RU2391332C1 - Method of obtaining manganese (ii) benzoate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of obtaining manganese (II) benzoate through direct reaction of metal with carboxylic acid in the presence of an oxidising agent, a stimulating iodine additive and a liquid phase organic solvent in a bead mill, in which the oxidising agent used is manganese peroxide taken in amount of 0.15-0.50 mol/kg, and molar ratio of metal:peroxide equal to (1.5.2.2):1; benzoic acid is taken in amount of (2,05÷2,1)·(n_Mn+

), where n_Mn and

- number of moles of metal and its peroxide in the load, the liquid phase solvent used is butylacetate and the stimulating additive of molecular iodine is taken in amount of 0.02-0.05 mol/kg; the process is started and carried out while stirring intensely and under forced cooling at temperature ranging from room temperature to 45-60°C until achieving virtually quantitative consumption of metal and its peroxide into a product, after which stirring and forced cooling of the reaction mixture are stopped, the reaction mixture is separated from the glass beads and filtered, the glass beads and reactor components are washed with a liquid phase solvent which is then taken for washing the residue on the filter, the obtained filtrate is cooled to 7-10°C and kept at that temperature for 2-2.5 hours for completion of crystallisation of the product, the suspension formed is filtered, the obtained residues of the product are separately taken for cleaning through recrystallisation, and the filtrate is returned for the repeated process. Output the extracted solid product is 87-97% of the theoretical output. A portion of the product is returned for the repeated process together the filtrate.

EFFECT: design of an improved method of obtaining manganese benzoate.

9 ex

Description

The invention relates to a technology for producing manganese (II) carboxylates and can be used in various fields of chemical practice, in conducting scientific research, as well as in analytical control.

A known method of producing manganese formate (RF patent No. 2316536, publ. 10.02.2008, BI No. 4), according to which the target salt is obtained by direct interaction of the metal and its oxide with a solution of formic acid in an organic solvent with an acid concentration of 3.5-10 , 8 mol / l and a stimulating additive of iodine in an amount of 0.025-0.100 mol / kg of the liquid phase, dosed in a mass ratio with solid reagents (4.9 ÷ 11): 1 and with glass beads 1: (1 ÷ 2). As manganese oxide, MnO ₂ , Mn ₂ O ₃ and Mn ₃ O _{4 are used} , which are taken in a molar ratio with manganese 1: (1.8 ÷ 2.2). The loading is carried out in the sequence: the liquid phase as a whole or its components, then the stimulating additive of iodine is dissolved in it, after which the metal and its oxide are introduced. Next, they include mechanical stirring in a bead mill and conduct the process in the absence of external heat supply until the oxide is almost completely consumed. After that, the process is stopped, the reaction mixture is separated from glass beads and heavy particles of unreacted metal and then filtered. The obtained precipitate of the target manganese salt is sent for purification by recrystallization, and the filtrate is returned to the repeated process.

In this case, ethyl acetate, ethylene glycol, ethyl cellosolve, 1,4-dioxane, dimethylformamide and n-butyl alcohol are used as a solvent of the liquid phase.

The disadvantages of this method are:

1. Acid is loaded with respect to the remaining reagents in a large stoichiometric excess. Formic acid is monobasic, liquid, with the smallest molecular weight for carboxylic acids, which makes it possible to take a large excess of it. In addition, it mixes well with many organic solvents. Benzoic acid is higher molecular weight, solid under ordinary conditions, moreover, it is very limited and even poorly soluble in many organic solvents. Therefore, the indicated excess for it in a homophase system is simply impossible. And the presence of a large amount of solid phase in the initial reaction mixture is very unpredictable with respect to the effect on the ongoing redox process.

, при взаимодействии которого валентное состояние марганца меняться не будет. В настоящее время нет надежных данных, чтобы сопоставить оксиды и пероксид марганца в качестве потенциальных окислителей металла и сделать определенный вывод в рассматриваемом плане.2. In the process under consideration, manganese oxidation formally occurs due to the reduction of Mn (III) and Mn (IV) compounds (manganese reducing agent, manganese (III) and (IV) oxides - oxidizing agents). It is not at all obvious that peroxide can act as a similar metal oxidizing agent.

, in the interaction of which the valence state of manganese will not change. At present, there is no reliable data to compare oxides and peroxide of manganese as potential oxidizing agents of the metal and to draw a definite conclusion in this plan.

3. Benzoic acid is slightly weaker compared to formic (pK _a 4.2 versus 3.8). It is not at all obvious how this will affect the characteristics of the gross redox processes with their participation.

Closest to the claimed, including in terms of the gross formula of the used oxidizing agent (MnO ₂ in both cases), is a method for producing manganese acetate (II) (RF patent No. 2294921, publ. 10.03.2007, BI No. 7) by direct the interaction of the oxidizing agent with metal and acetic acid in the presence of a stimulating additive of iodine in a bead mill. Accordingly, the metal and manganese dioxide are taken in a molar ratio of 2: 1 in an amount of 11.8% by weight of the liquid phase, which is based on an organic solvent (ethyl cellosolve, ethylene glycol, 1,4-dioxane, isoamyl or n-butyl alcohols) and acetic acid in an amount of 3.4-5 mol / kg The liquid phase is dosed in a molar ratio with glass beads 1: 1.5. Iodine is also dissolved in it in an amount of 0.025-0.070 mol / kg. The download is carried out in the sequence: the liquid phase or its components, iodine, metal and its dioxide. The process begins at room temperature and lead to almost complete consumption of manganese dioxide. The resulting reaction mixture is separated from glass beads and heavy particles of unreacted metal, and then sent to the filter. The precipitated salt product is purified by recrystallization, and the filtrate is recycled.

The disadvantages of this method are:

- это соединения марганца (IV), а пероксид

- соединение марганца (II). Ясно, что физические и химические свойства этих соединений должны быть разными.1, 2. Described above in paragraphs 1 and 2 in relation to the method for producing manganese formate. Acetic acid is not very different in molecular weight from formic acid and is approximately half the molecular weight of benzoic acid. Like formic acid, it is liquid. Therefore, the excess acid reagent can be large. As for the oxidizing agent, their gross formulas are the same (MnO ₂ ). But a completely different structure: dioxide

are manganese (IV) compounds, and peroxide

- compound of manganese (II). It is clear that the physical and chemical properties of these compounds must be different.

3. There is no reason to believe that the transition from acetic acid to benzoic acid will not require replacing the solvent of the liquid phase, as well as changes in the limit salt concentration in the final reaction mixture, upon reaching which the process must be stopped in order to avoid pastes and other difficultly processed systems. Therefore, initial reagent loads should be made in such a way that exceeding the permissible product content in the final reaction mixture is automatically excluded. It is clear that in the known and claimed solutions they cannot be the same.

4. In the known solution, the accumulation of the bulk of the product took place in the solid phase, which predetermined the possibility of its separation by simple filtration. It would be good if this situation would be preserved even upon receipt of manganese benzoate. But this does not mean that this will happen automatically, as there is no clarity that such an option is possible at all. All this must be proved and the conditions sought for a favorable option.

5. At the moment, there is insufficient information in the reference and periodic literature to compare the solubilities of manganese acetates and benzoates in most organic media. Therefore, it is impossible to predict the dynamics of changes in the heterophase of processes during the transition from acetic acid to benzoic. There is no way to evaluate the duration of the process in the absence of their experimental determination. Especially when replacing MnO ₂ dioxide with MnO ₂ peroxide.

The objective of the invention is to select such a solvent, the ratio of the downloads of the metal, its peroxide and acid, the downloads themselves, as well as the conditions for the production of manganese (II) benzoate, which would ensure almost quantitative conversion of all reagents to the target salt, as well as the accumulation of the bulk of the salt in solid phase of the reaction mixture, easily separated by simple filtration.

в количестве 0,15-0,50 моль/кг, а мольное соотношение металл-пероксид (1,5÷2,2):1; бензойную кислоту берут в количестве (2,05÷2,1)·(n_Mn+

), где n_Mn и

- количество молей металла и его пероксида в загрузке, в качестве растворителя жидкой фазы используют бутил-ацетат, а стимулирующей добавки - молекулярный йод в количестве 0,02-0,05 моль/кг; процесс начинают и ведут в условиях интенсивного перемешивания и принудительного охлаждения в диапазоне температур от комнатной до 45-60°C до достижения практически количественного расходования металла и его пероксида в продукт, после чего перемешивание и принудительное охлаждение реакционной смеси прекращают, реакционную смесь отделяют от стеклянного бисера и фильтруют, стеклянный бисер и элементы реактора промывают растворителем жидкой фазы, который в последующем идет на промывку осадка на фильтре, полученный фильтрат охлаждают до 7-10°C и выдерживают при такой температуре в течение 2-2,5 час для завершения кристаллизации продукта, образовавшуюся суспензию фильтруют, полученные осадки продукта направляют раздельно на очистку путем перекристаллизации, а фильтрат возвращают в повторный процесс.The problem is achieved in that as the oxidizing agent in the direct interaction of manganese with benzoic acid take manganese peroxide

in an amount of 0.15-0.50 mol / kg, and the molar metal-peroxide ratio (1.5 ÷ 2.2): 1; benzoic acid is taken in an amount of (2.05 ÷ 2.1) · (n _Mn +

), where n _Mn and

- the number of moles of metal and its peroxide in the charge, butyl acetate is used as a solvent for the liquid phase, and molecular iodine in an amount of 0.02-0.05 mol / kg is used as a stimulating additive; the process is started and conducted under conditions of vigorous stirring and forced cooling in the temperature range from room temperature to 45-60 ° C until practically quantitative consumption of the metal and its peroxide in the product is achieved, after which the stirring and forced cooling of the reaction mixture are stopped, the reaction mixture is separated from glass beads and filtered, glass beads and reactor elements are washed with a solvent of a liquid phase, which subsequently goes to wash the filter cake, the resulting filtrate is cooled to 7 -10 ° C and maintained at this temperature for 2-2.5 hours to complete crystallization of the product, the resulting suspension is filtered, the resulting precipitates of the product are sent separately for purification by recrystallization, and the filtrate is returned to the repeated process.

Characteristics of the raw materials used

Reactive manganese according to GOST 6008-90

Manganese peroxide according to GOST 4470-48

Crystalline iodine according to GOST 4159-79

Benzoic acid according to GOST 6413-77

Butyl acetate according to GOST 8981-78

The process of the claimed method is as follows. The vertical bead mill, equipped with a high-speed paddle-type stirrer, a cooling jacket with cold running water as a cooling agent and a reflux condenser, introduces the calculated quantities of glass beads, a solvent of the liquid phase, stimulating additives of iodine, benzoic acid. Mechanical stirring is switched on and acid and additives are dissolved for some time. Then, manganese and its peroxide are introduced and this moment is taken as the beginning of the process. The reactor is cooled immediately by adjusting the feed rate of cold water so that the temperature in the reaction zone does not exceed 45-60 ° C. During the process, samples are taken of the reaction mixture, in which the content of the accumulated salt of manganese is determined, as well as the residual amounts of the metal, its peroxide and benzoic acid. This makes it possible to timely determine the moment of termination of the redox process (the residual contents of the metal and its peroxide tend to zero).

At the end of the process, stirring in a bead mill and its cooling are stopped, the reactor vessel with the reaction mixture and glass beads is disconnected from the lid with a stirrer and removed from a special socket of the frame frame. The contents of the reactor are poured into the receiving tank of the filtering unit with a mesh with mesh sizes of 0.3 × 0.3 mm as a filter membrane. Here, the reaction mixture is separated from glass beads. Next, the glass beads are removed from the filter septum and returned to the reactor. The latter is placed in a socket intended for it in the frame frame of the installation and connected to the cover. The calculated amount of the solvent of the liquid phase is poured, stirring is included, and the beads and reactor elements are washed from the residual reaction mixture. Stirring is stopped, the reactor is again removed from its workplace, and its contents are separated from the glass beads, as noted above.

The reaction mixture freed from beads is sent for filtration. The solid phase suspended in the liquid is separated, which is washed with a solvent after washing the beads and the reactor from the residues of the reaction mixture. The beads are sent to prepare for the second process, and the filtrate and the washing solvent are cooled to 7-10 ° C and held at this temperature for a certain time, sufficient to complete crystallization of the product under such conditions. The precipitated solid phase is filtered off, removed from the filter and sent for purification by recrystallization. It usually makes no sense to mix it with the initially filtered solid phase, since the former is contaminated by the mechanical wear products of the plastic blades of the mechanical stirrer. Therefore, it makes sense to carry out the cleaning of the separated solid precipitates of the product separately.

The filtrate obtained during the second filtration is returned to the loading of the repeated process.

Example No. 1

Into a vertical bead mill with a case in the form of a glass with a flat bottom made of thick-walled glass with an inner diameter of 52.8 mm and a height of 141 mm with a cooling jacket over almost the entire height of the body and under the bottom of the glass, equipped with a high-speed mixer with a rectangular plexiglass blade of size 50 × 46 mm and a thickness of 3.8 mm, as well as a reflux condenser with running water as a cooling agent, sequentially load 145 g of glass beads, 59.03 g of butyl acetate as a solvent of the liquid phase, 30.74 g of benzoic acid and 1.27 g of iodine as a stimulant. Mechanical stirring is turned on and a solution of a suspension of benzoic acid and a stimulating additive of iodine is prepared for 5 minutes. After that, without stopping mixing, 4.40 g of manganese and 4.56 g of manganese peroxide MnO ₂ · 1,5H ₂ O are introduced. The last moment is taken as the beginning of the process. Flowing cooling water is immediately supplied to the reactor jacket and to the reflux condenser. During the process, samples are taken of the reaction mixture, in which the content of the accumulated salt of manganese (II) is determined, as well as the residual contents of the metal, peroxide and benzoic acid. These data determine the time to reach 25, 50, 75 and more than 97% yield of manganese benzoate from the calculated value. In this example, it was 5, 12, 20, and 40 minutes, respectively. The temperature of the reaction mixture at these points was 49, 54, 58, and 60 ° C.

After 45 minutes from the beginning of the process, it is stopped. To do this, stop mechanical stirring and stop supplying water to the cooling jacket and reflux condenser. The reactor is disconnected from the lid associated with the reflux condenser and containing the stuffing box of the mechanical mixer, as well as the loading hatch and the nests for the sampler and temperature measuring device, and then they are removed from the corresponding socket of the frame frame so that the reaction mixture could be removed from the mixer and its shaft drain into the reactor zone, which takes about 3 minutes. After that, the contents of the reactor are poured into a receiving funnel of the filtering unit with a mesh with mesh sizes of 0.3 × 0.3 mm as a filter partition. The reaction mixture (suspension of salt in solution) at a temperature of 57 ° C falls by gravity into a collection tank, and glass beads with the remains of the reaction mixture remain on the grid. It is carefully removed from the grid and returned to the reactor, which is put in its place in the frame frame and connected to the lid. 40 g of butyl acetate are charged into such an assembled reactor and stirring is continued for 5 minutes.

In parallel, the suspension from the collection tank is filtered at a temperature of 50 ° C, and the tank itself is returned to its original place.

Stirring of the washing solvent is stopped, the reactor is removed, and its contents are poured into a receiving funnel with a mesh as a filter screen. The washed beads from the net are returned to the reactor for a second process. A washing solvent is used to wash the filter cake. At the end of this operation, the washed salt precipitate is removed from the filter and sent for purification by recrystallization. With this cleaning, solid products of mechanical destruction of the plastic blades of the mechanical stirrer are also removed.

The collected filtrate and washing solvent are cooled to a temperature of 8.5 ± 0.1 ° C and incubated for 2 hours. The crystallized manganese (II) benzoate is filtered off and then dried. And the obtained filtrate containing excess acid, the products of the transformation of the stimulating additive and the dissolved manganese benzoate are sent to download the second process.

The yield of product separated by filtration was 93% of the calculated value with practically quantitative consumption of metal and its peroxide in the target product. The difference is due to losses during the separation of the reaction mixture and return with the filtrate to the repeated process.

Examples No. 2-9

Reactor, initial reagents, liquid phase solvent, stimulating iodine additive, loading mass and its ratio with the mass of glass beads, the order of loading of reagents, the process, monitoring the progress of the process, the moment of termination of the process, the procedure for separating the reaction mixture from glass beads, removing residual reaction mixtures with beads and reactor elements, isolating and purifying the product, and returning the filtrate and the washing solvent to a repeated process are similar to those described in Example 1.

They differ in the initial content of manganese peroxide in the initial load, the ratio of metal: peroxide; excess benzoic acid, the content of the stimulating additive of iodine, the upper limit of the temperature range in which the redox process takes place, as well as the cooling temperature of the filtrate and the washing solvent and the duration of crystallization of manganese benzoate. The indicated differences and the obtained process characteristics are given in table. (PC is a reaction mixture).

Characteristics of loading, process, isolation and product yield Example No. 2 3 four 5 6 7 8 9 The initial content of peroxide, mol / kg 0.15 0.20 0.30 0.40 0.40 0.40 0.40 0.50 The initial ratio of molar contents of metal: peroxide (mol: mol) 2: 1 2: 1 2: 1 1.5: 1 1.7: 1 1.9: 1 2.21 2: 1 The initial content of iodine, mol / kg 0,03 0.02 0.04 0.05 0.05 0.05 0.05 0.05 The amount of loaded benzoic acid, mol / kg 0.95 1.26 1.89 2.20 2,31 2.46 2.74 3.24 Temperature at the time of loading reagents, ° C eighteen eighteen eighteen 19 19 twenty twenty twenty The time for preparation of the initial solution of benzoic acid, min four four four 5 5 6 6 8 Time (min) to reach the product yield from the calculated value,% 25 8 10 7 6 5 four 6 10 fifty 17 22 fifteen 13 12 eleven fourteen twenty 75 42 51 35 22 21 twenty 25 thirty > 98 77 105 59 48 46 38 52 49 Temperature (° C) PC at the time of reaching the outputs (in%) 25 38 36 44 46 47 52 47 52 fifty 45 46 49 52 55 60 54 59 75 40 44 51 55 56 59 60 60 > 98 37 40 fifty 55 56 57 60 60 The duration of the process, min 84 111 66 53 fifty 42 57 55 Wash solvent,% by weight of PC thirty 35 35 40 40 40 40 fifty PC temperature (° C) at the time of separation of the beads 34 36 44 51 49 fifty 55 57 at the time of filtering thirty thirty 38 41 40 43 47 47 The temperature of the 1st filtrate in a mixture with a washing solvent after cooling, ° C 10 7 8 9 8 8 8 9 The exposure of the cooled mixture of the filtrate and the washing solvent before filtration, ° C 2 2 2 2,3 2,4 2,3 2.5 2.5 The output of the separated solid manganese benzoate,% of theoretical value 87 89 90 91 92 93 95 97

The positive effect of the invention

1. The process is carried out under mild temperature conditions, supported by reaction heat. The organization of forced cooling is not very difficult. The cooling agent is running water, which can be used in a closed cycle.

2. The bulk of the product accumulates in the solid phase in the form of a suspension and is subsequently separated by simple filtration.

3. Used solid reagents (manganese and its peroxide) are almost completely converted into a salt product, which eliminates the need for their separation from the final reaction mixture, as well as in the subsequent purification of the product from them. A small excess of acid, together with the solvent of the liquid phase and the dissolved product - salt, returns to the repeated process many times without any concentration and separation of such a solution. As a result, the yield of the separated product increases with an increase in the initial loading of the metal and peroxide, as well as the overall load.

4. During the process there are no volatile environmental pollution and wastewater.

5. The hardware design of the process is simple. It does not have boiler surveillance equipment. Simple and control over the course of the process. The moment of termination of the process is determined simply and reliably.

Claims (1)

A method of producing manganese (II) benzoate by direct interaction of a metal with a carboxylic acid in the presence of an oxidizing agent, a stimulating additive of iodine and an organic solvent of a liquid phase in a bead mill, characterized in that 0.15-0.50 mol / manganese peroxide is taken as an oxidizing agent / kg, and the molar ratio of metal peroxide (1.5 ÷ 2.2): 1; benzoic acid is taken in an amount of (2.05 ÷ 2.1) · (n _Mn +

), where n _Mn and

- the number of moles of metal and its peroxide in the load, butyl acetate is used as the solvent of the liquid phase, and molecular iodine in the amount of 0.02-0.05 mol / kg as a stimulating additive; the process is started and conducted under conditions of vigorous stirring and forced cooling in the temperature range from room temperature to 45-60 ° С until the practically quantitative consumption of metal and its peroxide in the product is achieved, after which the stirring and forced cooling of the reaction mixture are stopped, the reaction mixture is separated from glass beads and filtered, glass beads and reactor elements are washed with a solvent of a liquid phase, which subsequently goes to wash the filter cake, the resulting filtrate is cooled to 7-10 ° C and kept at this temperature for 2-2.5 hours to complete crystallization of the product, the resulting suspension is filtered, the resulting precipitates of the product are sent separately for purification by recrystallization, and the filtrate is returned to the repeated process.