Improved process for amino alcohol synthesis from hydroxyacetone

Abstract

The present disclosure relates to a process of preparation of 2-amino alcohol of formula I comprising: i) reacting 2-hydroxyketone or 2-hydroxyaldehyde of formula II in presence of an aminating agent and a solvent under condition to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of a metal catalyst and H2 under condition to obtain 2-amino alcohol of Formula I.

Description

[0001] IMPROVED PROCESS FOR AMINO ALCOHOL SYNTHESIS FROM HYDROXYACETONE

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates generally to the field of chemical synthesis. More particularly, the present disclosure provides an improved process for synthesis of 2-amino alcohol from 2 -hydroxyketone or 2-hydroxyaldehyde.

[0004] BACKGROUND OF THE INVENTION

[0005] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0006] US3448153 discloses a reductive amination of 2 -keto- 1 -alkanols produces 2-amino- 1 -alkanols. The products prepared in accordance with the invention are emulsifying agents that find application in the preparation of floor polishes, shoe polishes, automobile cleansers-polishes, emulsion paste waxes, and substituted piperazines by means of a cyclic reductive amination reaction. Further, alkylene oxides may be reacted with the amino-alkanols to yield nitrogen-containing polyether polyols useful in the preparation of polyurethanes.

[0007] US3953512 discloses a method of preparation of 2-aminobutanol from readily available raw materials. The method of this invention is based on the reaction between 1,2-epoxybutane or isomeric butylene halo genehydrines with ammonia.

[0008] US4151204 discloses a process for preparing amino alcohol, which comprises reacting a polyhydric alcohol containing at least one primary alcoholic hydroxyl group and at least one secondary alcoholic hydroxyl group with ammonia in the presence of specified hydrogenation catalyst thereby to aminate the secondary alcoholic hydroxyl group of the polyhydric alcohol selectively. This process is carried out at high temperature.

[0009] US 5053545 discloses a method of preparing an amino alcohol in which R3 is H or lower alkyl which comprises reacting in a single step a halonitroalcohol with hydrogen in the presence of methanol, ammonia and a hydrogenation catalyst, treating the resulting acid salt of the amino alcohol with an alkali material, and recovering the resultant amino alcohol. Example 3 and Example 5 showed 28 % and 29 % ammonia solution respectively which indicates that ammonia is in aqueous solution.

[0010] Tregner et al., [Chem. Biochem. Eng., 2017, 31 (4), 455-470] discloses one-step reductive amination of l-hydroxy-2-propanone (acetol) with ammonia to 2-aminopropanol (2-APOL) over commercial nickel and copper catalysts has been studied in the continuous fixed-bed reactor at the temperature from 130 to 220 °C and different molar ratios of reactants. It was found that the optimal molar ratios of fE / acctol and H2 / NH3 regarding the selectivity of 2-APOL were 25 and 1, respectively. The highest selectivity of approx. 45 % to desired 2-APOL at total conversion of acetol was achieved in the presence of the nickel catalyst. In this document, higher temperature 130 to 220 °C is used and the selectivity is also reported upto 45% only.

[0011] Chakraborti et al. discloses that silica gel (60-120 mesh) efficiently catalyses the opening of epoxide rings by amines at room temperature under solvent-free conditions providing an easy method for the synthesis of 2-amino alcohols. This document reports ring opening of epoxides, works mostly for aromatic compounds, and separation of regioisomers is difficult.

[0012] EP 0534553A1 discloses a method for the preparation of an a, a- di substituted a-amino alcohol from the corresponding amide with the aid of sodium in the presence of an alcohol as solvent. This document discloses use of sodium in methanol in the reaction, sodium metal is highly exothermic and when exposed to atmosphere immediately catches fire, handling difficulty, and extremely reactive.

[0013] US 4,105,669 discloses reaction of l-hydroxy-2-ketones of the general formula R— CO— CH2 OH, where R is a short alkyl, with ammonia gives a new compound which on hydrogenation gives 2-amino- 1 -alcohols; the yield can be improved by carrying out the hydrogenation in the presence of ammonia. This process is carried out at high pressure.

[0014] 1,2- Aminoalcohol synthesis by C-C coupling have also reported in the literature which have much more expensive reagents, reaction time is 48 hrs and temperature is in the range of -90 °C to -78 °C. It is reported that aminoalcohol is synthesized by Hydroxyacetone reacting with 25 / 30% aqueous ammonia to form 2-imino-l propanol (imine) which in turn undergoes hydrogenation using a suitable catalyst. Traditional methods involving the reaction of hydroxyacetone with 25 / 30% aqueous ammonia suffer from issues related to energy consumption during isolation of final product and temperature control during storage, recyclability issues for aqueous ammonia and water related impurities formed in this reaction which causes additional distillation requirement for product formation, etc. Higher pressure requirement for hydrogenation step, and in cases where ammonia gas was used at high pressures (100 - 300 bar) or high temperatures were required, either for the step of amination or in the next step of hydrogenation.

[0015] In cases where aqueous ammonia is replaced by gaseous ammonia, the reaction necessitates extremely high pressures. Similarly, the subsequent hydrogenation step also requires exceptionally elevated pressure levels for synthesizing amino alcohols.

[0016] Hence, there is still a need to develop an effective and improved method for the synthesis of amino alcohol.

[0017] OBJECTIVES OF THE INVENTION

[0018] The primary object of the present invention is to develop an improved process for synthesis of 2-amino alcohol from 2-hydroxyketone or 2-hydroxyaldehyde.

[0019] Another object of the present invention is to provide a process for synthesis of amino alcohol at moderate temperature and pressure.

[0020] Still another object of the present invention is to provide a process for synthesis of amino alcohol with higher yield.

[0021] Yet another object of the present invention is to provide a cost effective and large-scale synthesis of amino alcohol.

[0022] SUMMARY OF THE INVENTION

[0023] This summary is provided to introduce in a simplified form of selection of concepts that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the subject matter, nor is it intended to be used as an aid in determine the subject matter’s scope.

[0024] Aspect of the present disclosure is to provide a process of preparation of 2-amino alcohol of formula I comprising: i) reacting 15 to 20 %w / w of 2 -hydroxyketone or 2-hydroxyaldehyde of formula II in presence of 12 to 16 %w / w of an aminating agent and 65 to 75 %w / w of a solvent under condition to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of 15-25% w / w of a metal catalyst with respect to formula II and continuous 10-25 bar H2 under condition to obtain 2-amino alcohol of Formula I.

[0025] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

[0026] DETAILED DESCRIPTION OF THE INVENTION

[0027] The following is a detailed description of embodiments of the disclosure. The embodiments are to clearly communicate the disclosure. However, the of detail offered is not intended to limit the anticipated variations of embodiments; to cover all modifications, equivalents, and alternatives fall within the spirit and scope of the present disclosure.

[0028] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0029] A reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0030] As used in the description herein that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[0031] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”

[0032] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

[0033] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e. g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention.

[0034] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.

[0035] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.

[0036] It should also be appreciated that the present disclosure can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.

[0037] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

[0038] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

[0039] Embodiments of the present disclosure relate generally to the field of chemical synthesis. More particularly, the present disclosure provides a novel, easy, efficient and improved process for synthesis of 2-amino alcohol from 2-hydroxyketone or 2-hydroxyaldehyde.

[0040] The present disclosure provides a novel, easy and more efficient process as described above, with advantages / improved effects like avoiding aqueous or water based materials (hence water impurities is completely avoided), uses simple and lower alcohols like MeOH, EtOH, IPA for the effective solubilization of materials, higher yields upto 85%, preferably 84%, more preferably 83%, most preferably 82 %, lower temperature range (70-80 °C), low pressure requirement (max upto 25 bars), and the like.

[0041] Aminoalcohols are used as buffers. They are good solubalizers of oil and fat and so they are used to neutralize fatty acids and sulfonic acid -based surfactants. Some racemic mixtures of aminoalcohols are used in manufacturing metal working fluids, automobile cleaners-polishes waterborne coatings, personal care products and emulsion paste waxes. It is also an intermediate in the synthesis of a variety of pharmaceutical drugs. These compounds are also utilized in preparation of substituted piperazines by means of a cyclic reductive amination reaction. Even further alkylene oxides maybe reacted with aminoalcohols to yield nitrogen containing poly ether polyols useful in the preparation of polyurethanes.

[0042] An embodiment of the present disclosure provides a process of preparation of 2-amino alcohol of formula I comprising: i) reacting 15 to 20 %w / w of 2-hydroxyketone or 2-hydroxyaldehyde of formula II in presence of 12 to 16 %w / w of an aminating agent and 65 to 75 %w / w of a solvent under condition to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of 15-25% w / w of a metal catalyst with respect to formula II and continuous 10-25 bar H2 under condition to obtain 2-amino alcohol of Formula I.

[0043] In a preferred embodiment, the process of preparation of 2-amino alcohol of formula I comprising: i) reacting 17%w / w of 2-hydroxyketone or 2 -hydroxy aldehyde of formula II in presence of 14 %w / w of an aminating agent and 69 %w / w of a solvent under condition to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of a 15-25% w / w of metal catalyst with respect to formula II and continuous 10-25 bar H2 under condition to obtain 2-amino alcohol of Formula I.

[0044] In an embodiment, the process of preparation of 2-amino alcohol of formula I comprising: i) reacting 25g of 2-hydroxyketone or 2 -hydroxy aldehyde of formula II in presence of 20.07g (3.5eq) of an aminating agent and 100g of a solvent under condition to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of a 15-25% w / w of metal catalyst with respect to formula II and continuous 10-25 bar H2 under condition to obtain 2-amino alcohol of Formula I.

[0045] In an embodiment, the 2-hydroxyketone is selected from hydroxy acetone, 1 -hydroxy-2-propanone, 4-hydroxy-2-butanone, 1 -hydroxy-2-butanol,

[0046] 3-hydroxy-2-pentanone, 2-hydroxy-3-pentanone, 5-hydroxyhexan-2-one,

[0047] 3-hydroxyhexane-2, 5-dione, 4-hydroxyhexan-3-one, and the like.

[0048] In an embodiment, the 2-hydroxyaldehyde is selected from, 2-Hydroxy-2-methylpropanal, 2 -hydroxybutanal, 3-Hydroxybutanal, 3-hydroxy-2-methylpentanal, and the like.

[0049] In an embodiment, the aminating agent is selected from ammonia gas or gaseous primary amines. The aminating agent is added in the range of 2 to 5 eq., preferably in the range of 3 to 4 eq.

[0050] In an embodiment, the solvent is selected from a group consisting of C1-C4 alcohol. Preferably, the solvent is methanol, ethanol, isopropyl alcohol and combination thereof. More preferably, the solvent is methanol.

[0051] In an embodiment, the 2-hydroxyketone or 2-hydroxyaldehyde of formula II and solvent are added in a ratio in the range of 1:5 to 5:1. Preferably the ratio is 1:4.

[0052] In an embodiment, the condition in step i) includes temperature in the range of 0 to 40 °C for time period in the range of 0.5 to 2 hrs.

[0053] In an embodiment, the imine intermediate with solvent are added in a ratio in the range of 1:5 to 5:1. Preferably the ratio is 1:4.

[0054] In an embodiment, the condition in step ii) includes pressure in the range of 15-25 bars and temperature in the range of 70-80 °C for a time period in the range of 6 to 10 hrs.

[0055] In an embodiment, the metal catalyst is selected from a Nickel catalyst. The amount of metal catalyst is added in the range of 15 % to 25 % w / w with respect to 2-hydroxyketone. Preferably, the amount of metal catalyst is 20 % w / w with respect to 2-hydroxyketone.

[0056] In an embodiment, agitation is carried out in the range of 800-1200 rpm. Preferably, agitation in the range of 900-1100 rpm. More preferably, agitation in the range of 1000-1050 rpm.

[0057] In an embodiment, the process of preparation of 2-amino alcohol of formula I having the steps of: i) reacting 2-hydroxyketone or 2 -hydroxy aldehyde of formula II in presence of ammonia gas or gaseous primary amines as aminating agent and C1-C4 alcohol as solvent at temperature in the range of 0 to 40 °C for time period in the range of 0.5 to 2 hrs to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate in presence of Ni metal catalyst and H2 at a pressure in the range of 15-25 bars and at temperature in the range of 70-80 °C for time period in the range of 8 hours to obtain 2-amino alcohol of formula I as shown in the below synthetic scheme. The yield of the obtained 2-amino alcohol is 75-85 %, preferably 75-84%, more preferably 75-83%, most preferably 75-82%. wherein, Ri is selected from H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl; and wherein, R2 is selected from H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl; and

[0058] Scheme 1: Synthetic scheme for the preparation of 2-amino alcohol of formula I.

[0059] In an embodiment, the resulting 2-amino alcohol is selected from but not limited to 2-amino-propanol, 2-Amino-2-methyl-l -propanol, 2-Amino-l -butanol, 2-Amino-3-methyl-l-butanol

[0060] Amino alcohols are versatile compounds with widespread industrial applications. It serves as a key ingredient in the formulation of detergents and cleaning products, owing to its effective surfactant properties. Additionally, it acts as a corrosion inhibitor in metalworking fluids, ensuring the longevity of machinery by protecting metal surfaces from degradation. This compound also plays a vital role as an intermediate in the synthesis of pharmaceuticals, dyes, and other organic compounds, contributing significantly to the production of valuable materials. Furthermore, it functions as a solvent in various chemical processes and formulations and is utilized as an antiseptic agent in specific applications due to its antimicrobial properties. Its diverse uses underline its importance in different industrial sectors, emphasizing the need for understanding its properties for safe and efficient application.

[0061] EXAMPLES

[0062] Materials and Procurement details:

[0063] Example 1

[0064] (A) Synthesis of iminoalcohols

[0065] Imines are formed by condensation of carbonyl compounds such as aldehydes or ketones with an amine. Under specific conditions (0 - KFC), hydroxyacetone reacts with ammonia to produce 2-imino-l -propanol. This intermediate is vital for synthesizing 2-amino-propanol, it's highly unstable and susceptible to oxidation. i) Small Scale is of 2-imino-l

[0066] Using 100% Gas Ammonia as Reagent

[0067] Reactants

[0068] I. Acetol: 25gm

[0069] II. Gas Ammonia (100%) (3.5eq): 20.07 gm

[0070] Solvent

[0071] III. Methanol (1:4 with respect to acetol): 100 gm

[0072] • Acetol and methanol were fed into the 300 mL autoclave.

[0073] • During the introduction of gaseous ammonia, the autoclave was carefully placed on a weighing balance, enabling the precise metering of the ammonia quantity to be fed into the reaction mixture.

[0074] • The exothermic nature of the reaction was diligently observed, documenting both temperature and pressure fluctuations in real-time.

[0075] • Agitation was initiated at a rapid speed of 1000 rpm to facilitate efficient mixing of the reactants, promoting homogeneity and maximizing the reaction surface area for enhanced reactivity.

[0076] • To maintain the reaction temperature at a specific level, a well-regulated mixture of ice and water was employed, creating a controlled cooling environment around the autoclave. This technique ensured the reaction temperature remained stable around 10°C, optimizing the reaction conditions.

[0077] • The reaction mixture was consistently subjected to continuous stirring for a precisely defined duration of one hour.

[0078] • The resulting imine product, formed as a result of the reaction, was harvested and utilized for subsequent hydrogenation processes, contributing to the synthesis of desired chemical compounds in the ongoing scientific investigation. (ii) Large Scale Synthesis of 2-imino-l propanol

[0079] Reactants

[0080] I. Acetol: 500 gm

[0081] II. Gas Ammonia (100%) (3.6eq): 416 gm

[0082] Solvent

[0083] III. Methanol (1:4 with respect to acetol): 2000 gm

[0084] • The initial reactant i.e., Acetol and solvent Methanol were feed into the autoclave.

[0085] • Agitation was set to 1000-1050 rpm.

[0086] • Temperature was maintained around 10 °C with the help of external cooling utility. The temperature of cooling utility was set to 0 °C.

[0087] • Gaseous ammonia cylinder was used to feed the ammonia.

[0088] • The initial weight of ammonia cylinder was noted.

[0089] • The cylinder was placed on weighing balance to observe the weight of ammonia which was being fed to the autoclave.

[0090] • The total ammonia was fed in such a way that it should be completed in an hour i.e., ammonia was added slowly for better conversion of acetol to imine.

[0091] • As the reaction was exothermic in nature the temperature was controlled below 12 °C.

[0092] • Once the addition gets completed, the reaction maintained for 2 hour at around 10 °C.

[0093] • After the addition, cylinder weight is measured to cross check net amount of ammonia added to the autoclave.

[0094] (B) Synthesis of aminoalcohols

[0095] Hydrogenation is carried out of imino alcohols to amino alcohols using hydrogen gas in the presence of nickel catalyst using alcohols such as methanol, ethanol and isopropyl alcohols as solvent.

[0096] (i) Small Scale Synthesis of 2 aminopropanol:

[0097] Reactants I. Imine synthesized in gas ammonia: 25gm

[0098] II. Hydrogen pressure: 15 bar

[0099] Solvent

[0100] III. Methanol (1:4 with respect to imine) - lOOgm

[0101] Catalyst

[0102] IV. Skeletal Nickel Catalyst (20% w / w with respect to 2-hydroxyketone) - 5 gm

[0103] • A 300 mL PARR autoclave was charged with a mixture comprising the synthesized imine, methanol, and an appropriate quantity of catalyst, ensuring accurate proportions.

[0104] • To establish an oxygen-free environment within the autoclave, it undergoes a thorough purging process using hydrogen gas (H2).

[0105] • Employing a mass flow controller (MFC), a precisely controlled reaction pressure of 8 bar was applied to the autoclave, and the system was heated to an initial temperature of 70°C.

[0106] • Upon reaching the temperature and pressure conditions, the temperature was finely adjusted to the required value of 75°C, while the pressure was increased to 15 bar.

[0107] • The established reaction parameters, including temperature and pressure, were meticulously maintained for a duration of 8 hours. A representative sample may be extracted after 5 hours to monitor the progress of the reaction.

[0108] • Upon completion of the designated reaction time, the reaction mass was systematically cooled down using appropriate cooling methods.

[0109] • As the reaction mass gradually cools to ambient temperature, the internal pressure was gradually released from the autoclave, ensuring a safe depressurization process.

[0110] • Subsequently, the reaction mass was carefully transferred from the autoclave to a separate vessel for further analysis and processing.

[0111] (ii) Large Scale Synthesis of 2 aminopropanol: The stoichiometry was as follows:

[0112] Reactants

[0113] I. Imine synthesized in gas ammonia: 916gm

[0114] II. Hydrogen pressure: 15 bar

[0115] Solvent

[0116] III. Methanol (1:4 with respect to imine) - 2000 gm

[0117] Catalyst

[0118] IV. Skeletal Nickel Catalyst (20% w / w with respect to 2-hydroxyketone) - 100 gm

[0119] This was the standard procedure followed. However, various permutation and combinations were applied in order to produce maximum 2AP selectivity. These are mentioned in the table 1 below.

[0120] (C) Characterization Data:

[0121] (i) Imino alcohols Synthesis:

[0122] The invention discloses a gas chromatography method for analyzing 2-aminopropanol using an Agilent Technologies Inc. HP-5 column and flame ionization detector. The column, with dimensions 30m x 0.32 mm x 0.25 micron, operates in a temperature range of -60 to 325°C. The injector, set at 250°C, employs a 150:1 split ratio and 4.7282 PSI pressure. The oven, with an equilibrium time of 0.25 min, reaches a maximum temperature of 325°C. The method, with precise temperature profiles and flow rates, ensures accurate quantification of 2-aminopropanol within a 24-minute run time.

[0123] Standards for imino alcohols do not exist, as the imine group is unstable. Therefore for characterization of imino alcohols by Gas Chromatography on an HP-5 column could only be done, by checking area percentage.

[0124] However, confirmation of imino alcohol synthesis was done by IR, NMR and GC-MS. Characterization of imino alcohols by Gas Chromatography is given in Table 1.

[0125] Table 1 : Characterization of imino alcohols by Gas Chromatography.

[0126] (ii) Scale-up Synthesis Imino alcohols:

[0127] Results of scale -up synthesis of imino alcohols are given in Table 2.

[0128] Table 2: Scale-up results of imino alcohols. (D) Selectivity

[0129] (i) Small Scale 2AP synthesis:

[0130] Selectivity of small scale 2AP synthesis is given in Table 3. Under optimal reaction conditions, specifically at a hydrogen pressure of 15 bar and utilizing 20% w / w with respect to 2-hydroxyketone catalyst at 75 °C, the selectivity exhibited a range between 73% and 75%. Enhanced selectivity within the range of 78% to 80% was achievable; however, this necessitated either an augmented catalyst quantity or an elevated pressure by 5 bar. Notably, imino alcohol synthesis conducted under ambient temperature conditions, in contrast to cold conditions, yielded a selectivity of 78.75%. Furthermore, elevating the hydrogenation reaction temperature to 80°C resulted in an increased selectivity of 78.1%. Table 3: Selectivity of 2AP

[0131] (ii) Large Scale

[0132] Selectivity of large scale 2AP synthesis is given in Table 4. Upon scaling up the synthesis to a 5L capacity, the selectivity experienced a notable enhancement up to 82%, while adhering to the same reaction conditions.

[0133] Table 4: Selectivity of large scale 2AP synthesis.

[0134] ADVANTAGES OF THE INVENTION i) Elimination of Temperature Control Requirement:

[0135] Unlike the prior art, the present method negates the need for maintaining aqueous ammonia at low temperatures (-2 to 5 °C) during the reaction, enabling a more streamlined and cost-effective large-scale synthesis. ii) Energy Efficiency:

[0136] The innovative process eliminates the energy-intensive distillation of water to recover final product, reducing overall energy consumption in the synthesis of 2-aminopropanol. iii) Simplified Protocol:

[0137] By employing gaseous ammonia and methanol as the solvent, the synthesis protocol is streamlined, by eliminating the need for exceedingly high pressures and temperatures. This optimized method enhances accessibility for industrial applications. iv) Recyclability:

[0138] In addition to the catalyst, the recovered methanol is also recyclable, ensuring sustainability. Methanol analysis enables precise ammonia concentration measurement and facilitates ammonia replenishment, enhancing operational efficiency and resource utilization.

Claims

WE CLAIM:

1. A process of preparation of 2-amino alcohol of formula I comprising: i) reacting 15 to 20 %w / w of 2-hydroxyketone or 2 -hydroxy aldehyde of formula II in presence of 12 to 16 %w / w of an aminating agent and 65 to 75 %w / w of a solvent at a temperature in the range of 0 to 40 °C for time period in the range of 0.5 to 2 hrs to obtain imine intermediate; and ii) processing by hydrogenation the imine intermediate obtained at step i) in presence of 15-25% w / w of a metal catalyst with respect to formula II and continuous 10-25 bar H2 and temperature in the range of 70-80 °C for a time period in the range of 6 to 10 hrs to obtain 2-amino alcohol of Formula I in 75-85 % yield.wherein, Ri is selected from H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl; and wherein, R2 is selected from H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec -butyl, tert-butyl, pentyl, and hexyl.

2. The process as claimed in claim 1, wherein the aminating agent is selected from ammonia gas or gaseous primary amines.

3. The process as claimed in claim 2, wherein the aminating agent is added in an amount in the range of 2 to 5 equivalents of 2-hydroxyketone or 2-hydroxyaldehyde.

4. The process as claimed in claim 1, wherein the solvent is selected from a group consisting of C1-C4 alcohol.

5. The process as claimed in claim 4, wherein the solvent is methanol, ethanol, isopropyl alcohol and combination thereof.

6. The process as claimed in claim 4, wherein the 2 -hydroxyketone or 2-hydroxyaldehyde of formula II and solvent are added in a ratio in the range of 1:5 to 5:

1.

7. The process as claimed in claim 4, wherein the imine intermediate and solvent are added in a ratio in the range of 1 :5 to 5: 1.

8. The process as claimed in claim 1, wherein the metal catalyst is a Nickel catalyst used in an amount of 15 % to 25 % w / w with respect to 2-hydroxyketone.

9. The process as claimed in claim 1, wherein the agitation is carried out in the range of 800-1200 rpm.

10. The process as claimed in claim 1, wherein the 2-amino alcohol is selected from 2-imino-l propanol or 2 aminopropanol.

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