RECENTLY, Bradley has proposed a theory which correlates and predicts the structures of metallic alkoxides1. At the moment, Bradley's theory cannot be fully developed because of the lack of direct structural information. In particular, it is not known whether lithium methoxide is ionic, as generally assumed, or whether it is a giant polymer2. This communication describes the structure of lithium methoxide, which is shown to be similar to that of lithium hydroxide3. Although the structure has some features reminiscent of a giant two-dimensional polymer, it would normally be considered ionic.
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The present invention relates to chemical raw material synthesis field, and in particular to a kind of synthetic method of lithium methoxide.
Publication No. CNA Chinese patent literature discloses a kind of production technology of solid potassium alcoholate, with liquid alcohol Potassium is raw material, and liquid potassium alcoholate is concentrated by evaporation, dries step completion, and then blowing is packed, and obtains solid potassium alcoholate, vacuum is controlled therebetween Spend for 0.08~0.1Mpa, temperature is 75~170 DEG C.This method dries lithium alkoxide solution, drying effect using rake drying equipment It is limited, and the lithium alkoxide solid drying prepared is not thorough, lithium alkoxide solid product easily lumps, and the solvent remained in material is more, holds It is easily caused lithium alkoxide hydrolysis.
Publication No. CNA Chinese patent literature discloses a kind of production technology of lithium alkoxide, i.e., in reactor Middle addition lithium metal, is slowly added dropwise alcohol at 20~30 DEG C, is made during the course of the reaction by setting frozen water to cool outside reactor Reaction temperature is 60~80 DEG C, is dripped after alcohol, and insulation reaction completely, obtains liquid lithium alkoxide, is then sent to close drying and sets Standby middle concentrate drying is fixed lithium alkoxide.In this method, alcoholic solution is added dropwise in lithium metal, reaction is excessively fierce, produces A large amount of hydrogen that journey is produced easily cause danger&#;And in reaction early stage, stirring is difficult, and lithium metal is easily reunited, and reacts insufficient Or reaction time extension.
Publication No. CNA Chinese patent literature discloses one kind and prepares C 4 -C 8 The method of sodium alkoxide, including appoint The temperature of meaning ground under an inert atmosphere with about 110-140 DEG C, with the C less than stoichiometry 4 -C 8 Alkanol processing stirring in a solvent The metallic sodium dispersion mixed, includes the mixture of the first phase and the second phase to be formed, wherein first is mutually included in a solvent C 4 -C 8 Alkanol sodium solution, second mutually includes metallic sodium, isolates first and mutually obtains C as solution 4 -C 8 Sodium alkoxide product, also Arbitrarily by the continuous circular response of remaining mixture.
Lithium methoxide product mainly has two kinds of forms of solid and liquid, and solid methanol lithium can be made by liquid methanol lithium.Methanol The production method of lithium mainly has lithium metal method and alkaline process.Lithium metal method refers to that lithium metal directly reacts with methanol, obtained liquid Lithium methoxide product purity is higher.Alkaline process refers to lithium hydroxide dissolving generating lithium methoxide, the reaction with methanol reaction in methyl alcohol It is reversible reaction.Lithium methoxide alkalescence it is stronger than lithium hydroxide, lithium methoxide meet water easily occur back reaction regenerate lithium hydroxide and Methanol.
Lithium methoxide is a kind of important chemical products, with strong basicity and high activity, can be used as production vitamin A, dimension life The medicine intermediate of plain B, sulphadiazine etc..
The content of the invention
To solve existing invention lithium and methanol reaction fierceness, the easy caking of the solid methanol lithium of generation, residual solvent mistake High defect, the invention provides a kind of synthetic method of lithium methoxide.
A kind of synthetic method of lithium methoxide, comprises the following steps&#;
Step (1)&#;Under atmosphere of inert gases, lithium, stirring reaction are added into methanol&#;
Step (2)&#;After step (1) reaction terminates, concentration and recovery methanol, concentration raffinate, which is transferred in helical ribbon agitator, to be done It is dry, lithium methoxide is made&#;Pressure in helical ribbon agitator is that the temperature in 0.01-0.09MPa, helical ribbon agitator is 70-80 DEG C.
Alcohol is added to the synthetic method of lithium compared to existing, in the present invention, the stirring of whole course of reaction is good, The heat that reaction is produced can conduct quickly, safe.Reaction terminates rear recovery part GOOD TASTE methanol, contributes to reduction Production cost, reduces the processing load of follow-up drying process.
In addition, the drying effect for the helical-ribbon type drying equipment that the present invention is used is good, and at the temperature and vacuum, product Middle residual solvent is less than 1.5%, and the content of lithium methoxide is more than 99%.
Requirement of the reduction reaction process of lithium and methanol to moisture, air (such as oxygen, carbon dioxide) is higher, in production Before, enter line replacement, the preferred argon gas of described inert gas or nitrogen to the air in whole production system with inert gas.It is described Inert gas using preceding needing by drying process.
Hydrogen can be produced in course of reaction, during the course of the reaction, keeps inert gas to be in unimpeded state, contributes to purging H2, promote reaction process.
Equally, the methanol that step (1) is used need to be through except water process, preferably, the water content of methanol is less than 0.5wt%.
Preferably, in step (1), lithium adds the 1-10% that weight is methanol.
Under the material ratio, lithium methoxide is stable high in reaction solution, and course of reaction mixing effect is good, and temperature of reaction system can Control.
Preferably, in step (1), the lithium is added several times, the temperature for adding process control reaction system is less than 60 &#;&#;
In course of reaction, the desired amount of lithium metal is added in batches, can make lithium metal completely, highly effective reaction, reaction process is not Can be too fierce, it is prevented effectively from slug and methanol volatilization is wasted.
Preferably, the dosage of single batch of lithium is the 0.1-0.3wt% of methanol inventory.Lithium interval of adding is in batches 20-40min.The speed that adds of lithium also can be depending on the temperature according to reaction system, preferably, during adding lithium, control Temperature of reaction system is 40-50 DEG C.
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After the completion of the lithium metal of the inventory is added, stirring reaction to the complete solvent of solid, temperature rising reflux 0.5-1h steams Recovery methanol is evaporated, preferably, in step (2), the quantity of methyl alcohol of concentration and recovery is the 40-70% of step (1) methanol charged material weight.
The taste of the methanol of concentration and recovery is higher, and the water content of the methanol added compared to starting is lower, can be used as next Series-produced material.
Concentration raffinate contains more lithium methoxide, is directly transferred in helical ribbon agitator, and further precipitation is dried, and first is made The dry product of lithium alkoxide.The methanol of drying process recovery is also recyclable to be applied mechanically.
The helical ribbon agitator includes&#;
Kettle, including upper and lower two sections that split is set, and upper and lower two sections of chuck independence temperature control&#;
Ribbon impeller, in kettle, including hollow spindle and around the home hollow spindle periphery hollow spiral shell Band&#;Hollow spindle is connected with hollow ribbon bottom, and heat transferring medium interface is respectively provided with the top of hollow spindle and hollow ribbon.
The helical ribbon agitator also includes the drive mechanism of driving hollow spindle operating.
In step (2), in the drying process, hollow ribbon carries material upwards, and lithium methoxide wet feed is difficult to be deposited on bottom and tie Block, methanol evaporation efficiency is high&#;During discharging, ribbon impeller drive manner only need to be inverted, makes dried lithium methoxide The downward discharging of powder, it is easy to operate.
Heat transferring medium is filled with the chuck and the cavity of ribbon impeller that upper and lower two sections of kettle, can high efficiency regulatory The evaporation rate of methanol, while avoiding wet feed from being bonded in inner wall of kettle and ribbon impeller surface, helps that granularity is made With, purity is high, residual molten less lithium methoxide product.
In order to further reduce, lithium methoxide wet feed is hardened on inner wall of kettle, preferably, the outer rim of the hollow ribbon Press close to inner wall of kettle.
The top of the kettle is carried and is provided with filter in the middle part of separator, separator, and bottom is connected with kettle, top It is connected to vacuum line.
Separator is arranged on the top of kettle, and sets filter at vacuum port, can be prevented effectively from vacuum port blocking, So as to ensure the condition of high vacuum degree of helical ribbon agitator, the highly effective drying of concentration raffinate is ensured.
Temperature in helical ribbon agitator is to concentrating drying efficiency, the form of obtained lithium methoxide, the residual solvent of raffinate Deng influenceing larger, in the present invention, temperature in helical ribbon agitator can be in the cavity by kettle chuck and ribbon impeller Heat-conducting medium comes independence or coordinated signals.
Preferably, controlling heating rate to be 5-15 DEG C/30min in helical ribbon agitator from initial temperature.
Obtained lithium methoxide is in fine particle shape, no caking, the content of equipment residual solvent under described heating rate Less than 1.5wt%, can directly it pack.Compared with the drying mode such as existing rake, lithium methoxide powder produced by the present invention is uniform, nothing It need to carry out beating the operation bidirectionals such as powder, beneficial to the touch opportunity of reduction lithium methoxide and air and water, so as to ensure product quality.
In order to improve drying efficiency, preferably, the initial temperature in helical ribbon agitator is 40-50 DEG C.
Further preferably, 70 DEG C are risen to 10 DEG C/30min speed from initial temperature in helical ribbon agitator, then with 5 DEG C/30min speed is warming up to 80 DEG C.
The residual solvent levels for the lithium methoxide being dried to obtain under the preferred heating rate are less than 0.5wt%, lithium methoxide Purity is more than 99%.
The stir speed (S.S.) of helical ribbon agitator has influence to drying efficiency, residual solvent of lithium methoxide etc., preferably, spiral shell The speed of agitator of belt stirrer is 15-35rpm.Speed of agitator speed is too fast, and the energy consumption of lithium methoxide is big.Stir speed (S.S.) mistake Slowly, the evaporation rate of methanol is slower, and lithium methoxide is easily reunited, lumpd, and solvent is easily coated in particle, and the residual solvent of product contains Amount is high, and the stability of product is worse.
The time of drying process is 1-4h, and the drying process of existing rake drying equipment needs more than 20h, life of the invention Production efficiency is greatly improved.
Production security of the present invention is high, simple to operate, and production efficiency is high&#;Methanol high-quality can be recycled, obtained first Lithium alkoxide dry product it is prevented from caking, residual solvent is less.