CN105669374A - Synthetic method of lithium methoxide

The present invention relates to industrial chemicals synthesis field, be specifically related to the synthetic method of a kind of lithium methoxide.

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Publication number is the production technology that the Chinese patent literature of CNA discloses a kind of solid potassium alcoholate, with liquid potassium alcoholate for raw material, liquid potassium alcoholate evaporation and concentration, a dry step complete, then blowing packaging, obtain solid potassium alcoholate, controlling vacuum therebetween is 0.08'0.1Mpa, and temperature is 75'170 DEG C.The method adopts the dry lithium alkoxide solution of rake drying equipment, and drying effect is limited, and the lithium alkoxide solid drying of preparation is not thorough, and lithium alkoxide solid product easily lumps, and in material, the solvent of residual is more, it is easy to cause that lithium alkoxide is hydrolyzed.

Publication number is the production technology that the Chinese patent literature of CNA discloses a kind of lithium alkoxide, namely lithium metal is added in the reactor, it is slowly added dropwise alcohol at 20'30 DEG C, in course of reaction, by arranging frozen water cooling outside reactor, to make reaction temperature be 60'80 DEG C, after dripping alcohol, insulation reaction is complete, obtains liquid lithium alkoxide, is then sent in close drying equipment concentrate drying and is fixed lithium alkoxide. In the method, being dropped to by alcoholic solution in lithium metal, reaction is excessively fierce, and a large amount of hydrogen that production process produces easily cause danger; And in reaction early stage, stirring difficulty, lithium metal is easily reunited, and reacts insufficient or response time prolongation.

Publication number is that the Chinese patent literature of CNA discloses one and prepares C 4 -C 8 The method of sodium alkoxide, including at random under an inert atmosphere with the temperature of about 110-140 DEG C, with less than stoichiometric C 4 -C 8 Alkanol processes the metallic sodium dispersion that stirred in a solvent, and to form the mixture including first-phase and second-phase, wherein first-phase includes C in a solvent 4 -C 8 Sodium alkoxide solution, second-phase includes metallic sodium, isolates first-phase and obtains the C as solution 4 -C 8 Sodium alkoxide product, also arbitrarily by continuous for remaining mixture circular response.

Lithium methoxide product mainly has solid and two kinds of forms of liquid, and solid methanol lithium can be prepared by liquid methanol lithium. The production method of lithium methoxide mainly has lithium metal method and alkaline process. Lithium metal method refers to that lithium metal directly reacts with methanol, and the liquid methanol lithium product purity obtained is higher. Alkaline process refer to Lithium hydrate is dissolved in methanol and methanol react generation lithium methoxide, this reaction is reversible reaction. The alkalescence of lithium methoxide is stronger than Lithium hydrate, and lithium methoxide is met water and easily occurred back reaction to regenerate Lithium hydrate and methanol.

Lithium methoxide is a kind of important chemical products, has strong basicity and high activity, can as the medicine intermediate producing vitamin A, vitamin B, sulfadiazine etc.

Summary of the invention

For solving existing invention lithium and methanol reaction fierceness, the easy caking of the solid methanol lithium of generation, residual solvent crosses high defect, the invention provides the synthetic method of a kind of lithium methoxide.

The synthetic method of a kind of lithium methoxide, comprises the following steps:

Step (1): under atmosphere of inert gases, adds lithium, stirring reaction in methanol;

Step (2): after step (1) reaction terminates, concentration and recovery methanol, concentration raffinate is transferred to helical ribbon agitator inner drying, prepares lithium methoxide; Pressure in helical ribbon agitator is 0.01-0.09MPa, and the temperature in helical ribbon agitator is 70-80 DEG C.

Compared to existing, alcohol being added the synthetic method to lithium, in the present invention, the stirring of whole course of reaction is good, and the heat that reaction produces can quickly conduct, and safety is high. Reaction terminates rear recovery part GOOD TASTE methanol, contributes to reducing production cost, reduces the processing load of follow-up dry run.

Additionally, the drying effect of the helical-ribbon type drying equipment of present invention employing is good, at described temperature and vacuum, in product, residual solvent is less than 1.5%, and the content of lithium methoxide is more than 99%.

The reduction reaction process of lithium and methanol is higher to the requirement of moisture, air (such as oxygen, carbon dioxide), before manufacture, with noble gas, the air in whole production system is replaced, the preferred argon of described noble gas or nitrogen. Described noble gas needs before use through dried.

Course of reaction can produce hydrogen, in course of reaction, keep noble gas to be in unimpeded state, contribute to purging H2, advance reaction process.

Equally, the methanol that step (1) adopts need to through the process that dewaters, and as preferably, the water content of methanol is less than 0.5wt%.

As preferably, in step (1), lithium add the 1-10% that weight is methanol.

Under this material ratio, the stable height of lithium methoxide in reactant liquor, course of reaction mixing effect is good, and temperature of reaction system is controlled.

As preferably, in step (1), described lithium adds several times, adds the temperature of process control reaction system lower than 60 DEG C.

In course of reaction, add the desired amount of lithium metal in batches, can make lithium metal completely, highly effective reaction, reaction process will not be too fierce, is prevented effectively from slug and methanol volatilization waste.

As preferably, the dosage of single batch of lithium is the 0.1-0.3wt% of methanol inventory. Lithium interval of adding is 20-40min in batches. The speed that adds of lithium is determined also dependent on the temperature of reaction system, as preferably, adding in the process of lithium, controls temperature of reaction system and is 40-50 DEG C.

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After the lithium metal of described inventory has added, stirring reaction is to the complete solvent of solid, temperature rising reflux 0.5-1h, Distillation recovery methanol, as 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, lower compared to the water content of the initial methanol added, and can be used as next series-produced material.

Concentration raffinate contains more lithium methoxide, is directly transferred in helical ribbon agitator, and further precipitation dries, and prepares the dry product of lithium methoxide. The methanol of dry run recovery is also recyclable to be applied mechanically.

Described helical ribbon agitator includes:

Kettle, upper and lower two sections arranged including split, and the chuck independence temperature control of upper and lower two sections;

Ribbon impeller, is arranged in kettle, including hollow spindle and around the home in the hollow ribbon that hollow spindle is peripheral; Hollow spindle connects with bottom hollow ribbon, and the top of hollow spindle and hollow ribbon is respectively provided with heat transferring medium interface.

Described helical ribbon agitator also includes the driving mechanism driving hollow spindle operating.

In step (2), in dry run, hollow ribbon is to lifting up material, and lithium methoxide wet feed is not easily deposited on bottom and lumps, and methanol evaporation efficiency is high; In discharging process, only need to reverse ribbon impeller drive manner, makes the dried downward discharging of lithium methoxide powder, easy to operate.

It is filled with heat transferring medium in chuck that kettle is upper and lower two sections and the cavity of ribbon impeller, the evaporation rate of energy high efficiency regulatory methanol, avoid wet feed to be bonded in inner wall of kettle and ribbon impeller surface simultaneously, contribute to preparing granularity all with, purity molten less lithium methoxide product high, residual.

Hardening on inner wall of kettle to reduce lithium methoxide wet feed further, as preferably, the outer rim of described hollow ribbon presses close to inner wall of kettle.

The top of described kettle, with separator, is provided with defecator in the middle part of separator, bottom connects with kettle, and top is connected to vacuum line.

Separator is arranged on the top of kettle, and arranges defecator at vacuum port place, can be prevented effectively from vacuum port blocking, thus ensureing the condition of high vacuum degree of helical ribbon agitator, ensures the highly effective drying of concentration raffinate.

Temperature in helical ribbon agitator is bigger on impacts such as the concentration drying efficiency of raffinate, the form of prepared lithium methoxide, residual solvents, in the present invention, the temperature in helical ribbon agitator can come independence or coordinated signals by the heat-conducting medium in the cavity of kettle chuck and ribbon impeller.

As preferably, controlling heating rate in helical ribbon agitator from initial temperature is 5-15 DEG C/30min.

The lithium methoxide prepared under described heating rate is fine particle shape, and without caking, the content of equipment residual solvent, less than 1.5wt%, can directly be packed. Comparing with the drying mode such as existing rake, the lithium methoxide powder that the present invention prepares is uniform, it is not necessary to carries out beating the operation bidirectionals such as powder, is beneficial to the touch opportunity reducing lithium methoxide and air and water, thus products quality guarantee.

In order to improve drying efficiency, as preferably, the initial temperature in helical ribbon agitator is 40-50 DEG C.

It is preferred that, from initial temperature, rises to 70 DEG C with the speed of 10 DEG C/30min in helical ribbon agitator, then with the ramp of 5 DEG C/30min to 80 DEG C.

Under this preferred heating rate, the residual solvent levels of the dry lithium methoxide obtained is less than 0.5wt%, and lithium methoxide purity is more than 99%.

The drying efficiency of lithium methoxide, residual solvent etc. are had impact by the stir speed (S.S.) of helical ribbon agitator, and as preferably, the speed of agitator of helical ribbon agitator is 15-35rpm. Speed of agitator speed is too fast, and the energy consumption of lithium methoxide is big. Stir speed (S.S.) is excessively slow, and the evaporation rate of methanol is relatively slow, and lithium methoxide is easily reunited, lumpd, and is easily coated with solvent in granule, and the residual solvent levels of product is high, and the stability of product is worse.

The time of dry run is 1-4h, and the dry run of existing rake drying equipment needs more than 20h, and the production efficiency of the present invention is greatly improved.

Production security of the present invention is high, simple to operate, and production efficiency is high; Methanol can be recycled by high-quality, and the prevented from caking of the lithium methoxide dry product prepared, residual solvent is less.

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