FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
"METHOD FOR CONTINUOUS PRODUCTION OF METHYL PENTENONE"
2. APPLICANT
1. NAME : PRIVI ORGANICS LIMITED
2. NATIONALITY: INDIAN COMPANY
3. ADDRESS : PRIVI HOUSE, A-71, TTC,
THANE BELAPUR ROAD,
NEAR KOPER KHAIRANE RLY. STATION,
NAVI MUMBAI-400709 MAHARASHTRA, INDIA

The following specification particularly describes the invention and the manner in which is to be performed.

FIELD OF INVENTION
The present invention discloses method for continuous production of methyl pentenone (3-Methyl 3-Pente2none) from acetaldehyde and methyl ethyl ketone (MEK). In the present method, heterogeneous catalyst is adopted to use in such manner which gives better yield and less byproduct formation than conventional homogeneous catalysis. The method of present invention involves contacting mixture of acetaldehyde and MEK with catalyst with profile of temperature range in reactor between 60°C to 100°C. In the present method, it is selectively adopted to maintain residence time of reactants in reactor, in the range between 30 to 180 minutes.
BACKGROUND OF THE INVENTION
Methyl pentenone is an intermediate in the reaction to produce Iso E Super, which is a widely used synthetic aroma chemical. Generally, aldol condensation reactions are acid as well as base catalyzed reactions. Conventional process for synthesis of methyl pentenone involves a batch homogeneous reaction between acetaldehyde and MEK, catalyzed by sulphuric acid. This follows series of steps such as neutralization of crude reaction mixture, water wash and then distillation. Such conventional process produces large residue (polymerized product) after distillation. So a large number of effluents are coming out of this process.
EP1997796 discloses processes for cross aldol reactions using strongly basic, anionic, macroreticular polymeric resin with quaternary ammonium groups of the type -CH 2N + (CH 3 ) 3 as heterogeneous catalysts. It has been claimed that catalyst used therein is recyclable and the process can be repeated several times. But such reaction may run for several hours which is not desirable.
US 4301184 discloses process for synthesis of methyl pentenone in presence of zinc acetate as catalyst. In the process, metallic oxide or salt ( zinc acetate) is used for the production of alpha beta unsaturated ketone. Temperature used for reaction is 100°C to 250°C which required pressure reactor. It is stated that base used for reaction such as potassium hydroxide and zinc oxide, sodium hydroxide produce undesirable self condensate products. The yield obtained in this process is only 13%.

US 4005147 discloses process for the production of at least .alpha.,.beta.-unsaturated ketones which may also contain an alkyl group as a substituent and/or an endoalkylene group or an araliphatic hydrocarbon radical of seven to 15 carbon atoms or an aromatic hydrocarbon radical. It discloses role of zinc oxide in catalyst to convert aldehyde and ketone to alpha beta unsaturated ketone in liquid phase.
US 2549508, discloses process wherein aldehyde and ketone can be converted to alpha beta unsaturated ketone with high molecular mass species in gas phase at high temperature (500°C-1000°C) in presence of zinc oxide and zirconium oxide as catalyst. Such metal catalyst process with high temperature shows low conversation and lower yield and required high expenditure equipments to control hydrogen gas at high temperature. Also at such high temperature cracking processes take place which affect the life of catalyst and byproducts formation (polymerization or tar).
German patent No 1203243 discloses use of molybdenum oxide and magnesium oxide as caralyst for condensation of identatical or different aldehyde and/or ketone. The reaction is carried out in liquid phase and elevated temperature. The disclosed method describe yield of alpha beta unsaturated aldehyde with aldehyde are very good in perticulare condensation of butaraldehyde and 2-ethyl hexenal. But this process is not Suitable for aldehyde and ketone condensation to gate alpha beta unsaturated ketone, because of low conversion and yield.
Methyl pentenone is an intermediate in varies reactions to produces number of widely used synthetic aroma chemical. Generally, aldol condensation reactions is well known reaction in synthetic organic chemistry and catalyzed by acid as well as base catalyst. Kinetic and selectivity aspects of anion exchange resin catalyzed aldolization of formaldehyde and butaraldehyde is reported in applied catalysis A general 198, 2000, pp 207-211. 2-ethyl-3-hydroxy-2-hydroximethylpropanaI is the main product of aldolization and self condensation is the minor product.

BRIEF DESCRIPTION OF INVENTION
In invention, continuous method for production of methyl pentenone (3-Methyl 3-Pente2none) from acetaldehyde and methyl ethyl ketone (MEK) using a cation exchange resin as catalyst. Catalyst has acidic groups attached to the base matrix such as styrene divinyl benzene. The invention herein described combines the aldol condensation and dehydration into one step by resin catalyst, which can be used either in fixed bed and/or multi tubular or in CSTR; preferably fixed bed and /or plug flow reactor of catalyst may be used. In the present method, "aldol condensation" refers to the condensation of aldehydes, ketones and mixture of aldehydes and ketones with the simultaneous dehydration of the condensation product. When more than one molecular species of reactant is used, such as aldehyde-aldehyde, ketone-ketone, or an aldehyde with a ketone, then a mixture of products is usually produced. The proportion of each species of reactant used and their relative activities for the condensation reaction controls the product distribution.
Method for continuous production of methyl pentenone (3-Methyl 3-Pente2none) comprising steps of contacting acetaldehyde and methyl ethyl ketone (MEK) in ratio with a cation exchange resin at pressure 1.5 kg/cm2 to 10 kg/cm2 and at temperature 60°C to 100°C in a reactor to give in outlet of methyl pentenone, acetaldehyde, methyl ethyl ketone and water distillating outlet to get mixture of acetaldehyde and methyl ethyl ketone and water and distillating mixture of methyl pentenone and methyl ethyl ketone to get pure methyl pentenone. Acetaldehyde and methyl ethyl ketone (MEK) are taken in ratio of 3 5 to 80 % of acetaldehyde and 20 to 85 % of methyl ethyl ketone (MEK) by weight and contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is carried out in packed bed reactor in residence time of reactants in reactor, in the range between 30 to 180 minutes.
BRIEF DESCRIPTION OF DRAWINGS:
Drawing 1 shows Schematic diagram of packed bed reactor. Drawing 2 shows optimization of temperature for the present method.

STATEMENT OF INVENTION
Present invention particularly is related to method for continuous production of methyl pentenone (3-Methyl 3-Pente2none) comprising steps of (a) contacting acetaldehyde and methyl ethyl ketone (MEK) in ratio with a cation exchange resin at pressure 1.5 kg/cm to 10 kg/cm2 and at temperature 60°C to 100°C in a reactor to give in outlet of methyl pentenone, acetaldehyde, methyl ethyl ketone and water (b) distillating outlet from step (a) to get mixture of acetaldehyde and methyl ethyl ketone and water and (c) distillating mixture of methyl pentenone and methyl ethyl ketone to get pure methyl pentenone.
In Method of invention for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) wherein cation exchange resin is selected from strong cationic exchange resin and acetaldehyde and methyl ethyl ketone are mixed in mixing tank or mixed in online mixture with applied pressure/ with pressure in the range of 1.7 Kg/cm2 to 4 kg/cm2 in reactor.
In this Method, contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is preferably carried out in temperature range of 60 degree C to 85 degree C in packed bed reactor selected from jacketed packed bed reactor and multi tube reactor.
In Method of invention, packed bed reactor can be in form of multi tube reactor wherein temperature of reactor is maintained uniform by circulating hot water or steam flow rate in at multiple points.
Acetaldehyde and methyl ethyl ketone (MEK) are taken in ratio of 15 to 80 % of acetaldehyde and 20 to 85 % of methyl ethyl ketone (MEK) by weight and contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is carried out in packed bed reactor in residence time of reactants in reactor, in the range between 30 to 180 minutes.
In one of the embodiments of the invention continuous, production of methyl pentenone (3-Methyl 3-Penten-2one) is carried out by contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is carried with at least one reactant in liquid phase.

Pressure in the reactor is preferably selected in the range 2.5 kg/cm2 to 10 kg/cm2 such that at that pressure all components will remain in liquid phase based on concentration of reactants.
Parameter like residence time of reactants in reactor is preferably in the range between 50 to 150 minutes and judicially selected therein.
Thus outlet from step (a) is distilled out to get mixture of water and methyl ethyl ketone and Acetaldehyde is recycled to feed stream of reactor by removing water and further distilled to get pure methyl pentenone.
DESCRIPTION OF INVENTION
The present invention discloses method for continuous production of methyl pentenone (3-Methyl 3-Pente2none) from acetaldehyde and methyl ethyl ketone (MEK) using a cation exchange resin as catalyst. Catalyst has acidic groups attached to the base matrix such as styrene divinyl benzene. Catalyst is a macroporous solid material with catalytic activity over a substantial period of time. The invention herein described combines the aldol condensation and dehydration into one step by resin catalyst, which can be used either in fixed bed and/or multi tubular or in CSTR; preferably fixed bed and /or plug flow reactor of catalyst may be used.
In the present method, "aldol condensation" refers to the condensation of aldehydes, ketones and mixture of aldehydes and ketones with the simultaneous dehydration of the condensation product. When more than one molecular species of reactant is used, such as aldehyde-aldehyde, ketone-ketone, or an aldehyde with a ketone, then a mixture of products is usually produced. The proportion of each species of reactant used and their relative activities for the condensation reaction controls the product distribution.


Reaction scheme
MEK Acetaldehyde MPO
R,R1,R2 = CH3
Is it possible to say that R=H, R= any alkyl group (C1 to C6 carbon atom)
One of the embodiments of present invention is that method involves contacting mixture of acetaldehyde and MEK with catalyst with profile of temperature range in reactor between 60°C to 100°C. In the present method, it is selectively adopted to maintain residence time of reactants in reactor, in the range between 30 to 180 minutes.
In present invention, the catalyst used is cation exchange resin. The resin catalyst has a base matrix of styrene divinyl benzene and exchangeable acidic group attached to it. This resin catalyst is generally in acidic form; otherwise it can be brought to acidic form by treating with diluted acids, preferable sulphuric or hydrochloric acids; a process called catalyst regeneration or activation.
One of the embodiments of present invention, catalytic material is in the form of granules with particle size range from 0.4-1.2 mm, which is preferably packed in to a suitable reaction tube or chamber called catalytic column. The catalytic materia! thus acts as a fixed bed over which either the vapor or liquid carbonyl compounds may be passed in carrying out the condensation reaction.
It is observed that the catalytic material may also be used as a fluid bed type catalyst or in continuous stirred tank reactor (CSTR). But in that case, catalyst breakage due to shearing may be the problem at the large scale production. Suitable heating means may be used to maintain the desired operating temperature in the zone where the catalytic material is present.

The temperature at which the condensation reaction is conducted generally falls within the broad range of about 0° to 200°C or more with preferred temperature range from about 80°C to about 150°C. At the lower temperature, the rate of reaction is slow; with increasing temperature reaction rate increases but also increases the side product formation. In the present process, the reaction is carried out in the temperature range of 60°C to about 100°C, more preferably between temperatures of 60°C to 80°C. The pressure in the reactor is maintained at the values, such that at that pressure all components will remain in liquid phase at the desired temperature.
In the fixed bed of reaction, it is also desirable to remove the product from the proximity of the catalyst to avoid further polymerization of the product. Fluid must continue to flow across the bed to remove the product. At lower residance time, the rate of reaction or conversion of the reactant is low; and with too high a residance will form dark polymers or tars. So the flow rate or the residance time of the compounds in the packed bed of the catalyst has to be optimize to get better yield of the desired product and to minimize the polymerization of the product. In the present method the residance time of the compounds in the packed bed of the catalyst is in the range of 30 to 180 minutes, more preferably in between 75 to 150 minutes.
The present invention is directed to a process for continuous aldol condensation between acetaldehyde and MEK to produce methyl pentenone(3-methyl 3-Pente2none) using heterogeneous catalyst. Methyl pentenone is an intermediate in the reaction to produce Iso E Super, which is a widely used synthetic aroma chemical. Generally, aldol condensation reactions are acid as well as base catalyzed reactions. Conventional process for synthesis of methyl pentenone involves a batch homogeneous reaction between acetaldehyde and MEK, catalyzed by sulphuric acid. This follows series of steps such as neutralization of crude reaction mixture, water wash and then distillation. Also this process produces large residue (polymerized product) after distillation. So a large number of effluents are coming out of this process. Accordingly, it would be desirable to provide a process for continuous preparation of methyl pentenone using heterogeneous catalyst, which has acidic groups bound on it and it can be easily separated from crude mixture. This process eliminates the steps of neutralization and washing of crude reaction mixture water which generate large quantity of effluent. So the crude mixture after reaction can be directly distilled and/or flash distilled (online) and also it minimizes residue formation after distillation.

Method for continuous production of methyl pentenone (3-Methyl 3-Pente2none) comprising
steps of
(a) contacting acetaldehyde and methyl ethyl ketone (MEK) in ratio with a cation exchange resin at pressure 2.5 kg/cm2 to 10 kg/cm2 and at temperature 60°C to 100°C.
(b) distillating outlet from step (a) to get mixture of methyl pentenone and methyl ethyl ketone
(c) distillating mixture of methyl pentenone and methyl ethyl ketone to get pure methyl pentenone
In Method of present invention wherein before contacting acetaldehyde and methyl ethyl ketone (MEK) in ratio with a cation exchange resin, acetaldehyde and methyl ethyl ketone are mixed in mixing tank to create desirable pressure in reactor.
In present method, temperature profile of reactor kept in the range between 60°C to 100°C with variation or at same temperature. Yet another embodiment of invention, the packed bed reactor used is the double pipe cylindrical tube, in which operating temperature is maintained by circulating hot water or steam through the annular space between the two pipes. However, the temperatures for the reaction may also be obtained from the heating of the reaction mixture external to the reaction zone.
In the method, out let from reactor is fed to distillation column. Outlet of step (a) comprises mixture of acetaldehyde, methyl pentenone and methyl ethyl ketone to separate pure acetaldehyde, Acetaldehyde is recycled to feed stream of reactor.
Mixture of methyl pentenone and methyl ethyl ketone is further subjected to distillation to get pure methyl pentenone.
Thus process equipments comprises storage tank for acetaldehyde, storage tank for methyl ethyl ketone, online mixer, reactor for contacting acetaldehyde and methyl ethyl ketone in ratio with a cation exchange resin, acetaldehyde distillation column, acetaldehyde condensation column, methyl pentenone & methyl ethyl ketone distillation column and storage tank therein.

The cation exchange resin catalyst under the above described conditions acts efficiently to carry out aldol condensation reactions, more specifically for production of methyl pentenone with good yield and less byproduct formation.
Form the table-1 it was observed that for the flash distillation contains less high boiler as compare batch distillation. In the old process the high boiler content was 27%. Hence it can be conclude that flash distillation reduce the high boiler content. But over all MPO degradation or MPO non degradation was not determined. Also the MEK and MPO contain was not quantified and results are based on our analysis.
Table -1

Composition of MEK 45.6% in feed Feed contain
MPO 54.4%+ high boiler High boiler
Flash distillation 104.83 gm 13.83%
Batch distillation 142.01 gm 19.01%
The conditions for distillation were varied and the effect of residual distillation at 90°C and 10mm of Hg was determined.
The reaction was carried out at 70°C to check variation in high boiler on evaporation and MPO yield. For each expt. initially dead volume (250 ml) was collected as separate fraction and then different fraction were collected. These fractions were distilled at 100°C with full vacuum and then analyzed by GC.
Reaction conditions:
• Resin volume: 290 ml
• Feed: 28% acetaldehyde + 70% MEK
• Temperature: 70°C
• Pressure: 0.8 to 1.2 bar
• Flow rate: 2 ml/min
Overall results:

Initial
raw
material After catalysis After distillation High boiler MPO MEK initial MEK final Yield MPO %high boiler on MPO
Expt 1 356 368.6 339.7 4 75.2 224,3 156.13 80.1 5.32

Expt2 548 514.6 481 11 133.19 345.34 196.78 65.86 8.26
Expt3 560 528.4 475.1 9.7 131.85 352.9 203.67 64.91 7.36
Expt4 396 398 367.5 7.8 102.93 249.55 159.68 84.14 7.S8
| Expt5 344 331.4
301.4 5.7 81.55 216.78 131.67 70.38 6.99
Reaction was carried out in a jacketed column of 10 cm id * 150 cm length was packed with regenerated fresh resin. A storage tank was connected prior to this column for storage of reactants. Feed was passed with N2 pressure through column at constant pressure of 4 kg/cm2. Column temperature was maintained by circulating mixture of steam and hot water through jacket. Outlet flow rate was maintained with rotameter. Temperature was monitored at the bottom of the column and at the middle, outside the jacket.
Observations: During the course of reaction the bottom temperature was 70 ± 2°C, but the temperature at the jacket surface was 82 ± 2°C, which was quite high from our desired temperature. This temperature rise was due to exothermicity of the reaction. Color of the outlet MPO crude fraction was very dark brown also it was appeared like emulsion.
The present invention will be further illustrated by the following specific examples but not limited to these
Example 1
300 ml cation exchange resin catalyst is packed in the column having coil condenser is attached to the column having valve at the bottom. Temperature controller is attached to the column with the help of pump or by application of pressure and desired flow rate was maintained. The column is maintained at temperature of 100°C. Reaction mixture composed of 70% acetaldehyde and 30% methyl ethyl ketone (MEK) by weight is passed through column with residance time maintained at 150 minute. Analytical determinations after distillation showed that MEK conversion was 42.7% and methyl pentenone yield on MEK.

was 79.33% with productivity was 108.9 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 7.35% of the MPO.
Example 2
Steps of example 1 are carried out using same experimental set up as of Example 1, with temperature is maintained at 60°C. Reaction mixture composed of 33% acetaldehyde and 67% methyl ethyl ketone by weight was passed through column with residance time maintained at 50 minute. Analytical determinations after distillation showed that MEK conversion was 44.66% and MPO molar yield on MEK was 76.66% with productivity was 110.97 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 5.22% of the MPO.
Example 3
The reaction is carried out using same experimental set up as in Example 1, with temperature was maintained at 70°C. Reaction mixture composed of 40% acetaldehyde and 60% methyl ethyl ketone by weight are passed through column with residance time maintained at 75 minute. Analytical determinations after distillation showed that MEK conversion was 31% and MPO molar yield on MEK was 76.13% with productivity was 152.8 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 7.91% of the MPO.
Example 4
The reaction is carried out using same experimental set up as in Example 1, with temperature was maintained at 80°C. Reaction mixture composed of 50% acetaldehyde and 50% methyl ethyl ketone by weight is passed through column with residance time maintained at 100 minute. Analytical determinations after distillation showed that MEK conversion was 49.32% and MPO molar yield on MEK was 78.92% with productivity was 124.15 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 8.2%) of the MPO. Example 5
The reaction is carried out using same experimental set up as in Example 1, with temperature was maintained at 70°C. Reaction mixture composed of 25% acetaldehyde and 75% methyl

ethyl ketone by weight was passed through column with residence time maintained at 150 minute. Analytical determinations after distillation showed that MEK conversion was 28.55% and MPO molar yield on MEK was 79.24% with productivity was 82.48 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 3.23% of the MPO.
Example 6
The reaction is carried out using same experimental set up as in Example 1, with temperature is maintained at 90°C. Reaction mixture composed of 20% acetaldehyde and 80% methyl ethyl ketone by weight was passed through column with residence time maintained at 30 minute. Analytical determinations after distillation showed that MEK conversion was 25.1% and MPO molar yield on MEK was 85.8% with productivity was 85.84 mg MPO/ml resin.hr. Polymerized product (high boiler) formation was 2.75% of the MPO.
Example 7
The reaction is carried out using same experimental set up as in Example 1, with temperature is maintained at 65°C. Reaction mixture composed of 15% acetaldehyde and 85% methyl ethyl ketone by weight is passed through column with residence time maintained at 130 minute. Analytical determinations after distillation showed that MEK conversion is 23.24% and MPO molar yield on MEK was 82.52% with productivity is 77.83 mg MPO/ml resin.hr. Polymerized product (high boiler) formation is 5.99% of the MPO.
Example 8
Pilot scale reaction is carried out similar to the one which is used in earlier examples. A packed bed column has dimension of 150x10 cm. A storage tank was connected prior to this column for storage of reactants. Feed is passed with N2 pressure through column at constant pressure of 10 kg/cm2. Column temperature is maintained by circulating mixture of steam and hot water through jacket. Outlet flow rate is maintained by throttling the bottom valve and monitored with rotameter.
10.0 L cation exchange resin catalyst is packed in the column and it is maintained at temperature of 80°C. Reaction mixture composed of 30% acetaldehyde and 70% methyl ethyl ketone by weight is passed through column with flow rate maintained as 4 LPH i.e. residance time maintained is 100 minute.

Total of 100 kg feed was passed and reaction was carried out for 44 hours. Analytical determinations after distillation showed that 42.28 kg MEK is consumed in the reaction and which produces 43.27 kg MPO. The MEK conversion is 52.85% and MPO molar yield on MEK is 75.18% with productivity was 0.98 kg MPO/hr. Polymerized product (high boiler) formation was 18.6% of the MPO.
Example 9
Pilot scale reaction is carried out similar to the one which is used in earlier examples. A packed bed column has dimension of 150x10 cm. A storage tank was connected prior to this column for storage of reactants. Feed is passed with N2 pressure through column at constant pressure of 5 kg/cm2. Column temperature is maintained by circulating hot water through jacket. Outlet flow rate is maintained by throttling the bottom valve and monitored with rotameter.
10.0 L cation exchange resin catalyst is packed in the column and it is maintained at temperature of 70°C. Reaction mixture composed of 20% acetaldehyde and 80% methyl ethyl ketone by weight is passed through column with flow rate maintained as 4 LPH i.e. residance time maintained is 150 minute.
Total of 150 kg feed was passed and reaction was carried out for 44 hours. Analytical determinations after distillation showed that 46.8 kg MEK is consumed in the reaction and which produces 55.01 kg MPO. The MEK conversion is 58.5% and MPO molar yield on MEK is 86.5% with productivity was 1.25 kg MPO/hr. Polymerized product (high boiler) formation was 4.3% of the MPO.
Example 10
Pilot scale reaction is carried out similar to the one which is used in earlier examples. A packed bed column has dimension of 150x10 cm. A storage tank was connected prior to this column for storage of reactants. Feed is passed with N2 pressure through column at constant pressure of 4 kg/cm2. The feed is preheated using online preheater to 60-65C and the passed through column. Column temperature is maintained by circulating hot water through jacket. Outlet flow rate is maintained by throttling the bottom valve and monitored with rotameter. 10.0 L cation exchange resin catalyst is packed in the column and it is maintained at temperature of 72°C. Reaction mixture composed of 20% acetaldehyde and 80% methyl ethyl

ketone by weight is passed through column with flow rate maintained as 5 LPH i.e. residance time maintained is 120 minute.
Total of 100 kg feed was passed and reaction was carried out for 25 hours. Analytical determinations after distillation showed that 28 kg MEK is consumed in the reaction and which produces 33.76 kg MPO. The MEK conversion is 35% and MPO molar yield on MEK is 88.3% with productivity was 1.35 kg MPO/hr. Polymerized product (high boiler) formation was 3.2% of the MPO.

Claims We claim,
1. Method for continuous production of methyl pentenone (3-Methyl 3-Pente2none)
comprising steps of
(a) contacting acetaldehyde and methyl ethyl ketone (MEK) in ratio with a cation exchange resin at pressure 1.5 kg/cm2 to 10 kg/cm2 and at temperature 60°C to 100°C in a reactor to give in outlet of methyl pentenone, acetaldehyde, methyl ethyl ketone and water.
(b) distillating outlet from step (a) to get mixture of acetaldehyde and methyl ethyl ketone and water.
(c) distillating mixture of methyl pentenone and methyl ethyl ketone to get pure methyl pentenone

2. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 wherein cation exchange resin is selected from strong cationic exchange resin.
3. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 wherein acetaldehyde and methyl ethyl ketone are mixed in mixing tank or mixed in online mixture with applied pressure/ with pressure in the range of 1.7 Kg/cm2 to 4 kg/cm2 in reactor.
4. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 wherein contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is preferably carried out in temperature range of 60 degree C to 85 degree C.
5. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 wherein reactor is packed bed reactor selected from jacketed packed bed reactor and multi tube reactor.

6. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 5 wherein packed bed reactor is multi tube reactor.
7. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 5 wherein temperature of reactor is maintained uniform by circulating hot water or steam flow rate in at multiple points.
8. Method for continuous production of methyl pentenone (3-Methyl 3-Pente-2-none) as claimed in claim 1 wherein acetaldehyde and methyl ethyl ketone (MEK) are in ratio of 15 to 80 % of acetaldehyde and 20 to 85 % of methyl ethyl ketone (MEK) by weight.
9. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 and 5 wherein contacting acetaldehyde and methyl ethyl ketone (MEK) with a cation exchange resin is carried out in packed bed reactor in residence time of reactants in reactor, in the range between 30 to 180 minutes.
10. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2one) as
claimed in claim 1 wherein contacting acetaldehyde and methyl ethyl ketone (MEK) with
a cation exchange resin is carried with at least one reactant in liquid phase.
11. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1 wherein pressure in the reactor is preferably selected in the range 2.5 kg/cm2 to 10 kg/cm2 such that at that pressure all components will remain in liquid phase based on concentration of reactants.
12. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 9 wherein residence time of reactants in reactor is preferably in the range between 50 to 150 minutes.
13. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1, wherein outlet from step (a) is distilled out to get mixture of water and methyl ethyl ketone and Acetaldehyde is recycled to feed stream of reactor by removing water.

14. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in claim 1, mixture of methyl pentenone and methyl ethyl ketone is further distilled to get pure methyl pentenone.
15. Method for continuous production of methyl pentenone (3-Methyl 3-Penten-2-one) as claimed in above claims and in examples disclosed herein.