JP2016160202A - Method for producing and purifying bis-(2,2-dinitropropyl)acetal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing BDNPA having high safety and a high recovery rate.SOLUTION: There is provided a method for producing bis-(2,2-dinitropropyl)acetal by continuously reacting a mixture solution of (A) 2,2-dinitropropanol and (B) an acetaldehyde source in the presence of (C) an acid in a flowing passage of a flow-through type reactor, where the (C) acid is a solid acid disposed in the flowing passage, the reaction temperature in the flowing passage is 0 to 50°C, the mixing ratio (molar ratio) of the component (A) to the component (B) (where the component (B) is expressed in terms of acetaldehyde) is 0.5 to 1.0 and a polar solvent is not used as the reaction solvent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing and purifying bis- (2,2-dinitropropyl) acetal (BDNPA) used as an energy plasticizer for bullet propellants and explosives. .

  The energy plasticizer has the characteristics that the energy plasticizer itself can generate high energy in addition to the general plasticizer properties such as increasing the flexibility of the explosive composition and facilitating processing. It is used as a plasticizer for propellants and explosives.

  In general, an energy plasticizer having a nitro group is suitable for use in explosives and the like because of the high energy produced. Among them, BDNPA has a feature that the melting point is lowered by mixing with chemically similar bis- (2,2-dinitropropyl) formal (BDNPF) at a ratio of 50:50 wt%. Therefore, it can be stored and operated at a lower temperature, and safety during handling can be improved. Therefore, it is widely used for LOVA-type propellants and PBX explosives. (Non-Patent Documents 1 and 2)

  Research on production of BDNPA and BDNPF has started in the early 1960s, and a batch-type production method of BDNPA and BDNPF using a sulfuric acid or boron fluoride ether complex without using a solvent has been developed. (Patent Documents 1 and 2)

US Pat. No. 5,648,556 US Pat. No. 5,449,835

Renato R., Donald A. Geiss, Jr., Hitoshi M., (2000), BDNPA / BDNPF Shows Long-Term Aging Stability, IM / EMTechnology Implementation in the 21st Century, Presented to National Defense Industrial Association. Arthur, P., (2000), Energetic Polymers and Plasticisers for Explosive Formulations -A Review of Recent Advances, DSTO (Defence Science and Technology Organization) -TR-0966

  Bis- (2,2-dinitropropyl) acetal (BDNPA) containing four nitro groups per molecule has a high explosiveness compared to general organic compounds, so when mass-produced at once in batch mode. Raises safety concerns. Therefore, it is assumed that BDNPA is manufactured little by little in a continuous manner in order to enhance safety. However, in the case of a synthesis method using a Bronsted acid catalyst such as sulfuric acid, a side reaction caused by the acid catalyst is unavoidable, and the catalyst is neutralized with a basic substance such as caustic soda. It takes a long time in the process to perform, and it is highly possible that BDNPA is hydrolyzed. As a result, the recovery rate of BDNPA may be greatly reduced.

  In addition, when a flow reactor is used for mixing and reaction of a plurality of liquids, it is important to introduce raw materials into the reactor according to the set reaction ratio, and strict flow rate control by operating the pump is important. It is essential. In particular, in the case of using a flow reactor characterized by a minute reaction volume called a microreactor, since the volume of the reactor is very small, more strict flow rate control is required. However, sulfuric acid, which is a representative example of a Bronsted acid catalyst, has a high viscosity and a melting point near zero degrees, so that it is likely to precipitate under low temperature conditions, and it is difficult to perform stable liquid feeding with a pump. Also, in the case of a flow-type reactor, problems such as channel blockage may occur, so PID control, which is frequently used in batch-type reactor input amount control, can be used to control the outflow amount and the pumped liquid amount. Can not.

  In addition, Bronsted acid catalysts such as sulfuric acid are highly corrosive to metals and plastic materials, requiring corrosion resistance of pumps and reactor materials, reducing the choice of reactor materials and packing.

  Therefore, the present invention solves the above-mentioned problems, and increases the safety at the time of production of bis- (2,2-dinitropropyl) acetal with high risk and eliminates the need for a neutralization step. An object of the present invention is to provide a production method and a purification method capable of increasing the recovery rate.

  In the present invention, the present invention relates to a bis-reactant in which a mixture of (A) 2,2-dinitropropanol and (B) an acetaldehyde source is continuously reacted in the presence of an acid in the flow path of the flow reactor. In the method for producing (2,2-dinitropropyl) acetal, the (C) acid is a solid acid disposed in the flow path, and a reaction temperature in the flow path is 0 to 50 ° C. The mixing ratio (molar ratio) of the component (A) and the component (B) (wherein the component (B) is acetaldehyde equivalent) is (B) / (A) = 0.5 to 1.0, A polar solvent is not used as a reaction solvent.

  The solid acid may be a cationic ion exchange resin.

  The solid acid may be a solid superacid.

  The solid superacid may be a “copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether]”.

  The reaction solvent may be a nonpolar solvent.

  The nonpolar solvent may be methylene chloride.

  The present invention may include a step of continuously removing a by-product from the reaction solution by passing the reaction solution obtained by the production method through a column packed with synthetic zeolite.

  In the present invention, “OO to XX” indicating a numerical range is a concept including numerical values of the lower limit (OO) and the upper limit (XX). Therefore, if it is expressed accurately, it will be “XX or more and XX or less”.

  According to the present invention, since a solid acid is used instead of a liquid catalyst such as sulfuric acid, the possibility of a side reaction in the BDNPA synthesis reaction is low, the decomposition of the produced BDNPA can be reduced, and the neutralization step can be omitted. Thus, BDNPA can be obtained with a higher recovery rate. In addition, the adoption of the continuous method makes it easy to adjust the amount of BDNPA produced and eliminates the need to mass-produce highly explosive BDNPA at a time, thus improving safety.

It is the schematic of a flow-type reactor. It is the schematic of a flow-type reactor provided with the column filled with the synthetic zeolite.

Hereinafter, the present invention will be described in detail. In the present invention, in the absence of a polar solvent, the (D _AB ) mixture of (A) 2,2-dinitropropanol (DNPOH) and (B) acetaldehyde source is continuously contacted with (C) the solid acid. . Thereby, as shown in the following formula 1, two molecules of (A) 2,2-dinitropropanol and (B) one molecule of acetaldehyde generated from an acetaldehyde source were coupled, and high-purity bis- (2, 2-Dinitropropyl) acetal (BDNPA) can be produced continuously.

<(A) 2,2-dinitropropanol>
(A) 2,2-dinitropropanol (DNPOH) is not particularly limited in its production method, but the purity (GC purity) determined by gas chromatography (GC) is 80% or more and contains as little water as possible. Is desirable. This is because the reaction of synthesizing BDNPA is hindered by impurities and moisture contained therein, resulting in a problem of a decrease in recovery rate.

<(B) Acetaldehyde source>
(B) The acetaldehyde source may be acetaldehyde at the time of reaction, and examples thereof include acetaldehyde, paraaldehyde, and metaaldehyde. Here, since acetaldehyde has a boiling point of 20 ° C. and is easily vaporized even at room temperature (room temperature), it is necessary to always assume the problem of volatilization into the gas phase. In addition, metaaldehyde has a relatively large molecular weight and a boiling point of 246 ° C., but has a melting point of 115 ° C., and the solution tends to have a high viscosity at room temperature (room temperature) and a solid is likely to precipitate. For this reason, problems such as closing of the flow path in the reactor may occur. On the other hand, paraaldehyde has a boiling point of 124 ° C. and is liquid at ordinary temperature (room temperature). Therefore, volatilization to the gas phase as seen with acetaldehyde, or higher viscosity of the solution as seen with metaldehyde and solids (B) is most preferable as an acetaldehyde source.

この時、上の平衡はＨＢ（酸点）のプロトンを与える能力（酸強度）が高ければ右に寄り、中間体の量が増加することによって、反応全体の反応速度が速くなる。酸強度は、一般的にハメットの酸度関数で表される。 <(C) Solid acid>
In the present invention, the (C) solid acid is a solid that performs the same catalytic action as hydrogen ions in a liquid-phase homogeneous catalytic reaction, and is a substance whose surface is acidic. As the solid acid, silica-alumina, which is a mixed gel of silicon oxide and aluminum oxide, has been used for a long time. Here, since the reaction using a solid acid is caused by a direct interaction between the substrate (acid point, generally active site) showing acidity existing on the surface of the solid acid, the substrate is an acid. When adsorbed on a point, it receives a proton and changes to a reaction intermediate (see the following formula 2).

At this time, the above equilibrium is shifted to the right if the ability to give HB (acid point) protons (acid strength) is high, and the amount of intermediate increases, so that the reaction rate of the whole reaction increases. The acid strength is generally expressed by Hammett acidity function.

  In the present invention, since the target product BDNPA is an energy plasticizer used for explosives and the like, it is preferable to use a polymer solid acid having relatively soft physical properties (Mohs hardness ≦ 3.5). When a solid acid (Mohs hardness> 3.5) derived from mineral is used, if the solid acid is mixed in the explosive composition produced using BDNPA obtained by the reaction, impact such as dropping or friction As a result, cleavage and shearing of the solid acid occur, and the explosive composition as a whole is likely to be sharpened and is dangerous.

Examples of the solid acid (C) used in the present invention include cationic ion exchange resins. In particular, a cationic ion exchange resin obtained by radical copolymerization of styrene and divinylbenzene and reacting fuming sulfuric acid to introduce a sulfonic acid group into an aromatic ring is desirable. Cationic ion exchange resins can be synthesized by suspending the base copolymer of styrene and divinylbenzene in water to obtain polymers with various particle sizes, and the surface area per unit volume. It is easy to change the ratio. In addition, the introduction of the sulfonic acid group by fuming sulfuric acid described above can change the amount of the sulfonic acid group per unit area relatively freely, so that the acid strength of the surface of the cationic ion exchange resin can be changed. Can be easily performed. Sealed filling and sealing a cationic ion exchange resin in a tubular reactor, the reaction with (A) 2,2-dinitro-propanol and (B) of acetaldehyde source (D _AB) of the mixed solution to flow into the reactor Can be performed. In this case, since the particle size (surface area) of the ion exchange resin and the acid strength of the surface have a high degree of freedom in selection, the degree of freedom in designing the reactor according to the production scale becomes extremely high. It is preferable that the surface area per unit volume is large and the ion exchange amount indicating the proton release amount per unit area is large because the reactor can be made compact. On the other hand, in order to perform the reaction efficiently, it is necessary to suppress local heat generation or resistance to the fluid accompanying the reaction within an allowable range. Therefore, the cationic ion exchange resin used as the solid acid has, for example, an apparent density of 600 (g / L) when dried, a total ion exchange capacity of 4.7 (eq / L), and an average surface area of 45 (m ² / g). ), An ion exchange resin for catalyst “Amberlyst 15DRY”, an apparent density of 805 (g / L), a total ion exchange capacity of 2.05 (eq / L), and a particle size range of 300 to 1180 (μm). An ion exchange resin “DIAION PK228” or the like is desirable.

Moreover, you may use the solid super strong acid classified into a super strong acid as (C) solid acid in this invention. The super strong acid is an acid having an acid strength stronger than that of 100% sulfuric acid, and is an acid having a Hammett acidity function (H0) smaller than -11.93. Examples of the solid superacid that can be used in the present invention include a copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether]. Specific examples thereof include, for example, “Aldrich” Nafion NR50 ". “NafionNR50” is a bead shape having rubber elasticity, and has less flexibility in particle size and acid strength than ion exchange resin, but because of its molecular structure, a sulfonic acid group is bonded to a linear aliphatic chain. It has a feature that acid strength is stronger than that of a functional ion exchange resin. This “NafionNR50” has an ion exchange capacity of 0.8 (meq / g), a particle size of 7-9 (mesh) of 3 mm × 4 mm, and a relative specific gravity of 2.1 (g / mL). Further, as the solid superacid, “Nafion SAC-13” in which the reaction efficiency of “NafionNR50” is improved is more preferable. “Nafion SAC-13” has a surface area that is 10,000 times larger than that of “NafionNR50” alone by supporting “NafionNR50” on an amorphous silica surface, thereby improving the reaction efficiency. “Nafion SAC-13” has a surface area of 200 (m ² / g) or more, a fine pore diameter of 10 (nm) or more, a porosity of 0.6 (ml / g) or more, and a relative specific gravity of 2.1 (g / ml). ).

<(D _AB ) mixture>
The (D _AB ) mixed solution of (A) 2,2-dinitropropanol and (B) acetaldehyde source may be prepared in advance, or immediately before being fed to the flow reactor (A) 2, 2 -Dinitropropanol and (B) acetaldehyde source may be mixed. The mixing ratio (molar ratio) of (A) 2,2-dinitropropanol and (B) acetaldehyde source is 0.5 to 1 (B) / (A) (wherein component (B) is converted to acetaldehyde). 0.0, and a range of 0.7 to 0.8 is preferable considering the influence of gasification and aeration of the acetaldehyde source. When (B) / (A) is greater than 1.0, by-products are predominantly produced in the BDNPA synthesis reaction. On the other hand, when (B) / (A) is smaller than 0.5, (A) 2,2-dinitropropanol is excessive, and unreacted (A) 2,2- Since dinitropropanol remains, the recovery rate of BDNPA decreases. Since (A) 2,2-dinitropropanol remaining in the reaction solution cannot be easily removed, the case where (A) 2,2-dinitropropanol remains is compared to the case where excess acetaldehyde remains. The burden on the removal process, which is a subsequent process, increases.

<Reaction solvent>
In the present invention, the reaction can be carried out without using a solvent, but the reaction may be carried out in the presence of a solvent for stabilizing the process by making the exothermic reaction uniform, that is, the reaction solvent. The reaction solvent is not particularly limited as long as it is a nonpolar solvent in which (A) 2,2-dinitropropanol as a raw material and (B) acetaldehyde source and BDNPA as a product are dissolved. It can be appropriately selected and used. Non-polar solvents with low water compatibility can separate by-product water from the raw materials and products during the reaction, thus improving the conversion rate of raw materials to BDNPA and suppressing hydrolysis of BDNPA after reaction It is possible and preferable. The nonpolar solvent used preferably has a relative dielectric constant of 20 or less, particularly an aliphatic water-insoluble solvent such as hexane or cyclohexane, an aromatic water-insoluble solvent such as benzene or toluene, methylene chloride, Chlorine solvents such as chloroform and carbon tetrachloride, water-insoluble ether solvents such as diethyl ether, t-butyl ether and cyclopentyl hexyl ether, and water-insoluble ester solvents such as ethyl acetate and butyl acetate are suitable. The reaction solvent (C) will not interfere with use unless it decomposes upon contact with a solid acid, but it is not water-soluble such as chlorinated solvents such as methylene chloride, methyl tertiary butyl ether, ethyl tertiary butyl ether, and cyclopentyl methyl ether. A water-insoluble ester solvent such as an ether solvent, ethyl acetate, or butyl acetate is preferable because (A) 2,2-dinitropropanol and (B) acetaldehyde source and product BDNPA are highly soluble. On the other hand, when a polar solvent is used, since the purity and recovery rate of BDNPA obtained by the reaction are lowered, it cannot be used as a reaction solvent.

<Production method of BDNPA>
Actual reaction, using flow reactor to be described later, (A) 2,2-dinitro-propanol and (B) acetaldehyde source and the (D _AB) distribution channels a mixed solution (C) the solid acid is located The reaction is carried out continuously to obtain BDNPA represented by the above formula 1.

<Reaction temperature>
The reaction temperature is 0 ° C. to 50 ° C., preferably in the range of 15 ° C. to 30 ° C. When the reaction temperature is lower than 0 ° C., the viscosity of the reaction solution rises and it becomes difficult to perform stable charge management. When the temperature is higher than 50 ° C., the decomposition reaction of BDNPA becomes dominant, the acetal skeleton of the generated BDNPA is easily destroyed, and the recovery rate of BDNPA is lowered. The reaction is left to adjust (D _AB) of the mixed solution (C) for starting immediately after the solid acid flows into the arranged circulation path, before feeding the (D _AB) mixture to the desired reaction temperature It is preferable.

<Reaction time>
In general, in the case of a continuous reaction, the raw material is sent from the raw material tank through the use of a pump or the air pressure of the raw material tank to flow into the reactor, and the reaction is terminated while proceeding in the reactor flow path. . In the reaction of (A) 2,2-dinitropropanol and (B) acetaldehyde source-derived acetaldehyde in the present invention, (A) 2,2-dinitropropanol and (B) acetaldehyde source flowing into the flow reactor While the (D _AB ) mixed liquid passes through the flow path of the flow reactor, the reaction time and flow rate are such that the reaction is completed by contacting with the (C) solid acid disposed in the flow path. Is set. In addition, since by-product water is generated by the reaction, the decomposition reaction of the acetal skeleton of the generated BDNPA proceeds in the presence of a solid acid. Therefore, it is not preferable to keep the (D _AB ) mixed solution of (A) 2,2-dinitropropanol and (B) acetaldehyde source in the reactor for an excessively long time.

<Method for purifying BDNPA>
The reaction liquid containing BDNPA obtained by the reaction represented by the above formula 1 is cooled and extracted into an organic layer using an organic solvent. The organic solvent used in this case is not particularly limited as long as it is not mixed with water, but is not limited to chlorine solvents such as methylene chloride, water-insoluble ether solvents such as methyl-t-butyl ether, ethyl-t-butyl ether, cyclopentyl methyl ether, and acetic acid. Water-insoluble ester solvents such as ethyl and butyl acetate are suitable because they dissolve the target BDNPA very well, and they all have a boiling point of 100 ° C. or lower when the solvent after extraction is distilled off. Particularly preferred.

  The organic solvent after extraction is washed with distilled water, and water remaining in the organic layer is removed using a dehydrating agent. As the dehydrating agent, anhydrous magnesium sulfate or calcium chloride is preferable. The water dehydrating function is not particularly limited, but it is necessary not to induce specific interaction or degradation with the synthesized BDNPA.

  In addition, the reaction solution obtained by the reaction shown in the above formula 1 is continuously passed through a column filled with an adsorbent such as synthetic zeolite to extract reaction by-products before extraction with an organic solvent. You can also Here, the by-products are water generated when bis- (2,2-dinitropropyl) acetal is synthesized, a dimer of acetaldehyde as a residual raw material, a trimer of acetaldehyde, and 2,2 -Refers to hemiacetal etc. which 1 molecule of dinitropropanol and 1 molecule of acetaldehyde reacted. The adsorbent is preferably a synthetic zeolite that can remove other by-products in addition to the dehydrating action, and examples thereof include molecular sieve 13X and molecular sieve 5A.

  High-purity BDNPA can be obtained by distilling and concentrating the organic solvent after extraction containing BDNPA thus obtained. The method of concentration by distillation is not limited to simple distillation concentration or evaporator concentration because the kettle residue is BDNPA. In order to completely remove the aforementioned organic solvent, it is necessary to adjust the pressure range from about 50 to about 200 hPa in a temperature range of about 40 to about 70 ° C. Also, from the standpoint of industrial safety, nitrogen replacement is completely performed by bubbling the solution before heating, and nitrogen is introduced into the system to reduce side reactions and the like when returning to normal pressure after completion of decompression. Things are preferable.

<Flow reactor>
An example of a flow reactor will be described with reference to FIGS.

As shown in FIG. 1, the tank 1 is connected to the reactor 3 via a pump 2 and a pipe 4 that is a raw material supply channel, and the reactor 3 is connected to a recovery unit 6 via a pipe 5. ing. In the tank 1, a (D _AB ) mixed solution of (A) 2,2-dinitropropanol and (B) acetaldehyde source is stored and sent to the reactor 3 by the pump 2. The (D _AB ) mixed solution sent to the reactor 3 is in contact with the (C) solid acid disposed in the flow path of the reactor 3 and the reaction proceeds at a predetermined temperature. It flows out to the collection unit 6 through the pipe 5. The recovery unit 6 stores a liquid separated into two layers of an organic solvent in the upper layer and an aqueous solution in the lower layer, and the reaction solution is allowed to flow into the lower layer while cooling and stirring to 1 to 5 ° C. It can extract in the organic solvent which is an upper layer. The liquid temperature in the apparatus is strictly controlled, and the liquid temperature in the flow path is confirmed by a thermocouple attached to each part.

  In addition, as shown in FIG. 2, an adsorbent column 7 can be arbitrarily provided in the middle of the pipe 5. The adsorbent column 7 is filled with an adsorbent such as a synthetic zeolite, and by-products such as water contained in the reaction liquid can be removed by passing the reaction liquid through the adsorbent column 7.

  In addition, when the diameter of the flow path of the reactor 3 and the flow paths such as the pipes 4 and 5 is reduced, the ratio of the surface area of the flow path inner surface to the inner product of the flow path is increased. Therefore, by configuring the flow path with a thin tube, the ratio of the surface area increases, and temperature control from the outside can be easily and quickly performed.

In the synthesis of BDNPA of the present invention, since (C) the solid acid contributes to the generation and decomposition of BDNPA, very strict temperature control and residence time control are required. Therefore, the diameter of the flow path is preferably set to around the millimeter size or less in order to facilitate temperature control and residence time control, and it is more preferable to use a flow microreactor set to around micrometer. In addition, in order to increase the contact area of (C) the solid acid to the (D _AB ) mixed solution of (A) 2,2-dinitropropanol and (B) acetaldehyde source, (C) the particle size of the solid acid Is preferably reduced. When problems such as local excessive heat generation and flow path clogging occur by reducing the diameter of the flow path and the particle size of the solid acid (C), inert glass, Teflon (registered trademark) beads, etc. It is desirable to mix (C) with a solid acid. It is possible to disperse heat generated by beads, etc., and to suppress local excessive heat generation. (C) When an ion exchange resin or the like is used as the solid acid, it swells when it comes into contact with the above-mentioned solvent or raw material. However, mixing the beads and the like with (C) the solid acid suppresses the rate of increase in volume and prevents the channel from being blocked.

  When a solid acid is used as a catalyst in a batch reactor equipped with a stirrer, (A) 2,2-dinitropropanol, (B) acetaldehyde source, and ( B) Acetaldehyde generated from an acetaldehyde source may diffuse into the gas phase. On the other hand, in the flow type reactor, since the gas phase portion inside the apparatus is remarkably small as compared with the batch type reactor equipped with a stirrer, (A) 2,2-dinitropropanol, (B) acetaldehyde source, And (B) Volatilization of the acetaldehyde generated from the acetaldehyde source into the gas phase can be significantly suppressed, and as a result, a decrease in the recovery rate of BDNPA can be suppressed.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the recovery rates (%) in the following examples and comparative examples are values obtained by the following formula 3.
{Recovered bis- (2,2-dinitropropyl) acetal (mol) / 2,2-dinitropropanol fed to the reactor (mol) × 1/2} × 100 (Formula 3)

(Example 1-1)
Using the experimental apparatus shown in FIG. 1, BDNPA was synthesized in a continuous manner. For the pipes 4 and 5, SUS316 ID (inner diameter) 1.0 mm was used for all. In tank 1, 14 mL of (D _AB ) mixed solution of (A) 2,2-dinitropropanol and (B) paraaldehyde (component (A) 85 mmol, component (B) acetaldehyde converted value 68 mmol, mixing ratio (molar ratio) ( B) / (A) = 0.8) was charged, and 4.2 g of Amberlyst 15DRY (Mohs hardness 3.0) manufactured by Organo Corp. was charged into the reactor 3 (ID 10 mm × L 98 mm). The mixture (D _AB ) was fed at a flow rate of 0.10 mL / min for 100 minutes using the pump 2, and reacted at a reaction temperature of 20 ° C. while passing through the reactor 3. Then, 5.0 m is passed through the pipe 5 at 1 ° C., and the recovery unit 6 containing 20 mL (upper layer) of methyl-t-butyl ether (MTBE) and 5 mL (lower layer) of distilled water is cooled and stirred to 1 to 5 ° C. It was drained to the lower layer. The lower layer of the solution obtained in the recovery unit 6 was removed and dehydrated using 1.0 g of anhydrous magnesium sulfate. The obtained extract was dried at 70 ° C. or less and a pressure of 200 hPa or less for about 15 minutes to distill off the solvent, and bis (2,2-dinitropropyl) having a purity (GC purity) of 95% as determined by GC. ) Acetal was obtained (recovery rate 38%).

(Example 1-2)
Except that the reactor 3 was charged with 3.4 g (filling ratio: 27%) of Nadion SAC13 (Mohs hardness of 3.5) manufactured by Aldrich, under the same conditions and procedure as in Example 1-1, bis- (2,2 -Dinitropropyl) acetal was synthesized in a continuous manner.

(Example 1-3)
Except that the reactor 3 was charged with 14.1 g (filling rate 68%) of Nafion NR50 (Mohs hardness 1.5) manufactured by Aldrich, which was swollen with methyl-t-butyl ether (MTBE). Under the same conditions and procedure as in 1, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner.

(Example 1-4)
A bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that the reaction temperature in the reactor 3 was 1 ° C.

(Example 1-5)
A bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that the reaction temperature in the reactor 3 was 40 ° C.

(Example 1-6)
(D _AB ) Continuous bis- (2,2-dinitropropyl) acetal under the same conditions and procedures as in Example 1-1 except that the mixing ratio (B) / (A) of the mixed solution was 0.5. Synthesis by the method was performed.

(Example 1-7)
The reactor 3 was charged with 3.4 g (filling ratio: 27%) of Nafion SAC13 (Mohs hardness 3.5) manufactured by Aldrich, and the mixing ratio (B) / (A) of the (D _AB ) mixed solution was 0.5. A bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that.

(Example 1-8)
(D _AB ) Continuous bis- (2,2-dinitropropyl) acetal under the same conditions and procedure as in Example 1-1 except that the mixing ratio (B) / (A) of the mixed solution was 1.0. Synthesis by the method was performed.

(Comparative Example 1-1)
A 10 mL test tube was charged with (A) 8.5 mmol of 2,2-dinitropropanol, (B) 6.8 mmol of paraaldehyde (acetaldehyde equivalent) and 0.79 g of Amberlyst 15DRY made by Organo Corporation, and using a magnetic stirrer. The stirrer was rotated at about 300 rpm, and reacted for 1 hour at a reaction temperature of 20 ° C. in a nitrogen atmosphere. Thereafter, the Amberlyst 15DRY is filtered and subjected to extraction, washing, and drying after-treatment under the same conditions as in Example 1-1, thereby synthesizing bis- (2,2-dinitropropyl) acetal by a batch method. went.

(Comparative Example 1-2)
A 10 mL test tube was charged with (A) 8.5 mmol of 2,2-dinitropropanol, (B) 6.8 mmol of paraaldehyde (as acetaldehyde equivalent) and 0.50 g of Nafion SAC13 manufactured by Aldrich, and stirred using a magnetic stirrer. The child was rotated at about 300 rpm and reacted at a reaction temperature of 20 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, Nafion SAC13 was filtered, and extraction, washing, and drying post-treatment were performed under the same conditions as in Example 1-1 to synthesize bis- (2,2-dinitropropyl) acetal by a batch method. It was.

(Comparative Example 1-3)
A 10 mL test tube was charged with (A) 8.5 mmol of 2,2-dinitropropanol, (B) 6.8 mmol of paraaldehyde (as acetaldehyde equivalent), and 0.50 g of Nafion NR50 manufactured by Aldrich, and stirred using a magnetic stirrer. The child was rotated at about 300 rpm and reacted at a reaction temperature of 20 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, Nafion NR50 is filtered, and post-treatment of extraction, washing, and drying is performed under the same conditions as in Example 1-1 to synthesize bis- (2,2-dinitropropyl) acetal by a batch method. It was.

(Comparative Example 1-4)
(D _AB ) Continuous bis- (2,2-dinitropropyl) acetal under the same conditions and procedure as in Example 1-1 except that the mixing ratio (B) / (A) of the mixed solution was 0.2. Synthesis by the method was performed.

(Comparative Example 1-5)
(D _AB ) Continuous bis- (2,2-dinitropropyl) acetal under the same conditions and procedure as in Example 1-1 except that the mixing ratio (B) / (A) of the mixed solution was 1.5. Synthesis by the method was performed.

The results of Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-5 are summarized in Table 1. In addition, (B) / (A) is a mixing ratio (molar ratio) of (A) 2,2-dinitropropanol and (B) paraaldehyde (where (B) is a value converted to acetaldehyde).

(Example 2-1)
Tank 1 was charged with 18 mL of a mixture of (A) 2,2-dinitropropanol, (B) paraaldehyde and methylene chloride ((A) 34 mmol, (B) acetaldehyde conversion value 27 mmol, methylene chloride up to 18 mL), A bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that 20 mL of methylene chloride and 5 mL of distilled water were charged in the recovery unit 6.

(Example 2-2)
The tank 1 was charged with 18 mL of a mixed liquid of (A) 2,2-dinitropropanol, (B) paraaldehyde, and MTBE ((A) 34 mmol, (B) acetaldehyde-converted value 27 mmol, up to 18 mL with MTBE). Then, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1.

(Example 2-3)
A tank 1 was charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde and ethyl acetate (34 mmol of (A), (B) acetaldehyde conversion value 27 mmol, and made up to 18 mL with ethyl acetate), A bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that 20 mL of ethyl acetate and 5 mL of distilled water were charged into the recovery unit 6.

(Comparative Example 2-1)
A tank 1 was charged with 18 mL of a mixture of (A) 2,2-dinitropropanol, (B) paraaldehyde and acetone ((A) 34 mmol, (B) acetaldehyde conversion value 27 mmol, up to 18 mL with acetone), and the recovery unit A synthesis of bis- (2,2-dinitropropyl) acetal by a continuous method was performed under the same conditions and procedures as in Example 1-1 except that the extraction and washing steps in 6 were omitted.

(Comparative Example 2-2)
A tank 1 was charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde and acetonitrile ((A) 34 mmol, (B) acetaldehyde-converted value 27 mmol, up to 18 mL with acetonitrile), and the recovery unit A synthesis of bis- (2,2-dinitropropyl) acetal by a continuous method was performed under the same conditions and procedures as in Example 1-1 except that the extraction and washing steps in 6 were omitted.

(Comparative Example 2-3)
Tank 1 is charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde, and tetrahydrofuran (THF) ((A) 34 mmol, (B) acetaldehyde converted value 27 mmol, THF up to 18 mL). The bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1 except that the extraction and washing steps in the recovery unit 6 were omitted.

Table 2 summarizes the results of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3. In addition, (B) / (A) is a mixing ratio (molar ratio) of (A) 2,2-dinitropropanol and (B) paraaldehyde (where (B) is a value converted to acetaldehyde).

(Example 3-1)
The same conditions and procedure as in Example 1-1, except that an adsorbent column 7 (ID 10 mm × L 98 mm) packed with 12 g of molecular sieve 13X (packing rate 65%) was placed between the reactor 3 and the recovery unit 6. Then, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner.

(Example 3-2)
Tank 1 was charged with 18 mL of a mixture of (A) 2,2-dinitropropanol, (B) paraaldehyde and methylene chloride ((A) 34 mmol, (B) acetaldehyde conversion value 27 mmol, methylene chloride up to 18 mL), The recovery unit 6 was charged with 20 mL of methylene chloride and 5 mL of distilled water, and an adsorbent column 7 (ID 10 mm × L 98 mm) packed with molecular sieve 13X 12 g (packing rate 65%) was placed between the reactor 3 and the recovery unit 6. Except for the above, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1.

(Example 3-3)
A tank 1 was charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde and MTBE ((A) 34 mmol, (B) acetaldehyde conversion value 27 mmol, MTBE up to 18 mL), and reactor 3 and the recovery unit 6 were arranged under the same conditions and procedure as in Example 1-1, except that an adsorbent column 7 (ID 10 mm × L 98 mm) packed with 12 g of molecular sieve 13X (packing rate 65%) was placed. Synthesis of-(2,2-dinitropropyl) acetal was performed in a continuous manner.

(Example 3-4)
A tank 1 was charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde and ethyl acetate (34 mmol of (A), (B) acetaldehyde conversion value 27 mmol, and made up to 18 mL with ethyl acetate), The recovery unit 6 was charged with 20 mL of ethyl acetate and 5 mL of distilled water, and an adsorbent column 7 (ID 10 mm × L 98 mm) packed with molecular sieve 13X 12 g (packing rate 65%) was placed between the reactor 3 and the recovery unit 6. Except for the above, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner under the same conditions and procedures as in Example 1-1.

(Example 3-5)
The same conditions and procedure as in Example 1-1, except that an adsorbent column 7 (ID 10 mm × L 98 mm) packed with 12 g of molecular sieve 5A (packing rate 65%) was placed between the reactor 3 and the recovery unit 6. Then, bis- (2,2-dinitropropyl) acetal was synthesized in a continuous manner.

(Example 3-6)
A tank 1 was charged with 18 mL of a mixed solution of (A) 2,2-dinitropropanol, (B) paraaldehyde and MTBE ((A) 34 mmol, (B) acetaldehyde conversion value 27 mmol, MTBE up to 18 mL), and reactor Adsorbent column 7 (ID 10 mm × L 98 mm) packed with 12 g (packing rate 56%) of silica gel A type (relative humidity 90% (JISZ0701-1977): 30.0 or more) between 3 and the recovery unit 6 Was synthesized in the continuous manner of bis- (2,2-dinitropropyl) acetal under the same conditions and procedures as in Example 1-1.

The results of Examples 3-1 to 3-6 are summarized in Table 3. In addition, (B) / (A) is a mixing ratio (molar ratio) of (A) 2,2-dinitropropanol and (B) paraaldehyde (where (B) is a value converted to acetaldehyde).

  In Examples 1-1 to 1-8, the recovery rate of BDNPA was high and the GC purity was also high. On the other hand, Comparative Examples 1-1 to 1-3 had a low recovery rate because they were synthesized in a batch mode. Further, in Comparative Example 1-4, since the mixing ratio (B) / (A) was low, the recovery rate was low as compared with Examples 1-1 to 1-8. In Comparative Example 1-5, since the mixing ratio (B) / (A) was high, the recovery rate was low as compared with Examples 1-1 to 1-8. Examples 2-1 to 2-3 using a nonpolar solvent as a reaction solvent had a higher recovery rate than Comparative Examples 2-1 to 2-3 using a polar solvent. In Examples 3-1, 3-2 and 3-5, in which the reaction solution obtained in the reactor 3 was passed through the adsorbent column 7 packed with synthetic zeolite, high GC purity was achieved. Examples 3-3 and 3 In the case of -4, the GC purity could be improved as compared with the case where the adsorbent column 7 was not passed. On the other hand, in Example 3-6 using silica gel as the adsorbent, the GC purity was not improved.

1 Tank 2 Pump 3 Reactors 4 and 5 Piping 6 Recovery unit 7 Adsorbent column

Claims (7)

In the flow path of the flow reactor, bis- (2,2) in which (A) a mixture of 2,2-dinitropropanol and (B) acetaldehyde source is continuously reacted in the presence of (C) acid. -Dinitropropyl) acetal production method comprising:
The (C) acid is a solid acid disposed in the flow path,
The reaction temperature in the flow channel is 0 to 50 ° C.,
The mixing ratio (molar ratio) of the component (A) and the component (B) (however, the component (B) is converted to acetaldehyde) is (B) / (A) = 0.5 to 1.0,
A method for producing bis- (2,2-dinitropropyl) acetal, which does not use a polar solvent as a reaction solvent.   The method for producing bis- (2,2-dinitropropyl) acetal according to claim 1, wherein the solid acid is a cationic ion exchange resin.   The method for producing bis- (2,2-dinitropropyl) acetal according to claim 1, wherein the solid acid is a solid superacid.   The method for producing bis- (2,2-dinitropropyl) acetal according to claim 3, wherein the solid superacid is a copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether].   The method for producing bis- (2,2-dinitropropyl) acetal according to any one of claims 1 to 4, wherein the reaction solvent is a nonpolar solvent.   The method for producing bis- (2,2-dinitropropyl) acetal according to claim 5, wherein the nonpolar solvent is methylene chloride. A reaction liquid obtained by the method for producing bis- (2,2-dinitropropyl) acetal according to any one of claims 1 to 6 is passed through a column packed with synthetic zeolite, and the reaction liquid is separated from the reaction liquid. A method for purifying bis- (2,2-dinitropropyl) acetal in which by-products are continuously removed.

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