CN1164595C - Prepn of alpha-chloro-hydrocarbon siloxane - Google Patents
Prepn of alpha-chloro-hydrocarbon siloxane Download PDFInfo
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- CN1164595C CN1164595C CNB011311312A CN01131131A CN1164595C CN 1164595 C CN1164595 C CN 1164595C CN B011311312 A CNB011311312 A CN B011311312A CN 01131131 A CN01131131 A CN 01131131A CN 1164595 C CN1164595 C CN 1164595C
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Abstract
The present invention relates to a method for preparing alpha-chlorohydrocarbon siloxane by an alcoholysis reaction of alpha-chlorohydrocarbon silane. The alpha-chlorohydrocarbon siloxane is prepared by the no-solvent liquid phase alcoholysis reaction of the alpha-chlorohydrocarbon silane. A nitrogen-containing compound is used as proton absorbing agents, reactants comprise 1 mol of chlorohydrocarbon silane, 3.0 to 3.6 mol of alcohol and 3 to 4.5 mol of the proton absorbing agents, the reaction temperature is 10 to 60 DEG C., the reaction time is 1 to 2 hours, the balancing time is 2 hours, and the alpha-chlorohydrocarbon siloxane product is obtained. Under the condition of the no solvent exists, urea is used as HCl absorbing agents to protect active chlorine atoms in an alpha-position, the content of hydrochloric acid in a goal product is less than 4 ppm, and the yield of the goal product (siloxane) is more than 98%. Formed urea salts are processed by a chemical method, the content of the hydrochloric acid is less then 50 ppm, and the urea salts can be reused or be used for fertilizer.
Description
Relates to the field of
The invention relates to a method for preparing α -chlorohydrocarbyl siloxane by alcoholysis reaction of α -chlorohydrocarbyl chlorosilane.
Background
α -chloro-alkyl chlorosilane is mainly used for preparing α -functional group silane coupling agent, and has the following characteristics and application:
(1) because the α -functional group silane coupling agent has more active property, the functional group silane coupling agent can be used as an ideal cross-linking agent of RTV silicone rubber, and has the advantages of high cross-linking speed, good adhesive force to other materials, rubber strength improvement and the like.
(2) Because the α -functional group silane coupling agent is not easy to break carbon-carbon bonds at high temperature, certain α -functional group silane coupling agents are applied to glass fiber reinforced plastics, mineral filled plastics and the like, and have better mechanical strength, heat resistance and water resistance than α -functional group silane coupling agents.
α -chlorohydrocarbylchlorosilanes, in particular chloromethyltrichlorosilane (ClCH)2SiCl3) The alcoholysis reaction method of (2) is not reported in detail in the literature, and the reaction mechanism of the alcoholysis reaction method and CH3SiCl3、(CH3)2SiCl2、CH2＝CHSiCl3The alcoholysis reaction of the organochlorosilane is basically similar. Predecessors about CH3SiCl3、(CH3)2SiCl2The alcoholysis reaction of (a) was studied in many ways and is summarized as follows:
Ger.offen.DE 950910 and Ger.offen.DE 950636 disclose that the alcoholysis rate depends primarily on the rate of nucleophilic attack, and that the higher the number of electronegative atoms or groups attached to the Si atom, the higher the alcoholysis rate, and that the alcoholysis of halosilanes is promoted with alkaline catalysts (e.g., sodium alkoxides). The stability of the alcoholysis product is, on the one hand, related to the size and number of the bonded organic groups of silicon atoms and increases with increasing volume and number; on the other hand, it is also related to the size of R in the OR group in the siloxane, and the smaller the R, the more unstable.
Us patent 2.381.138 describes that alcoholysis reactions can be carried out in low boiling solvents,such as petroleum ether, diethyl ether, benzene, toluene, the reaction producing HCl with very low solubility in the solvent, using an inert gas, such as N2The HCl can be blown out, and the product yield is improved.
Fr.patent 1.205.609, Brit patent 635726 describe alcoholysis reactions in which when an organochlorosilane is alcoholyzed using a lower alcohol, such as methanol, ethanol, and if the HCl formed is not removed in time, the latter will react with the alcohol to form RCl and H2The presence of water, however, tends to cause the organochlorosilane to undergo an alcoholysis reaction accompanied by a hydrolysis reaction. The reaction produces HCl which will produce the following side reactions:
de 842058 describes the addition of proton absorbers, such as tertiary amines, pyridine, quinoline, etc., in alcoholysis reactions. Structurally, these proton absorbers leave an unshared pair of electrons on the N atom which can combine with a proton to form a salt. When alcoholysis is carried out with sodium alkoxides instead of alcohols, high yields (85-90%) of alkoxysilanes are obtained, for example:
U.S. Pat. No. 4, 4.421.926 describes organochlorosilanes, e.g. 17% CH3SiCl3And 83% of (CH)3)2SiCl2Gas phase alcoholysis of the mixture in a ceramic rectangular saddle packed column with CH3OH is fed at four different column sections, CH3SiCl3And (CH)3)2SiCl2The mixture is fed overhead. The temperature of the overhead condenser is controlled to be-10-20 ℃, and the unreacted CH3Cooling OH, and then returning the OH to the tower, and cooling the generated HCl for absorption and utilization. The HCl content of the obtained product was 3.0%, (CH)3)2Si(OCH3)2The content is 65%, (CH)3)Si(OCH3)3The content is 13 percent, the high-boiling residue is 6.8 percent, and the total yield is 91 percent.
U.S. Pat. No. 4, 4.298.753 describes a continuous liquid phase alcoholysis process with vinyltrichlorosilane as the starting materialAnd ethanol enters a first reactor (provided with a ring-shaped glass tube, the length of the ring-shaped glass tube is 1250mm, the inner diameter of the ring-shaped glass tube is 100mm), the reaction temperature is controlled to be 15 ℃, after the reaction, the mixture enters a second reactor (a packed tower, ceramic intalox saddle packing with the thickness of 12mm multiplied by 12mm is filled in the packed tower, the height of the tower is 12000mm, the inner diameter of the tower is 200mm, and the height of the packing is 10000mm) from the other end of the ring-shaped glass tube, two-step gas phase alcoholysis is carried out2＝CHSi(OC2H5)3The purity is 99.7 percent, and the HCl content is less than 5 ppm.
U.S. Pat. No. 3, 4.039.567 discloses that in the alcoholysis of organochlorosilanes, the separation of HCl from the reaction products is difficult, and that inert gases such as nitrogen are generally introduced into the reaction system, and that falling-film evaporators are also used, which have a disadvantage; a large amount of HCl off-gas is produced and complete separation of HCl from the product cannot be achieved. In this patent, a separation tower is used, which has an inner diameter of 100mm and a height of 3800mm and is filled with a ceramic rectangular saddle packing of 6mm × 6 mm. The temperature of the condenser is controlled to be-48 ℃, trichlorosilane and methanol are fed in a liquid state, the HCl content in the product is less than 20mg/l, and pure HCl obtained from the other end of the condenser can be reused. The liquid trichlorosilane and the methanol are fed into a packed tower, the reaction temperature is kept enough, and the generated HCl is continuously distilled out of the tower.
In the gas phase esterification reaction of U.S. Pat. No. 4, 4.228.092, HCl is extracted in sections, and the obtained HCl does not contain impurities and pollute the environment, and can be directly used for preparing trichlorosilane. Acid absorbents are also not required. The esterification reaction may be carried out in a solvent such as hexane, heptane, isooctane, toluene, benzene, etc., to lower the boiling point of the raw materials. And (3) dropwise adding ethanol into the reactor, reacting at the boiling temperature (66 ℃) of methyltrichlorosilane, starting to vaporize the generated HCl, and keeping refluxing for 2-3 hours. Continuously dripping ethanol, keeping refluxing for 2-3 h, dripping all ethanol, boiling and refluxing. The obtained product can obtain 97 percent of CH after separation3Si(OC2H5)31.8% of CH3Si(OC2H5)2Cl, 1% high boiler.
Us patent 4.226.793, HCl formed during the alcoholysis reaction is partly dissolved in the reaction product and can be separated off after the reaction has ended. The reaction product was heated to boiling temperature and HCl was distilled off from the top of the reactor. Because the esterification reaction was carried out continuously, 96% HCl was recovered in the product, with HCl content<6 ppm.
Brit.patent 2.026.509，CH3SiCl3Reaction with methanol in N2Et is dropwise added into the system under protection3Mixture of N and PhMe to absorb HCl formed during the reaction, Et obtained3N.HCl and the solvent can be recycled.
Ger.offen.DE 3.617.719, Ger.offen.DE 3.617.729, CH 3 SiCl 3 and EtOH in Et3In the presence of N, 11.2% of CH can be obtained3SiCl382% of CH3Si(OC2H5)Cl2And CH3Si(OC2H5)2Cl。
In the above-mentioned patent, the HCl removal process is mostly carried out by heating to evaporate off HCl gas, compressing the HCl gas, and recovering the HCl gas. This method has the following disadvantages:
the HCl gas compression recovery process has no better solution.
The HCl gas is in contact with water to form a hydrochloric acid solution, so that the equipment is seriously corroded, and a large amount of HCl tail gas is formed.
HCl gas is evaporated out, a large amount of reactants are carried, the load of a condenser is increased, and the utilization of HCl is directly influenced by siloxane carried in the recovered HCl gas or hydrochloric acid solution.
In summary, the alcoholysis reaction of α -chlorohydrocarbyl chlorosilane to produce α -chlorohydrocarbyl siloxane is outlined below:
the method comprises the following steps: batch processes and continuous processes.
The method comprises the following steps of: solvent processes and solventless processes.
According to the state of reactants, the method is divided into: gas phase processes and liquid phase processes.
According to the reactor structure, the method comprises the following steps: kettle type reaction and tower type reaction.
The absorption of HCl can be done as follows:
proton absorbers, such as tertiary amines, pyridine, quinoline, and the like, are added.
Ceramic dielectrics such as CH are added3ONa、C2H5ONa, and the like.
α alcoholysis of chlorohydrocarbyl chlorosilanes the preparation of α -chlorohydrocarbyl siloxanes was carried out by the following general method:
if the HCl generated cannot be removed in time, ClRSi (OR')3Also, since the α -position chlorine atom is extremely reactive, unstable in the presence of alkalinity, and can undergo condensation reactions with hydrogen atoms, the siloxane structure will change, and therefore, it is important to select a suitable proton absorber.
Organic amine proton absorbent, such as aniline, diethylamine, etc. can have the following side reactions:
pure standing waves by antidune proton absorbent, such as sodium methoxide, sodium ethoxide, etc. can have the following side reactions:
the urea as a proton absorbent can perform the following complex reaction:
Due to the formation of urea salt complexes with ClCH2Si(OR)3No chemical reaction and effective protection of active chlorine atom. Furthermore, (NH)2)2After appropriate chemical treatment of CO&HCl, (NH)2)2The CO is separated out again and can be reused or used for soil fertilizers.
Disclosure of Invention
The invention aims to provide a method for preparing α -chlorohydrocarbyl alkoxy silane by adopting α -chlorohydrocarbyl chlorosilane solvent-free liquid phase alcoholysis reaction, wherein urea is used as an HCl absorbent under the condition of no solvent, active chlorine atoms at α -position are protected, the acid content in a product can be obviously reduced, the yield of a target product is improved, and the formed urea salt can be reused or used for fertilizers after being treated by a chemical method.
The invention is realized by the following steps: with chloromethyl trichlorosilane (ClCH)2SiCl3) The raw materials are subjected to liquid phase alcoholysis reaction with methanol or ethanol, and urea is used as an HCl absorbent. The reaction composition is ClCH2SiCl3Alcohol and urea in a ratio of 1: 3.0-3.6: 3-4.5(mol), controlling the reaction temperature at 10-60 ℃, the reaction time at 1.5 hours and the balance time at 2 hours. The specific operation is as follows:
the method adopts a process of dripping α -chloro-alkyl chlorosilane, controls the dripping speed of raw materials, and removes the generated heat of reaction in time, wherein the reactor is a glass reactor with condensation, and is heated in a water bath, and when the reaction temperature exceeds 60 ℃, cold water is introduced into the water bath or ice blocks are added to cool the water bath to below 60 ℃.
In the invention, the raw materials are chloromethyl trichlorosilane, alcohol and urea in a molar ratio of 1: 3.0-3.6: 3-4.5(mol), alcohol and HCl absorbent are added into a reaction kettle according to the ratio, the temperature is raised to 60 ℃, and α -chloroalkyl chlorosilane (ClCH) is dripped into the reactor2SiCl3). The HCl gas is vaporized and condensed to produce reflux. And controlling the dropping rate to keep the reaction temperature at 10-60 ℃. If the temperature is too high, industrial water can be introduced into the water bath for cooling, and the reaction time is 1.5 hours. After the completion of the dropwise addition, the reaction was terminated by refluxing in equilibrium for 2 hours. And settling and layering the obtained reaction product, discharging the lower urea salt, and obtaining the target product alkoxy silane by the reaction from the residual upper filter liquor.
In the invention, the raw material ethanol has the purity of more than or equal to 99.5 percent and the water content of ∠ 0.5.5, and the adopted absorbent urea has the requirements of more than or equal to 46.3 percent of total nitrogen content and ∠ 0.5.5 percent of water content.
According to the method for preparing α -chloro alkyl alkoxy silane by solvent-free liquid phase alcoholysis reaction of α-chloro alkyl chlorosilane, urea is used as an HCl absorbent under the condition of no solvent, α -site active wave chlorine atoms are protected, the hydrochloric acid content in a target product is less than 4ppm, the yield of the target product (siloxane) is more than 98%, and after the formed urea salt is treated by a chemical method, the hydrochloric acid content is less than 50ppm, so that the urea salt can be reused or used for fertilizers.
The method adopts α -chlorohydrocarbonyl silane as a raw material, performs alcoholysis reaction under excessive alcohol, and esterifies at low temperature to obtain the alkoxy silane with the purity of more than 98 percent.
The invention adopts urea as a proton absorbent for absorbing HCl generated by reaction, and the Cl<-> content in the product is less than 4 ppm.
Detailed description of the invention
Example one:
in a 1000ml three-necked flask reactor, 151.8g of absolute ethanol and 207g of urea were charged. Stirring, heating to 50-60 deg.C, and adding chloromethyl trichlorosilane (ClCH) dropwise into the reaction kettle2SiCl3)184.5 g. The dropping time is 1-2 hours, and the reaction temperature is controlled to be 10-60 ℃. After the end of the dropwise addition, the reaction was kept in equilibrium for 2 hours. Stopping stirring, discharging the materials into a delayer, settling for 0.5 h, discharging the lower urea salt solution to obtain the upper transparent liquid, namely the target product chloromethyl triethoxysilane [ ClCH]2SiOC2H5)3，bp186℃/700mmHg]98.11% by weight of C2H5The OH content was 0.32 and the Cl-content was 3 ppm.
Example two:
the synthesis method is the same as example one, the materials are chloromethyl trichlorosilane 184.5g, absolute ethyl alcohol 151.8g and petroleum ether 200g, the reaction time is 1.5 hours, and the balance is 2 hours. Get ClCH2SiOC2H5)3Content of 81.35%, C2H5OH content 13.72% and Cl-The content was 190 ppm.
Example three:
the synthesis method is the same as example one, the charging materials are chloromethyl trichlorosilane 184.5g, absolute ethyl alcohol 151.8g, pyridine 272.5g, the reaction time is 1.5 hours, and the equilibrium is 2 hours. Get ClCH2SiOC2H5)3Content 92.52%, C2H5OH content 3.72%, Cl-The content was 86 ppm.
Example four:
the synthesis method is the same as that in the first example, the raw materials comprise 184.5g of chloromethyl trichlorosilane, 105.6g of anhydrous methanol and 207g of urea, the reaction time is 1.5 hours, and the balance is 2 hours. Get ClCH2SiOCH3)3Content of 98.54%, CH3OH content 0.37%, Cl-The content was 3 ppm.
Example five:
the synthesis method is the same as example one, the materials are chloromethyl trichlorosilane 184.5g, anhydrous methanol 105.6g and petroleum ether 200g, the reaction time is 1.5 hours, and the balance is 2 hours. Get ClCH2SiOCH3)3Content of 82.63%, CH3OH content 14.67%, Cl-The content was 172 ppm.
Example six:
synthesis method same as example one, the charge materials are chloromethyl trichlorosilane 184.5g, anhydrous methanol 105.6g, pyridine 272.5g, reaction time is 1.5 hours, and balance iscarried out for 2 hours. Get ClCH2SiOCH3)3Content of 91.75%, CH3OH content 3.37%, Cl-The content was 79 ppm.
Claims (6)
1. An α -chlorohydrocarbonyl siloxane is prepared through alcoholysis reaction of α -chlorohydrocarbonyl chlorosilane, and features that α -chlorohydrocarbonyl siloxane is prepared from α -chlorohydrocarbonyl chlorosilane through solvent-free liquid-phase alcoholysis reaction, urea is used as proton absorbent, the mole ratio of reactants is α -chlorohydrocarbonyl chlorosilane to alcohol to proton absorbent is 1: 3.0-3.6: 3-4.5, the reaction temperature is 10-60 deg.C, the reaction time is 1-2 hr, and the balance time is 2 hr, so obtaining α -chlorohydrocarbonyl siloxane product.
2. The process of claim 1 wherein the reactant α -chlorohydrocarbylchlorosilane is structurally characterized as α -chlorohydrocarbylchlorosilaneThe formula is as follows: ClR1SiCl3In the formula, R1Is CH2Or C6H4。
3. The method of claim 1, wherein the reactant alcohol has the formula R2OH, in the formula R2Is CH3、C2H5、i-C3H7、n-C4H9、i-C4H9。
4. The method for preparing α -chloroalkyl siloxane according to claim 1, wherein the method comprises conducting alcoholysis reaction of chloromethyl trichlorosilane with absolute ethanol, using urea as HCl absorbent, wherein the molar ratio of chloromethyl trichlorosilane, ethanol and urea is 1: 3.0-3.6: 3-4.5, the reaction temperature is 10-60 ℃, thereaction time is 1.5 hours, the equilibrium time is 2 hours, the reaction product is chloromethyl triethoxysilane, and the purity is not less than 98%.
5. The method of claim 1, wherein the purity of ethanol is not less than 99.5%, and the water content is less than 0.5%.
6. The process of claim 1, wherein the proton absorbent is urea having a purity of 46.3% or more total nitrogen and less than 0.5% water.
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| CN103030809A (en) * | 2012-12-31 | 2013-04-10 | 山东大学 | Chloromethyl-containing polysiloxane and synthetic method thereof |
| CN106188123B (en) * | 2015-05-07 | 2019-02-22 | 中国石油化工股份有限公司 | A kind of chlorosilane alcoholysis plumper and its regeneration method |
| CN112110952B (en) * | 2020-10-09 | 2021-12-07 | 山东大学 | Functionalized alpha-amino triethoxysilane and preparation method thereof |
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