CN110452091A - A kind of preparation method of l-menthol - Google Patents
A kind of preparation method of l-menthol Download PDFInfo
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- CN110452091A CN110452091A CN201910803961.9A CN201910803961A CN110452091A CN 110452091 A CN110452091 A CN 110452091A CN 201910803961 A CN201910803961 A CN 201910803961A CN 110452091 A CN110452091 A CN 110452091A
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- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
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- C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
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Abstract
The present invention provides a kind of preparation method of l-menthol, the preparation method, including esterification, fractionation, hydrolysis.This process optimization disconnecting route, by the way of fusion-crystallization, continuous production avoids complicated periodic crystallisation mode, reduces the use of a large amount of solvents, improves the fractionation efficiency 40% of technique, reduces energy consumption 20%, improves production efficiency 40%.The present invention splits process and does not need recrystallization and freezing and crystallizing, while improving the ee value of aromatic series l- menthyl ester up to 99% or more, and aromatic D-menthyl ester ee value is up to 98% or more.It is 50.25-50.75% that the present invention, which splits process aromatic D-menthyl ester one way molar yield, and the one way molar yield of aromatic series L- menthyl ester is 49.25-49.75%, and industrialized production is suitble to use.
Description
Technical field
The present invention relates to perfume synthesis technical fields, and in particular to a kind of preparation method of l-menthol.
Background technique
Menthol, scientific name are 5- methyl -2- isopropyl-cyclohexanol, and nickname menthol is colorless and transparent acicular crystal；L-
Menthol, also known as levorotatory menthol, fusing point: 44 DEG C, boiling point: 216.4 DEG C, specific rotatory power [α] d:=-48o；Index of refraction:
1.458；It is slightly soluble in water, is dissolved in the conventional organic solvents such as hexamethylene, ethyl alcohol and benzene.Penetrating odor with brisk sweet tea, has very
Strong refrigerant effect；And dextrorotation menthol has pungent penetrating odor, almost without refrigerant effect.Therefore have and answer extensively
Substantially levorotatory menthol, medical and health, food industry and it is daily in terms of can be used as local fiber crops
Liquor-saturated dose, cosmetics, fungicide, cigarette flavoring, refrigerant drink and food etc..
Since synthesis l-menthol has very high stability and higher economic interests, synthesis l-menthol takes in recent years
Biggish breakthrough was obtained, the document and report about synthesis l-menthol are very more.
At present by report and industrialized process route have it is following several:
(1) Patent No. CN101932543A and US9988331B2 kind are reported, BASF Aktiengesellschaft is using citral as original
Material, by the citronellal with chirality that catalyzes and synthesizes of expensive noble metal chiral catalyst, citronellal obtains hand by cyclisation
The isopulegol of property, the method that menthol is synthesized by crystallization and purification isopulegol and catalytic hydrogenation isopulegol.
(2) Japanese takasago company develops one using laurene as raw material, reacts to obtain N, N- diethyl with diethylamide lithium
Base geranyl amine, then by obtaining citronellal enamine under the catalyst of chiral catalyst (S)-BINAP-Rh, in acid condition
Lower acquisition dextrorotation citronellal, cyclisation obtains isopulegol under the catalysis of zinc bromide, and last catalytic hydrogenation obtains l-menthol.
BASF and takasago are expensive using catalyst when chiral catalyst progress asymmetric hydrogenation, and industrialization technology is difficult
Degree is big, and industrialization is easy inactivation with rear catalyst and is difficult to recycle, higher so as to cause production cost.
(3) l-menthol of the fragrant exploitation of German moral, the synthesis technology obtain hundred using metacresol as raw material, by alkylation
In fragrant phenol, obtain the DL menthol for being mixed with isomers after catalytic hydrogenation, DL menthol separated by rectifying, is then passed through
Transesterification synthesizes DL- Menthyl, and single D L Menthyl crystal seed is added, passes through repeated multiple times selection
Property crystallization prepare L- Menthyl, then hydrolysis obtains pure l-menthol.
Solution crystallization processes fractionation effect using the technique of Menthyl is not relatively high, and single splits efficiency not
Height needs repeated multiple times fractionation to crystallize, and causes fractionation crystallization process cumbersome, leads to production efficiency decline and the production cost increases.
Also there are much being described as follows for l-menthol preparation in other patents:
One kind is described in CN103468779A using Thymol as raw material, and hydrogen is added by the compound noble metal catalyst of palladium type
Reaction obtains peppermint alcohol mixture, and the DL- menthol after rectifying, which passes through, obtains DL- menthyl ester with the esterification of acylating reagent,
Menthyl ester is hydrolyzed to obtain l-menthol under the action of hydrolase is complete cellularised onion Bu Keshi bacterium.Use biological enzyme
When as catalyst being split or carried out the approach preparation l-menthol of asymmetric esterification and asymmetric hydrolysis with microorganism,
Biological enzyme preparation and discovery are difficult, are easy inactivation, and cost is higher.
The patent of Patent No. CN105461516A describes one kind directly using Thymol as raw material, by adding hydrogen, ester
Exchange obtains benzoic acid DL- menthyl ester, is split by preferential crystallization method para Toluic Acid's DL- menthyl ester, obtains benzoic acid L-
Menthyl ester and benzoic acid D- menthyl ester, D and L- menthyl ester obtain product l-menthol and D- menthol, D- after hydrolysis respectively
Menthol and DL- menthol fraction and DL- menthol isomer mixture are by repeating benefit after Raney's nickel isomerization after rectifying
Technique.It is the equal of the improvement technique to the fragrant technique of moral.The above method is the optimization to the fragrant technique of moral, entire excellent
There is still a need for a large amount of solvent during first crystallisation, solvent recovery can also consume a large amount of energy consumption, and solvent in crystallization process
In can remain a large amount of solute, although can recycle influences industrialized yield；This method is needed by splitting work simultaneously
The ee value of sequence, recrystallizing technology, freezing and crystallizing process, the benzoic acid l- menthyl ester after splitting process is only 80%.
In conclusion there are following for the split process of benzoic acid D, L- menthyl ester at present in the preparation method of l-menthol
Problem: solvent usage is big, and recycling energy consumption is high, and can remain a large amount of solute in crystallization process in solvent, although can recycle
But influence industrialized yield；The ee value for individually splitting the benzoic acid L- menthyl ester that process obtains is lower, needs to combine and tie again
Brilliant process could improve the ee value of benzoic acid L- menthyl ester.
Summary of the invention
In view of the above shortcomings of the prior art, the present invention provides a kind of preparation method of l-menthol, realizes following invention
Purpose:
(1) crystallization is split with the progress of fused junction crystallization, is participated in without solvent, more high-efficiency environment friendly, energy consumption are lower；
(2) recrystallization and freezing and crystallizing are not needed, while improving the ee value of aromatic series L- menthyl ester；
(3) yield for splitting process aromatic series L- menthyl ester is improved, improves the yield of l-menthol, suitable industrialized production makes
With.
Used technical solution is the present invention for achieving the above object:
A kind of preparation method of l-menthol, includes the following steps:
(1) aromatic D, the preparation of L- menthyl ester
It is added D in reaction kettle of the esterification, l-menthol, aromatic series methyl esters, highly acid sulfonate resin, 60-100 DEG C of reaction temperature,
Preferably 80-100 DEG C, Depressor response, reaction generates aromatic D, L- menthyl ester；After the reaction was completed, it filters, filtrate decompression distillation
Separate unreacted D, l-menthol and aromatic series methyl esters, recovery；The aromatic D of recycling, L- menthyl ester enter crystallization and tear open
Operation break-down.
The Depressor response, pressure 2000-10000pa, reaction time 5h；
Aromatic D, the molar yield of L- menthyl ester are 98.75-99.15%.
The structural formula of the aromatic series methyl esters is
R1, R2, R3, R4, R5 refer to that mutually independent is hydrogen or the alkyl of C1-C5, n 0,1,2,3；
Preferably methyl benzoate, methyl phenylacetate, methyl p-methyl benzoate；
The molal quantity of the aromatic series methyl esters is D, 1.2-5.5 times of l-menthol molal quantity, preferably 1.6-1.8 times；It is described
Highly acid sulfonate resin and D, the mass ratio of l-menthol is 5%-20%.
(2) aromatic D, the fractionation of L- menthyl ester
By aromatic D, L- menthyl ester is entered in at least melting crystallizer of second level, and it is molten then to carry out heat preservation at a certain temperature
Melt is brilliant, and D- menthyl ester crystal seed is added in level-one melting crystallizer, and L- menthyl ester crystal seed is added in second level melting crystallizer,
When starting crystallization, start continuous feeding and discharging, level-one melting mother liquor enters second level melting crystallizer, the mother of second level melting crystallizer
Liquid enters discharge tank, returns to raw material tank from discharge tank, enters level-one melting crystallizer as raw material, realizes continuous production, control
Input and output material speed processed, maintains the overflow situation of crystallizer.
Every 2 of melting crystallizer are one group, can choose suitable crystallizer group number according to yield, and level-one is molten in every group
Melt crystallizer and second level melting crystallizer respectively corresponds D- menthyl ester and L- menthyl ester；The mould temperature controls precision
0.1-0.5 DEG C, crystallization needs to put into corresponding crystal seed every time, and crystallization does not need to put into crystal seed again after starting, until weight next time
It is new to drive；Crystallization temperature is lower than 1-10 DEG C of fusing point, preferably 2-6 DEG C of simple L- menthyl ester；Specific temperature is according to different
Group is determined through overtesting.
Further preferably are as follows:
Aromatic D is added into firsts and seconds melting crystallizer, L- menthyl ester is then turned on each crystallizer down cycles
Pump, controlling temperature in firsts and seconds melting crystallizer by external heat exchanger is 45-55 DEG C, preferably 50-55 DEG C, is then delayed
Slow to cool down 2-4 DEG C, maintain to fluctuate above and below temperature after cooling down (can recycle realization temperature fluctuation no more than 0.2 DEG C by big flow
Become smaller), D crystal seed is added in level-one melting crystallizer respectively, L crystal seed is added into second level melting crystallizer, continues to keep the temperature
After 60min-90min, the discharging of firsts and seconds melting crystallizer is slowly opened, the discharging of level-one melting crystallizer is by the first filtering
Entering second level melting crystallizer after heat exchanger 3, second level melting crystallizer enters discharge tank by the second filtering discharging of heat exchanger 4,
Control discharging speed opens the charging of level-one melting crystallizer simultaneously, maintains material liquid level in crystallizer, controls certain disengaging
Expect speed.After level-one melting crystallizer and second level melting crystallizer continuous operation 10h-12h, switching level-one melting crystallizer goes out
Material to third filters heat exchanger 5, and switching second level melting crystallizer discharges to the 4th filtering heat exchanger 6, continues continuous fusion crystallization.
First filtering heat exchanger 3 rinses crystal with D- menthyl ester, and the second filtering heat exchanger 4 rinses crystal with L- menthyl ester, and flushing finishes
Afterwards, discharged it in respective storage tank after rising temperature for dissolving crystal, benzoic acid D- menthyl ester discharging ee value can achieve 98.0% with
On, benzoic acid L- menthyl ester discharging ee value can achieve 99.0% or more.
Cool down to the first filtering heat exchanger 3 and the second filtering heat exchanger 4, to level-one melting crystallizer and second level fusion-crystallization
Device is again after continuous operation 10h-12h, switch filtering device, constantly repeatedly draw operation, realizes Crystallization Continuity.
Remarks: crystal seed addition when feeding intake for the first time, later period do not need to add crystal seed again, crystallization operation proceed to it is certain
Again decrease temperature crystalline again after needing whole rising temperature for dissolving to remove brilliant dirt after time.
3, aromatic series L- peppermint ester hydrolysis
Aromatic series L- menthyl ester and methanol, highly acid sulfonate resin, compressive reaction, pressure 2-8bar, temperature are added in reaction kettle
60-100 DEG C, reaction generates l-menthol and aromatic series methyl esters, filters after the reaction was completed, and excessive methanol and life are recycled in filtrate rectifying
At aromatic series methyl esters recover esterif iotacation step, l-menthol is final products after rectification process.
4, aromatic D-peppermint ester hydrolysis
Aromatic D-menthyl ester and methanol, highly acid sulfonate resin, compressive reaction, pressure 2-8bar, temperature are added in reaction kettle
60-100 DEG C, reaction generates D menthol and aromatic series methyl esters, filters after the reaction was completed, and excessive methanol and life are recycled in filtrate rectifying
At aromatic series methyl esters recover esterif iotacation step, D- menthol passes through the ester isomerization of rectification process rear enclosure.
In the step 3 and step 4, the mass ratio of the highly acid sulfonate resin and menthyl ester is 5%-28%, first
The ratio of alcohol molal quantity and the molal quantity of menthyl ester is 2-5:1；Reaction temperature is 60-100 DEG C, preferably 80-100 DEG C, is reacted
Pressurization carries out, reaction pressure 2-8bar, preferably 5-8bar.
The invention adopts the above technical scheme, compared with prior art, has the advantages that
This process optimization disconnecting route, by the way of fusion-crystallization, continuous production avoids complicated periodic crystallisation mould
Formula reduces the use of a large amount of solvents, improves the fractionation efficiency 40% of technique, reduces energy consumption 20%, improves production efficiency
40%。
The present invention splits process and does not need recrystallization and freezing and crystallizing, while the ee value for improving aromatic series l- menthyl ester reaches
98-99% or more, aromatic D-menthyl ester ee value reach 97-98% or more.
It is 50.25-50.75%, aromatic series L- peppermint that the present invention, which splits process aromatic D-menthyl ester one way molar yield,
The one way molar yield of ester is 49.25-49.75%, and industrialized production is suitble to use.
Detailed description of the invention
Fig. 1 is the flow chart that process is split in l-menthol preparation process of the present invention
Wherein, 1- level-one melting crystallizer, 2- second level melting crystallizer, 3- first filter heat exchanger, and 4- second filters heat exchanger,
5- third filters heat exchanger, and 6- the 4th filters heat exchanger.
Specific embodiment
Hereinafter, preferred embodiments of the present invention will be described, it should be understood that preferred embodiment described herein is only used
In the description and interpretation present invention, it is not intended to limit the present invention.
A kind of preparation process of the l-menthol of embodiment 1
The following steps are included:
(1) benzoic acid D, L- menthyl ester are prepared
D, l-menthol 200.0g, methyl benzoate 300.0g, highly acid sulfonate resin are added into 1000ml three-necked flask
10g-40g controls vacuum degree in 2000pa-10000pa, controls reaction temperature at 80 DEG C, react to reaction system pulling vacuum
5h, the light component after reacting under vacuum is more advantageous to be separated in time, greatly speeds up the speed of reaction, filtrate entrance after filtering
Distillation system, resin recovery；Filtrate decompression rectifying obtains recycling methanol, the complete methyl benzoate of unreacted, benzene first respectively
Sour D, L- menthyl ester, this step molar yield situation see the table below:
(2) it splits
As shown in Fig. 1, it is 5L to level-one melting crystallizer 1 and each crystalliser volume of second level melting crystallizer 2(, just overflows
Stream) in be separately added into benzoic acid D, each 5L of L- menthyl ester, be then turned on each crystallizer down cycles pump, pass through external heat exchanger
Controlling temperature in level-one melting crystallizer 1 and second level melting crystallizer 2 is 55 DEG C, and then slow cooling maintains temperature to 51.6 DEG C
Fluctuation is no more than 0.2 DEG C (can recycle by big flow and realize that temperature fluctuation becomes smaller) about degree, respectively in level-one fusion-crystallization
D crystal seed is added in device 1, L crystal seed is added into second level melting crystallizer 2.
The D Seed charge is 0.1% of benzoic acid D, L- menthyl ester quality in level-one melting crystallizer 1；
The L Seed charge is 0.1% of benzoic acid D, L- menthyl ester quality in second level melting crystallizer 2；
The D crystal seed is benzoic acid D- menthyl ester；
The L crystal seed is benzoic acid L- menthyl ester；
After the subsequent continuation of insurance temperature 60min of crystal seed is added, slowly opens level-one melting crystallizer 1 and second level melting crystallizer 2 discharges, one
The discharging of grade melting crystallizer 1 enters second level melting crystallizer 2 after the first filtering heat exchanger 3, and second level melting crystallizer 2 passes through
The second filtering discharging of heat exchanger 4 enters discharge tank, returns to raw material tank from discharge tank, enters level-one melting crystallizer 1 as raw material,
Control discharging speed opens the charging of level-one melting crystallizer 1 simultaneously, and control discharging speed is 50ml/min, controls charging rate
Maintain material liquid level in crystallizer that overflow situation is presented.
After 2 continuous operation 10h-12h of level-one melting crystallizer 1 and second level melting crystallizer, switch level-one fusion-crystallization
The discharging of device 1 to third filters heat exchanger 5, and switching second level melting crystallizer 2 discharging to the 4th filtering heat exchanger 6 continues continuous molten
Melt is brilliant.First filtering heat exchanger 3 rinses crystal with benzoic acid D- menthyl ester, and the second filtering heat exchanger 4 uses benzoic acid L- peppermint
Ester rinses crystal, after flushing, is discharged it in respective storage tank after rising temperature for dissolving crystal, the discharging of benzoic acid D- menthyl ester
Ee value can achieve 98.0% or more, and benzoic acid L- menthyl ester discharging ee value can achieve 99.0% or more.
Cool down to the first filtering heat exchanger 3 and the second filtering heat exchanger 4, to level-one melting crystallizer 1 and second level fused junction
Brilliant device 2 is again after continuous operation 10h-12h, switch filtering device, constantly repeatedly draw operation, realizes Crystallization Continuity.
Remarks: crystal seed addition when feeding intake for the first time, later period do not need to add crystal seed again, and crystallization operation is after proceeding to 700h
Again decrease temperature crystalline again after needing whole rising temperature for dissolving to remove brilliant dirt.
Continuous to split process, the one way molar yield of benzoic acid D- menthyl ester is 50.25%, the list of benzoic acid L- menthyl ester
Journey molar yield is 49.75%.
(3) benzoic acid L- peppermint ester hydrolysis
Benzoic acid L- menthyl ester 260.0g and methanol 130.0g, highly acid sulfonate resin are added into 1000ml autoclave
26.0g, compressive reaction, reaction pressure 5.0bar, 80 DEG C of reaction temperature, reaction generates L menthol and methyl benzoate, has reacted
At rear filtering, filtrate rectifying recycles the methyl benzoate 135.1g of excessive methanol 96.0g and generation, recovers esterif iotacation step, L- is thin
Lotus alcohol 153.8g, is final products after rectification process, and product ee value can achieve 99.0% or more.Mole receipts of this step
Rate is 98.58%.
(4) benzoic acid D- peppermint ester hydrolysis
Benzoic acid D- menthyl ester 260.0g and methanol 130.0g, highly acid sulfonate resin are added into 1000ml autoclave
26.0g, compressive reaction, reaction pressure 5.0bar, 80 DEG C of reaction temperature, reaction generates D menthol and aromatic series methyl esters, has reacted
At rear filtering, filtrate rectifying recycles the aromatic series methyl esters 135.1g of excessive methanol 96.0g and generation, recovers esterif iotacation step, D- is thin
Lotus alcohol 153.2g, is final products after rectification process, and product ee value can achieve 98.5% or more.Mole receipts of this step
Rate is 98.18%.
D- menthol can be directly over isomerization reaction, and l-menthol is prepared, and can also pass through following step
(5), D, l-menthol is prepared.
(5) isomerization of D- menthol
50gNi-B-Ce/SiO2 amorphous alloy catalyst is added in fixed bed, is slowly introducing nitrogen, opens preheater and anti-
The heating for answering device is warming up to 150 DEG C, and nitrogen purges 0.5h, closes nitrogen valve, opens hydrogen valve, is slowly introducing hydrogen displacement nitrogen
Gas, hydrogen flow rate 20ml/min adjust counterbalance valve, maintain system pressure 3.0Mpa, and opening plunger pump is pumped into reaction system
Enter the mixture of D- menthol Yu other isomers, isomers derives from the isomers and D that this step generates, l-menthol preparation
Menthol other isomers that process generates, D- menthol when the steady production phase: D- peppermint in other isomers=65:35(raw material
Alcohol mass fraction 0-100% is ok), feed rate 1ml/min, temperature of reactor is stablized at 120 DEG C, and reactor is left
Reaction product cools down within the condenser, and obtains D, l-menthol and other isomers with Hydrogen Separation in gas-liquid separator
Mixture；Through D in vapor detection mixture, l-menthol accounts for 65.0-66.0%, other isomers account for 34-35%.
It is added to said mixture 600.0g in three-necked flask, carries out rectification under vacuum, rectification under vacuum obtains D, L- peppermint
Alcohol 388.1g, other isomers 208.1g；This step D, the molar yield of l-menthol are 99.5%.
D, l-menthol can be reused for above-mentioned preparing benzoic acid D, L- menthyl ester.
Above-mentioned steps (1) described D, l-menthol take prior art preparation, specific preparation method, including following step
It is rapid:
(1) D, L- isopulegol are prepared
Into 1000ml three-necked flask, loaded catalyst is added, and (load capacity that titanium forms in catalyst accounts for catalyst total amount
0.1-20%, co-catalyst load capacity account for the 0.01-5.0% of catalyst gross mass) 50g, solvent toluene 200g, it is added dropwise at 0 DEG C
100g citronellal, time for adding are controlled in 120min, and insulation reaction 10h is added dropwise, and catalyst is recovered by filtration, and filtrate is collected
298.3g, is transferred to subsequent processing, and recycling catalyst 50.2g is applied.The conversion ratio of this step of gas chromatographic detection be 99.2%, D,
L- isopulegol is selectively 98.35%.
(2) D, l-menthol are prepared
In 1000ml autoclave, the filtrate 298.3g and Raney's nickel catalyst 2.5g of a upper process is added, nitrogen is replaced three times,
Hydrogen is replaced three times, to reaction kettle punching press to 1.5Mpa, is warming up to 70 DEG C, is reacted 5h, react D, the selectivity of l-menthol is
98.20%, hydrogenation generates D, and l-menthol 97.96%, D, L- isomenthol 1.26%, other isomers are lower than 0.5%.
It extrudes reaction solution and carries out rectification under vacuum, obtain recycling toluene 195.6g, D, l-menthol 94.85g, menthol respectively
Other isomers 4.62g, the 98.19% of the molar yield of this cyclisation two step of hydrogenation.
A kind of preparation process of the l-menthol of embodiment 2
The following steps are included:
(1) phenylacetic acid D, L- menthyl ester are prepared
D, l-menthol 200.0g, methyl phenylacetate 330.0g, highly acid sulfonate resin 10- are added into 1000ml three-necked flask
40g controls vacuum degree in 2000pa-10000pa, controls reaction temperature at 100 DEG C, react 5h, very to reaction system pulling vacuum
Light component after the lower reaction of sky is more advantageous to be separated in time, greatly speeds up the speed of reaction, filtrate enters rectifying after filtering
System, resin recovery；Filtrate decompression rectifying, obtains methanol respectively, the complete methyl phenylacetate of unreacted, and phenylacetic acid D, L- is thin
Lotus ester, this walks practical molar yield and see the table below:
(2) it splits
As shown in Fig. 1, it is 5L to level-one melting crystallizer 1 and each crystalliser volume of second level melting crystallizer 2(, just overflows
Stream) in phenylacetic acid D, L- menthyl ester 10L is added, be then turned on each crystallizer down cycles pump, controlled by external heat exchanger
Temperature is 50 DEG C in level-one melting crystallizer 1 and second level melting crystallizer 2, and then slow cooling maintains in temperature to 47.3 DEG C
Lower fluctuation is no more than 0.2 DEG C (can recycle by big flow and realize that temperature fluctuation becomes smaller), respectively in level-one melting crystallizer 1
D crystal seed is added, L crystal seed is added into second level melting crystallizer 2.
The D Seed charge is 0.15% of phenylacetic acid D, L- menthyl ester quality in level-one melting crystallizer 1；
The L Seed charge is 0.15% of phenylacetic acid D, L- menthyl ester quality in second level melting crystallizer 2；
The D crystal seed is phenylacetic acid D- menthyl ester；
The L crystal seed is phenylacetic acid L- menthyl ester；
After the subsequent continuation of insurance temperature 70min of crystal seed is added, slowly opens level-one melting crystallizer 1 and second level melting crystallizer 2 discharges, one
The discharging of grade melting crystallizer 1 enters second level melting crystallizer 2 after the first filtering heat exchanger 3, and second level melting crystallizer 2 passes through
The second filtering discharging of heat exchanger 4 enters discharge tank, returns to raw material tank from discharge tank, enters level-one melting crystallizer 1 as raw material,
Control discharging speed opens the charging of level-one melting crystallizer 1 simultaneously, and control discharging speed is 50ml/min, controls charging rate
Maintain material liquid level in crystallizer that overflow situation is presented.
After 2 continuous operation 8h-10h of level-one melting crystallizer 1 and second level melting crystallizer, switch level-one melting crystallizer
1 discharging to third filters heat exchanger 5, and the discharging of switching second level melting crystallizer 2 continues continuous fusion to the 4th filtering heat exchanger 6
Crystallization.First filtering heat exchanger 3 rinses crystal, the second filtering phenylacetic acid L- menthyl ester of heat exchanger 4 with phenylacetic acid D- menthyl ester
Crystal is rinsed, after flushing, is discharged it to after rising temperature for dissolving crystal in respective storage tank, phenylacetic acid D- menthyl ester discharging ee
Value can achieve 97.0% or more, and phenylacetic acid L- menthyl ester discharging ee value can achieve 98.0% or more.
Cool down to the first filtering heat exchanger 3 and the second filtering heat exchanger 4, to level-one melting crystallizer 1 and second level fused junction
Brilliant device 2 is again after continuous operation 8h-10h, switch filtering device, constantly repeatedly draw operation, realizes Crystallization Continuity.
Remarks: crystal seed addition when feeding intake for the first time, later period do not need to add crystal seed again, and crystallization operation is after proceeding to 700h
Again decrease temperature crystalline again after needing whole rising temperature for dissolving to remove brilliant dirt.
Continuous to split process, the one way molar yield of phenylacetic acid D- menthyl ester is 50.75%, the list of phenylacetic acid L- menthyl ester
Journey molar yield is 49.25%.
(3) phenylacetic acid L- peppermint ester hydrolysis
Phenylacetic acid L- menthyl ester 274.0g and methanol 130.0g, highly acid sulfonate resin are added into 1000ml autoclave
25.0g, compressive reaction, reaction pressure 8.0bar, 100 DEG C of reaction temperature, reaction generates L menthol and methyl phenylacetate, reaction
It filters after the completion, the methyl phenylacetate 145.8g of excessive methanol 95.1g and generation are recycled in filtrate rectifying, recover esterif iotacation step, L-
Menthol 152.2g, is final products after rectification process, and product ee value can achieve 99.0% or more.Mole of this step
Yield is 97.58%.
(4) phenylacetic acid D- peppermint ester hydrolysis
Phenylacetic acid D- menthyl ester 274.0g and methanol 130.0g, highly acid sulfonate resin are added into 1000ml autoclave
20.0g, compressive reaction, reaction pressure 8.0bar, 100 DEG C of reaction temperature, reaction generates D menthol and methyl phenylacetate, reaction
It filters after the completion, the methyl phenylacetate 143.9g of excessive methanol 94.8g and generation are recycled in filtrate rectifying, recover esterif iotacation step, D-
Menthol 153.2g, is final products after rectification process, and product ee value can achieve 98.5% or more.Mole of this step
Yield is 98.18%.
D- menthol can be directly over isomerization reaction, and l-menthol is prepared, and can also pass through following step
(5), D, l-menthol is prepared.
(5) isomerization of D- menthol
50gNi-B-Ce/SiO2 amorphous alloy catalyst is added in fixed bed, is slowly introducing nitrogen, opens preheater and anti-
The heating for answering device is warming up to 150 DEG C, and nitrogen purges 0.5h, closes nitrogen valve, opens hydrogen valve, is slowly introducing hydrogen displacement nitrogen
Gas, hydrogen flow rate 15ml/min adjust counterbalance valve, maintain system pressure 2.0Mpa, and opening plunger pump is pumped into reaction system
Enter the mixture of D- menthol Yu other isomers, isomers is generated from the isomers and (2) step of the generation of this step
Isomers, D- menthol when the steady production phase: D- menthol mass fraction 0-100% may be used in other isomers=65:35(raw material
With), feed rate 1.3ml/min, temperature of reactor is stablized at 180 DEG C, leaves the reaction product of reactor within the condenser
It is cooling, and D, the mixture of l-menthol and other isomers are obtained with Hydrogen Separation in gas-liquid separator；Through vapor detection
D in mixture, l-menthol account for 60.0-63.0%, other isomers account for 37-40%.
It is added to said mixture 600.0g in three-necked flask, carries out rectification under vacuum, rectification under vacuum obtains D, L- peppermint
Alcohol 344.8g, other isomers 245.1g；This step D, the molar yield of l-menthol are 98.3%.
D, l-menthol can be reused for above-mentioned preparing benzoic acid D, L- menthyl ester.
Above-mentioned steps (1) the middle D, l-menthol are obtained using prior art preparation, specific preparation method, including
Following steps:
(1) D, L- isopulegol are prepared
Into 1000ml three-necked flask, loaded catalyst is added, and (load capacity that titanium forms in catalyst accounts for catalyst total amount
0.1-20%, co-catalyst load capacity account for the 0.01-5.0% of catalyst gross mass) 50g, solvent petroleum ether 200g, it is added dropwise at 0 DEG C
100g citronellal, time for adding are controlled in 120min, and insulation reaction 10h is added dropwise, and catalyst is recovered by filtration, and filtrate is collected
295.3g, is transferred to subsequent processing, and recycling catalyst 50.0g is applied.The conversion ratio of this step of gas chromatographic detection be 99.0%, D,
L- isopulegol is selectively 98.75%.
(2) D, l-menthol are prepared
In 1000ml autoclave, the filtrate 295.3g and Raney's nickel catalyst 3.0g of a upper process is added, nitrogen is replaced three times,
Hydrogen is replaced three times, to reaction kettle punching press to 1.5Mpa, is warming up to 70 DEG C, is reacted 4.5h, reacts D, the selectivity of l-menthol
It is 97.80%, vapor detection, which hydrogenates, generates D, l-menthol 96.27%, D, L- isomenthol 1.26%, other isomers are lower than
0.5%。
It extrudes reaction solution and carries out rectification under vacuum, obtain recycling toluene 193.6g, D, l-menthol 94.35g, menthol respectively
Other isomers 4.93g, the 98.00% of the molar yield of this cyclisation two step of hydrogenation.
Finally, it should be noted that the foregoing is only a preferred embodiment of the present invention, it is not intended to restrict the invention,
Although the present invention is described in detail referring to the foregoing embodiments, for those skilled in the art, still may be used
To modify the technical solutions described in the foregoing embodiments or equivalent replacement of some of the technical features.
All within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in of the invention
Within protection scope.
Claims (10)
1. a kind of preparation method of l-menthol, it is characterised in that: the preparation method, including esterification, fractionation, hydrolysis.
2. a kind of preparation method of l-menthol according to claim 1, it is characterised in that: the fractionation, fusion-crystallization
Device every 2 are one group, and every group includes level-one melting crystallizer and second level melting crystallizer, aromatic D are added, L- menthyl ester makes
It obtains melting crystallizer and is in overflow situation, melting temperature is cooled to, then slow cooling to crystallization temperature, in level-one fusion-crystallization
Aromatic D-menthyl ester crystal seed is added in device, aromatic series L- menthyl ester crystal seed is added into second level melting crystallizer, keeps the temperature, then
Continuous fusion crystallization is carried out, fractionation obtains aromatic D-menthyl ester, aromatic series L- menthyl ester.
3. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the mould temperature control
Precision processed is 0.1-0.5 DEG C；The crystallization temperature is lower than 1-10 DEG C of melting temperature.
4. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the crystallization temperature is lower than molten
Melt 2-6 DEG C of temperature；The aromatic D-menthyl ester crystal seed additional amount is aromatic D in level-one melting crystallizer, L- menthyl ester
The 0.05-0.15% of quality；The additional amount of the aromatic series L- menthyl ester crystal seed is aromatic D in second level melting crystallizer, and L- is thin
The 0.05-0.15% of lotus ester quality.
5. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the continuous fusion crystallization,
The discharging of level-one melting crystallizer enters second level melting crystallizer after filtering heat exchanger, and second level melting crystallizer is changed by filtering
Hot device discharging enters discharge tank, returns to raw material tank from discharge tank, enters level-one melting crystallizer as raw material, controls charging rate
Maintain material liquid level in crystallizer that overflow situation is presented with discharging speed.
6. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the heat preservation, time 60-
90min；The aromatic D, L- menthyl ester, be benzoic acid D, L- menthyl ester, phenylacetic acid D, L- menthyl ester, p-methylbenzoic acid D,
L- menthyl ester.
7. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the melting temperature is 45-
55℃；The crystallization temperature is lower than 2-4 DEG C of melting temperature；Temperature fluctuates up and down is no more than 0.2 DEG C.
8. a kind of preparation method of l-menthol according to claim 2, it is characterised in that: the continuous fusion crystallization,
The discharging of level-one melting crystallizer enters second level melting crystallizer after the first filtering heat exchanger, and second level melting crystallizer is by the
Two filtering heat exchanger dischargings；After continuous operation 10h-12h, switching level-one melting crystallizer, which discharges, filters heat exchanger to third,
Switching second level melting crystallizer discharges to the 4th filtering heat exchanger, continues continuous fusion crystallization；First filtering heat exchanger fragrance
Race's D- menthyl ester rinses crystal, and the second filtering heat exchanger rinses crystal, after flushing, rising temperature for dissolving with aromatic series L- menthyl ester
It is discharged it after crystal；It is molten to level-one melting crystallizer and second level to the first filtering heat exchanger and the second filtering heat exchanger cooling
After melting crystallizer and continuous operation 10h-12h, it is switched to the first filtering heat exchanger and the second filtering heat exchanger, constantly repeats to discharge
Crystallization Continuity is realized in operation.
9. a kind of preparation method of l-menthol according to claim 1, it is characterised in that: D, L- is added in the esterification
Menthol, aromatic series methyl esters, highly acid sulfonate resin, 60-100 DEG C of reaction temperature, Depressor response, reaction generates aromatic D, L-
Menthyl ester；The Depressor response, pressure 2000-10000pa, reaction time 5h；The molal quantity of the aromatic series methyl esters is
D, 1.2-5.5 times of l-menthol molal quantity；The highly acid sulfonate resin and D, the mass ratio of l-menthol are 5%-20%.
10. a kind of preparation method of l-menthol according to claim 1, it is characterised in that: the hydrolysis, highly acid tree
Rouge and the mass ratio of aromatic D-menthyl ester or aromatic series L- menthyl ester are 3%-28%, methanol and aromatic D-menthyl ester or fragrance
The molar ratio of race's L- menthyl ester is 2-5:1；Reaction temperature is 60-100 DEG C；Reaction pressurization carries out, reaction pressure 2-8bar.
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| CN110845305B (en) * | 2019-11-25 | 2022-06-28 | 安徽一帆香料有限公司 | Method for preparing L-menthol by adopting modified homogeneous catalyst |
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