 26 90 - 1 105 15 93.2 80.1 18.3
2 34 253 2 1.5 120 15 98.9 81.8 18.4
3 54 190 3 1.5 110 15 94.6 85.0 13.2
4 52 380 4 2 115 15 95.6 81.6 13.0
5 54 396 2 1.5 125 16.5 96.1 79.1 19.1
6 54 190 3 1.5 110 15 94.6 85.2 13.2

Table 2 Preferred reaction conditions arrived at for Continuous flow process of AADMA
Parameters Conditions
Pressure >=16 bar
No. of Intermittent NH3 addition >2
Residence Time (hours) 1.5-2.5
Temperature (⁰C) >=110
Dimer (%) (Major Impurity) 13-19%
Conversion (%) >98%
Selectivity (%) 80-85%

Table 3 Results obtained for intermittent gaseous NH3 addition in continuous flow mode
Parameters Conditions
NH3 Mole Ratio >=25 NH3 Mole Ratio < 25
Residence Time(hours) 2.5 4
Pressure 21-22 bar 11 bar
AADMA (%) (Product) 81-88% 35.7-52.5 %
CADMA (%) (Starting Material) <1% 13.4-24.3 %
Dimer (%) (Major Impurity) 10-15% 21.8-38 %
Conversion (%) >99% 61-75 %

Table 4 Results obtained in continuous flow mode at various Pressures
Parameters Autogenous pressure
21 bar 17 bar 11 bar
Reaction Time (hours) 2.5 4 4
AADMA (%) (Product) 84.1% 80.8% 53.8%
CADMA (%) (Starting Material) <1% 0.6% 38.9%
Dimer (%) (Major Impurity) 15.2% 15.8% 6.9%
Conversion (%) >99% >99% 61.1%

Table 5 Preferred continuous flow reaction conditions
Parameters Value
Pressure 17-22 bar (excess gaseous ammonia pressure)
Residence Time (hours) 2.5-4
Temperature (⁰C) 110-130
NH3 mole ratio >25
AADMA (%) (Product) 81-84%
CADMA (%) (Starting Material) <1%
Dimer (%) (Major Impurity) 13-15%
Conversion (%) >99%

[035] From the above experimental results obtained for processing AADMA in a continuous flow reactor, it is evident that the selectivity towards AADMA and reduction in residence time was observed in presence of gaseous ammonia during the reaction conducted at elevated pressures of 21-22 bar and at temperatures of 115-125 ⁰C. The higher the mole ratio of aqueous ammonia w.r.t CADMA, the greater will be the selectivity towards AADMA and lesser will be the dimer formation. Based on these studies, preferred reaction conditions with high conversion and selectivity and reduced time with less dimer formation are arrived at.
[036] In order to establish the efficacy and suitability of continuous flow processing of AADMA over the Batch processes , experiments are conducted in batch mode under similar conditions of temperature and pressure for manufacturing AADMA and the results are compared.
EXPERIMENTAL PROCEDURES OF BATCH REACTION
[037] A calculated quantity of CADMA and aq. ammonia solution are charged into an autoclave reactor. The reactor was sealed, and ammonia gas was passed through the mass via a dip tube for a short period of time. The reaction mixture was allowed to stir thoroughly, and the temperature of the reaction mixture is maintained at 110-125 ⁰C through an external heating utility. Upon reaching this temperature the system generates a constant pressure of 17-21 bar. The reaction was allowed to continue for 2-4 hours, and the organic layer was extracted with NaOH and later distilled to obtain pure AADMA (~99%). The results are given in the following tables 6-8.
COMPARATIVE STUDY OF PARAMETERS (BATCH)
Table 6 Effect of extra NH3 addition in Batch process
Compound Parameters
With Extra Ammonia Without Extra Ammonia
AADMA (%) (Product) 83% 52.75%
CADMA (%) (Starting Material) <1% 13%
Dimer (%) (Major Impurity) 15% 21%
Conversion (%) >99% 61%

Table 7 Effect of Temperature on Batch process
Compound Parameters
Temperature 125 ⁰C Temperature 115 ⁰C
Reaction Time (hours) 2.5 4
AADMA (%) (Product) 84.09% 83%
CADMA (%) (Starting Material) <1% <1%
Dimer (%) (Major Impurity) 15.21% 15%
Conversion (%) >99% >99%

Table 8 Effect of Pressure on Batch process
Compound Parameters
21 bar 17 bar 11 bar
Reaction Time (hours) 2.5 4 4
AADMA (%) (Product) 84.09% 80.82% 53.76
CADMA (%) (Starting Material) <1% 0.62% 38.93
Dimer (%) (Major Impurity) 15.21% 15.8% 6.97
Conversion (%) >99% >99% 61.07

ANALYSIS OF NOVELTY AND INVENTIVE STEP OF THE INSTANT INVENTION
[038] The instant invention of continuous manufacturing of aminoacetaldehyde dimethylacetal in a flow reactor in the absence of a catalyst is novel in the light of the prior art. The inventiveness of the invention lies in arriving at a continuous flow process for obtaining aminoacetaldehyde dimethyl acetal by way of treating chloroacetaldehyde dimethyl acetal with aqueous ammonia solution along with intermittent additions of gaseous ammonia, which improved the conversion percentage, drastically reduced the impurity quantity in the final product, and reduced residence time. The inventiveness of the instant invention is further evident from the fact that it reduces operational costs due to the reduction in residence time and also reduces downstream processing as the process is devoid of a catalyst. The instant invention further offers a cost-effective process for obtaining AADMA from CADMA compared to the existing processes.
INDUSTRIAL APPLICABILITY AND UTILITY ASPECT OF THE INSTANT INVENTION
[039] The instant invention of continuous manufacturing of aminoacetaldehyde dimethyl acetal in a flow reactor offers a cost-effective method of obtaining the said compound which has extensive application and utility as a drug-intermediate, precursor, prodrug in pharmaceutical industry.
[040] Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for designing other products without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the claims are not to be limited to the specific examples depicted herein. For example, the features of one example disclosed above can be used with the features of another example.
[041] Furthermore, various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept. For example, the geometric configurations disclosed herein may be altered depending upon the application, as may be the material selection for the components. Thus, the details of these components as set forth in the above-described examples, should not limit the scope of the claims.
[042] The exemplary embodiments of the instant invention can be realized with the help of the following examples.
CONTINUOUS PROCESS IN A FLOW REACTOR
EXAMPLE 1
[043] CADMA and >25% aqueous ammonia was pumped into flow reactor at flow rates of 26ml/hour and 190 ml/hour. The utility temperature was set at 110 ⁰C and pressure inside the reactor was maintained at 15 bar using a back pressure regulator. The residence time was maintained for 1 hour and 415g of reaction mass collected, was taken for extraction using NaOH pellets. 16.15g of organic layer was distilled and ~99% pure AADMA was obtained.
EXAMPLE 2
[044] CADMA and >25% aqueous ammonia was pumped into flow reactor at flow rates of 34 ml/hour and 253 ml/hour. The utility temperature was set at 130 ⁰C and pressure inside the reactor was maintained at 15-16 bar using a back pressure regulator. Gaseous ammonia was added intermittently, 2 times during the reaction. The residence time was maintained for 1.5 hours and 204g of reaction mass collected, was taken for extraction using 110g NaOH pellets. The organic layer was distilled and ~99% pure AADMA was obtained.
EXAMPLE 3
[045] CADMA and >25% aqueous ammonia was pumped into flow reactor at flow rates of 54 ml/hour and 190 ml/hour. The utility temperature was set at 110 ⁰C and pressure inside the reactor was maintained at 15-16 bar using a back pressure regulator. Gaseous ammonia was added intermittently, 3 times during the reaction. The residence time was maintained for 1.5 hours, and 415 g of reaction mass collected was taken for extraction using NaOH pellets. The organic layer was distilled and ~99% pure AADMA was obtained.
COMPARATIVE EXAMPLES OF BATCH PROCESSING OF AADMA
EXAMPLE-4
[046] 54.7g of CADMA and 333g of aqueous ammonia (25% ) were added to autoclave. The pressure inside the autoclave was maintained between 11-13 bar. The utility was set in a range of 105 ⁰C and the reaction was carried out for 4 hours. The 554.94g of reaction mass was collected and NaOH pellets were added to the reaction mass to extract organic layer. Organic layer was distilled to obtained ~99% pure AADMA.
EXAMPLE-5
[047] 84.5g of CADMA and 524.18g of aqueous ammonia (25%)were added to autoclave and was pressurized with gaseous ammonia. The pressure inside the autoclave was maintained at 21-22 bar with utility temperature set at 130 ⁰C and the reaction was carried out for 2.5 hours. The 554.94g of reaction mass was collected and NaOH pellets were added to the reaction mass to extract the organic layer. Organic layer was distilled to obtained ~99% pure AADMA.
EXAMPLE-6
[048] 85g of CADMA and 518g of aqueous ammonia (25%) were added to autoclave and was pressurized with gaseous ammonia. The pressure inside the autoclave was maintained at 17 bar with utility set at 110⁰C and the reaction was carried out for 5 hours. Samples were drawn at regular interval of 1 hour to observe conversion rate (Table 4.2.5). The 656g of reaction mass was collected and NaOH pellets were added to the reaction mass to extract the organic layer. Organic layer was distilled to obtained ~99% pure AADMA.
EXAMPLE-7
[049] 42g CADMA and aqueous ammonia (25%) were added to autoclave and was pressurized with gaseous ammonia. The pressure inside the autoclave was maintained at 21 bar with utility set at 125⁰C and the reaction was carried out for 4 hours. 610 g of reaction mass was collected and NaOH pellets were added to the reaction mass to extract the organic layer. Organic layer was distilled to obtained ~99% pure AADMA.
, Claims:I/We Claim:
1. A continuous process for the production of 2-amino-1,1-dimethoxyethane or aminoacetaldehyde dimethylacetal from chloroacetaldehyde dimethylacetal, and aqueous ammonia comprising 25% to >25 wt.% of dissolved NH3, in the flow ratio of 1: 7 to 1:14, at a temperature of 100OC -150OC, under operating pressures of 15 to >15bars, with a total residence time of 1-4 hours, with intermittent addition of gaseous ammonia in the absence of a catalyst, in a flow reactor.
2. The continuous process as claimed in claim1 wherein the aqueous ammonia contains NH3 in the range of 25 to 50% by wt% dissolved NH3 in water.
3. The continuous process as claimed in claim 1 wherein the intermittent addition of gaseous ammonia is at intervals of 15, 30, 45 minutes during the residence time.
4. The continuous process as claimed in claim 1 is done in a flow reactor with a provision for internal mixing.
5. The continuous process as claimed in claim 1 wherein the operating pressures are from 15-50bars.