Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/68—Preparation of metal alcoholates
  • C07C29/70—Preparation of metal alcoholates by converting hydroxy groups to O-metal groups

Definitions

• the invention relates to a novel process for the preparation of lower aluminum alkoxide by gas-solid phase reaction.
• Lower aluminum alkoxide can be widely used in fields such as organic raw materials, pharmaceutical intermediates, catalysts, dehydrators, etc., and is also an important precursor for the preparation of advanced ceramic materials. With the development of chemical industry and pharmaceutical industry, the need for lower aluminum alkoxide is also increasing.
• the disadvantage of this technology is that, since the reactants, raw materials and the catalysts are reacted together, the lower aluminum alkoxide has to be separated from the excessive alcohol by distillation after the reaction. Moreover, the distillation operation necessarily causes a small amount of alcohol to be mixed into the final product lower aluminum alkoxide, which lowers its purity. To increase the efficiency of separation, the manufacturer often employs vacuum distillation, which not only increases the investment on equipments, but also reduces the safety factor of the production. It is also disclosed in the patent document (publication No. CN 160 076 5 A) that acetates were additionally added into the reaction as solvents, and the separation thereof required distilling for a longer period, thus further increasing the energy consumption and the production cost of the manufacturer.
• Another method for the preparation of the lower aluminum alkoxide is the alcohol displacement method.
• the lower aluminum alkoxide was prepared with the alcohol displacement method wherein aluminum ethoxide and n-butanol were employed as the raw materials which were heated to reflux in a liquid state for several hours, displacing ethanol in aluminum ethoxide with n-butanol to prepare aluminum n-butoxide. Subsequently vacuum distillation procedure was employed, wherein the reaction was terminated at the second boiling point to yield aluminum n-butoxide.
• the disadvantages of this method are: the cost is too high for using aluminum ethoxide as a raw material, and the energy consumption is very high when the alcohol and lower aluminum alkoxide are individually separated by distillation. Moreover, the catalysts of choice in conventional aluminum alkoxide preparation are mostly chlorides of mercury or iodine, which are severe pollutant to the environment.
• the invention provides a novel process for the preparation of lower aluminum alkoxide by gas-solid phase reaction which is green, safe, highly efficient and having low energy consumption. It solves the problems that, for example, the manufacture of lower aluminum alkoxide causes high costs, has complicated process, relatively low safety factor and relatively low reaction rate. Moreover, the lower aluminum alkoxide product yielded by the invention also has a high purity. BRIEF DESCRIPTION OF THE DRAWINGS
• Figure 1 the infrared spectrum of the product aluminum n-butoxide obtained in Example 1 .
• the invention provides a process for the preparation of lower aluminum alkoxide by gas-solid phase reaction, comprising reacting gaseous lower alkyl alcohol with metal aluminum.
• a process for the preparation of lower aluminum alkoxide comprising the steps of: adding the lower alkyl alcohol into a container and heating it to reflux to generate a gaseous lower alkyl alcohol;
• the lower alkyl alcohol can be a C2-C4 saturated or unsaturated alcohol, preferably a C2-C4 saturated alcohol, including ethanol, propanol, butanol, in particular butanol, preferably n-butanol.
• the lower alkyl alcohol which is in a gaseous state, is contacted with the metal aluminum and reacted.
• the metal aluminum used in this process can be in any form including aluminum ingot, aluminum flake, aluminum block, aluminum turning and aluminum slag.
• the purity of the aluminum is 99% or above.
• aluminum is excessive in stoichiometry.
• lower alkyl alcohol : aluminum is ⁇ 1 : 1 (molar ratio), preferably lower alkyl alcohol : aluminum is 1 : 3 (molar ratio), and generally between 1 : 3 and 1 : 1.
• the metal aluminum is not contacted with the liquid lower alkyl alcohol prior to the reaction.
• the metal aluminum raw material is placed above the lower alkyl alcohol and separated therefrom.
• the porous material can be any material that is inert under the reaction conditions, for example including, but not limited to various materials such as glass mesh, steel mesh, nylon mesh, etc.
• the catalyst includes any catalyst commonly used in the production of lower aluminum alkoxide, preferably a catalyst in a solid form, such as anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride catalyst.
• the catalyst can be added into the lower aluminum alkoxide, or placed on the porous material together with the metal aluminum raw material.
• the catalyst is a solid and is placed in the upper part of the container together with the aluminum raw material.
• a process for the preparation of lower aluminum alkoxide of high purity by a gas-solid phase reaction with aluminum and n-butanol used as the raw materials wherein the aluminum can be aluminum flake, aluminum block, aluminum turning or aluminum slag with a purity of 99% or more, and the aluminum has to be excessive, i.e., aluminum : n-butanol > 1 : 3 (molar ratio), generally between 1 /3 and 1 , and the process is green, safe, highly efficient and has low energy consumption.
• the n-butanol involved in the reaction is in a gaseous state rather a liquid state.
• Anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride is used as the catalyst, and 0.5 to 3 g of the catalyst per liter of n- butanol is needed.
• the specific process for the preparation of lower aluminum alkoxide of high purity by gas-solid phase reaction is as follows: firstly, n-butanol is added into the reactor, and then a porous mesh containing a mixture of aluminum and catalyst is placed above the liquid which is then heated to reflux. When the boiling point of n-butanol (for example, 1 17.73 ° C under atmospheric pressure) is reached, the evaporated gaseous n-butanol will react with the metal aluminum in the presence of the catalyst as it passes through the porous mesh, and the lower aluminum alkoxide generated will drop back into the reactor through the porous mesh. With the increase of the amount of the lower aluminum alkoxide in the reactor, the azeotropic temperature also increases.
• the aluminum involved in the reaction is excessive, and the lower alkyl alcohol is involved in the reaction in a gaseous state rather than the conventional liquid state, which contributes to the increase of reaction rate. Omission of distillation simplifies the process, reduces the energy consumption, reduces the equipment investment by the enterprise, and increases the safety of the production.
• Using anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride as the catalyst is both economical and friendly to the environment.
• the process according to the invention wherein the lower aluminum alkoxide is prepared by reacting gaseous lower alkyl alcohol with solid metal aluminum, provides the following advantages: the raw materials is easy to obtain; the process itself is safe and convenient with a simple post processing, and requires low energy consumption, reduces the intervention of other substances during the reaction, and is able to produce lower aluminum alkoxide of high purity in a way that saves energy and is economically advantageous.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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Citations (4)

• 2011
  • 2011-01-26 CN CN201110028268.2A patent/CN102153448B/zh active Active
  • 2011-09-29 WO PCT/CN2011/080380 patent/WO2012100555A1/en active Application Filing

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