JP2022079247A - Method for producing secondary alcohol - Google Patents

Abstract

To provide a method for producing secondary alcohol with good production efficiency by providing a continuous type rising method with good reactivity, specifically, good production efficiency.SOLUTION: A method for producing secondary alcohol includes: a) supplying a metaboric acid, saturated aliphatic hydrocarbon and reaction gas containing a molecular oxygen into a reactor, liquid-phase oxidizing the saturated aliphatic hydrocarbon with the reaction gas containing the molecular oxygen in the presence of the metaboric acid, and obtaining a reaction liquid containing an oxide; b) esterifying the oxide, and obtaining a reaction liquid containing a borate compound; c) distilling the reaction liquid containing the borate compound, separating the distilled reaction liquid into unreacted saturated aliphatic hydrocarbon and a distillation residue; d) hydrolyzing the distillation residue and separating the hydrolyzed distillation residue into orthoboric acid and an organic layer; e) saponifying the organic layer, and separating the saponified alkali into an alkali aqueous solution layer and a crude alcohol layer; and f) purifying the crude alcohol layer and obtaining secondary alcohol, in which the reactor is composed of two or more reactors capable of being switched to a batch type and a continuous type, the saturated aliphatic hydrocarbon is added to each reactor of the two or more reactors, the metaboric acid is added to the most upstream reactor of the two or more reactors, the most upstream reactor on starts to obtain the oxide in the batch type, and the reactor is switched to the continuous type when an oxygen concentration difference in an inlet and an outlet of the most upstream reactor becomes 0.5 vol.% or more by monitoring the oxygen concentration difference.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a secondary alcohol.

Secondary alcohols are useful as raw materials for synthetic detergents, surfactants, plasticizers and the like. Secondary alcohols undergo an oxidation reaction step in which a reaction gas containing molecular oxygen is introduced into a saturated aliphatic hydrocarbon in the presence of metaboric acid to obtain a borate compound, and then a hydrolysis step and saponification. A technique that can be obtained through a process is known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 56-131531

Patent Document 1 discloses a technique for performing an oxidation reaction step in a batch manner, but it is desirable to carry out a continuous oxidation reaction step in order to increase the production amount.

However, in the conventional technique, it has been found that even if an attempt is made to connect a plurality of reactors into a continuous system, the reactivity is poor and the production is reduced.

Therefore, it is an object of the present invention to provide a method for producing a secondary alcohol having good production efficiency by providing a method for setting up a continuous system having good reactivity, that is, good production efficiency.

In one embodiment for solving the above problems, a) a reaction gas containing metaboric acid, saturated aliphatic hydrocarbon and molecular oxygen is supplied to the reactor, and saturated aliphatic carbonization is performed in the presence of metaboric acid. Hydrogen is liquid-phase oxidized with a reaction gas containing molecular oxygen to obtain a reaction solution containing an oxide, b) the oxide is esterified to obtain a reaction solution containing a borate compound, and c) the borate compound. The reaction solution containing the above is distilled to separate it into unreacted saturated aliphatic hydrocarbon and distillation residue, d) the distillation residue is hydrolyzed to separate it into orthoboric acid and an organic layer, and e) the organic. A method for producing a secondary alcohol, which comprises saponifying the layer with an alkali to separate it into an alkaline aqueous solution layer and a crude alcohol layer, and f) purifying the crude alcohol layer to obtain a secondary alcohol. The reactor comprises two or more reactors that can be switched between batch and continuous, and comprises adding saturated aliphatic hydrocarbons to each of the two or more reactors, the two or more. It has the addition of metaboric acid to the most upstream reactor of the reactor and begins to batch obtain the oxide in the most upstream reactor at the inlet of the most upstream reactor. It is a method for producing a secondary alcohol, which comprises monitoring the difference in oxygen concentration at the outlet and switching to a continuous formula when the difference in oxygen concentration becomes 0.5% by volume or more.

According to the present invention, it is possible to provide a method for producing a secondary alcohol having good production efficiency by providing a method for setting up a continuous system having good reactivity, that is, good production efficiency.

FIG. 1 shows a schematic diagram in step (a). FIG. 2 is a schematic diagram of the reactor used in Example 1.

Hereinafter, the present invention will be described. The present invention is not limited to the following embodiments. Unless otherwise specified, the operation and the measurement of physical properties are measured under the condition of room temperature (20 to 25 ° C.).

In one embodiment of the present invention, a) a reaction gas containing metaboric acid, saturated aliphatic hydrocarbon and molecular oxygen is supplied to the reactor, and the saturated aliphatic hydrocarbon is molecularly formed in the presence of metaboric acid. Liquid phase oxidation is performed with a reaction gas containing oxygen to obtain a reaction solution containing an oxide, b) the oxide is esterified to obtain a reaction solution containing a borate compound, and c) a reaction containing the borate compound. The liquid is distilled to separate it into unreacted saturated aliphatic hydrocarbons and distillation residue, d) the distillation residue is hydrolyzed to separate it into orthoboric acid and an organic layer, and e) the organic layer is alkaline. The reactor is a method for producing a secondary alcohol, which comprises saponifying and separating into an alkaline aqueous solution layer and a crude alcohol layer, and f) purifying the crude alcohol layer to obtain a secondary alcohol. , Consisting of two or more reactors switchable between batch and continuous, having the addition of saturated aliphatic hydrocarbons to each of the two or more reactors, the most of the two or more reactors. It has the addition of metaboric acid to the upstream reactor, initiates batch acquisition of the oxide in the most upstream reactor, and oxygen at the inlet and outlet of the most upstream reactor. It is a method for producing a secondary alcohol, which comprises monitoring the concentration difference and switching to a continuous formula when the oxygen concentration difference becomes 0.5% by volume or more. According to such an embodiment, it is possible to provide a method for setting up a continuous system having good reactivity, that is, good production efficiency, and by extension, to provide a method for producing a secondary alcohol having good production efficiency. can.

Hereinafter, each step will be described in detail.

(Step (a))
(Step (a): Oxidation reaction step)
In step (a), a reaction gas containing metaboric acid, saturated aliphatic hydrocarbons and molecular oxygen (also simply referred to as “oxygen” in the present specification) is supplied to the reactor in the presence of metaboric acid. , Saturated aliphatic hydrocarbons are subjected to liquid phase oxidation with a reaction gas containing molecular oxygen to obtain a reaction liquid containing an oxide.

As used herein, the "saturated aliphatic hydrocarbon" is a mixture of saturated aliphatic hydrocarbons (normal paraffin) having 8 to 30 carbon atoms, unless otherwise specified. Preferably, the saturated aliphatic hydrocarbon contains a saturated aliphatic hydrocarbon having 10 to 15 carbon atoms (n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane and n-pentadecane) as a main component. It is a mixture containing, more preferably, a mixture containing a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms (n-dodecane, n-tridecane and n-tetradecane) as a main component. Here, "containing a saturated aliphatic hydrocarbon as a main component" means that a saturated aliphatic hydrocarbon having a predetermined carbon number is contained in an amount of more than 90% by mass (preferably more than 95% by mass) with respect to the total saturated aliphatic hydrocarbon. It means that it is contained in a ratio of (upper limit: 100% by mass). The average molecular weight of the saturated aliphatic hydrocarbon is 114 or more and 422 or less, preferably 142 or more and 212 or less, and more preferably 170 or more and 198 or less. Saturated aliphatic hydrocarbons may be synthetic or commercially available. Similarly, metaboric acid may be synthetic or commercially available. An embodiment of the method of synthesis will be described in the section <Method for producing metaboric acid> described later.

In the step (a), the reactor comprises two or more reactors that can be switched between a batch type and a continuous type, and saturated aliphatic hydrocarbons may be added to each of the reactors of the two or more reactors. Then, it has to add a hydrocarbon to the most upstream reactor of the two or more reactors, and starts to obtain the oxide in a batch system in the most upstream reactor, and starts to obtain the oxide in a batch manner. When the difference in oxygen concentration between the inlet and the outlet of the reactor on the side is monitored and the difference in oxygen concentration becomes 0.5% by volume or more, the system may be switched to a continuous system.

FIG. 1 is a schematic diagram showing a reactor capable of measuring oxygen concentration. As shown in FIG. 1, the (plural) reactor 1 is composed of two reactors (11, 12). The volumes of the most upstream reactor (reactor 11 in FIG. 1) and, if necessary, one or more reactors (reactor 12 in FIG. 1) may be appropriately determined according to the production amount of the target product. The two reactors (11, 12) can be switched between a batch type and a continuous type by being connected by a pipe 2. Each reactor (11, 12) has an inlet 3 to which a saturated aliphatic hydrocarbon and metaboric acid are added, an inlet 4 to which a reaction gas containing molecular oxygen is introduced, and a reaction gas containing molecular oxygen. Is provided with an outlet 5 from which the gas is discharged.

In one embodiment of the invention, the reaction gas comprises molecular oxygen. In addition, it may contain ammonia and the like. The reaction gas, together with the circulating gas, can be introduced into each reactor (11, 12) via the inlet 4. Examples of the circulating gas include an inert gas, and for example, nitrogen gas and the like are suitable. In one embodiment of the invention, the concentration of ammonia in the reaction gas can be 10% to 1000% by volume.

In one embodiment of the present invention, in each of the reactors (11, 12), the inlet 4 and the outlet 5 are provided with measuring instruments capable of measuring the oxygen concentration (not shown). The inlet 4 and the outlet 5 each consist of gas pipes. In one embodiment of the present invention, each of the inlet 4 (gas pipe) and the outlet 5 (gas pipe) of the reactor 11 is provided with a measuring instrument capable of measuring the oxygen concentration, and the inlet 4 (gas pipe) of the reactor 12 is provided. And the outlet 5 (gas pipe) are each equipped with a measuring instrument capable of measuring one oxygen concentration, and each is equipped with a measuring instrument capable of measuring one oxygen concentration.

By providing such a measuring instrument, it is possible to monitor the oxygen concentration difference between the inlet 4 and the outlet 5. To put it plainly, the fact that the concentration of oxygen entering from the inlet 4 is low at the outlet 5 means that the oxidation reaction is proceeding. In one embodiment of the invention, oxygen concentrations at the inlet and outlet of the most upstream reactor (reactor 11 in FIG. 1) and optionally one or more other reactors (reactor 12 in FIG. 1). When the difference is monitored and the oxygen concentration difference becomes 0.5% by volume or more, the system is switched to the continuous system. In one embodiment of the present invention, the difference in oxygen concentration at the inlet and outlet of each of the two or more reactors is monitored, and when the difference in oxygen concentration becomes 0.5% by volume or more, the system is switched to a continuous system. .. Here, if the difference in oxygen concentration is less than 0.5% by volume, the reactivity of the oxidation reaction in a continuous formula is deteriorated, and it is not possible to provide a method for producing a secondary alcohol having good production efficiency. In the present specification, the oxygen concentration difference can be calculated by (oxygen concentration at the inlet (% by volume))-(oxygen concentration at the outlet (% by volume)).

The difference in oxygen concentration at the inlet and outlet of the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) in one embodiment of the present invention is different, respectively. Independently, 0.5% by volume or more (preferably 1.0% by volume or more). The difference in oxygen concentration at the inlet and outlet of the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) in one embodiment of the present invention is different, respectively. Independently, it is 10% by volume or less (preferably 5.0% by volume or less). By such an embodiment, the oxidation reaction can be stably carried out.

In one embodiment of the invention, saturated aliphatic hydrocarbons are added to each reactor (reactors 11 and 12 in FIG. 1) via the inlet 3.

In one embodiment of the present invention, metaboric acid is added to the reactor on the most upstream side of the reactor (reactor 11 in FIG. 1). In one embodiment of the present invention, metaboric acid is less than 10% by mass, 7% by mass or less, 5% by mass or less, based on the saturated aliphatic hydrocarbon contained in the reactor (reactor 11 in FIG. 1) on the most upstream side of the reactor. Add at a concentration of 7% by mass or less, or 3% by mass or less. If metaboric acid is added to the reactor at a concentration of 10% by mass or more, the difference in oxygen concentration between the inlet and the outlet of at least the most upstream reactor may not be 0.5% by volume or more. In one embodiment of the present invention, metaboric acid is, for example, 0.1% by mass or more with respect to the saturated aliphatic hydrocarbon contained in the reactor on the most upstream side of the reactor (reactor 11 in FIG. 1). Add in concentration, but not limited to this.

In one embodiment of the invention, metaboric acid is added not only to the most upstream reactor (reactor 11 in FIG. 1) but more preferably to one or more other reactors (reactor 12 in FIG. 1). Have that. In this way, by adding metaboric acid to each reactor (reactors 11 and 12 in FIG. 1) separately, the amount of splashes caused by metaboric acid is suppressed, the blockage of pipes is significantly suppressed, and the production efficiency is improved. Has an effect.

In one embodiment of the present invention, metaboric acid is independently added to each saturated aliphatic hydrocarbon contained in one or more other reactors (reactor 12 in FIG. 1) in an amount of less than 10% by mass and 7% by mass, respectively. % Or less, 5% by mass or less, or 3% by mass or less. According to such an embodiment, the desired effect of the present invention can be efficiently achieved. In one embodiment of the invention, metaboric acid is independently added to each saturated aliphatic hydrocarbon contained in one or more other reactors (reactor 12 in FIG. 1), for example, by 0.1 mass. It is added at a concentration of% or more, but is not limited to this.

In one embodiment of the present invention, the internal temperatures of the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) are independently set to 140. The temperature is set to more than 200 ° C., 150 to 190 ° C., or 160 to 180 ° C. If the temperature is 140 ° C. or lower, there is a possibility that the oxygen concentration difference at least at the inlet and outlet of the most upstream reactor cannot be 0.5% by volume or more. Further, the oxidation reaction can be stably carried out by setting the temperature below 140 ° C. and 200 ° C. or lower. Here, "internal temperature" means a value measured by a thermometer installed so as to come into contact with the contents contained in the reactor.

In one embodiment of the present invention, the temperatures of the reaction gases introduced into the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) are independent of each other. The temperature is set to more than 140 ° C. and 200 ° C. or lower, 150 to 190 ° C., or 160 to 180 ° C. According to such an embodiment, the oxygen concentration difference can be efficiently set to 0.5% by volume or more. Further, the oxidation reaction can be stably carried out by setting the temperature below 140 ° C. and 200 ° C. or lower. Here, the temperature of the reaction gas means a value measured by a thermometer installed so as to come into contact with the reaction gas. The air volume of the reaction gas is independently 100 to 1000 liters / hour, preferably 350 to 600 liters / hour, etc. per 1000 g of saturated aliphatic hydrocarbons.

In this preferred embodiment, the circulating gas is introduced into the most upstream reactor (reactor 41 in FIG. 3) and one or more other reactors (reactor 42 in FIG. 3). The preferable temperature range of the circulating gas is the same as the preferable temperature range of the reaction gas.

In one embodiment of the present invention, the reaction gas is introduced and stopped in the most upstream reactor (reactor 11 in FIG. 1) and, if necessary, one or more other reactors (reactor 12 in FIG. 1). Carry out intermittent supply that repeats. At this time, the intermittent supply is carried out while monitoring. That is, the monitoring is carried out by intermittent supply in which the introduction and the introduction stop of the reaction gas are repeated. Explaining a specific operation method, for example, the reaction gas is applied to the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) for an arbitrary time. Introduce. After that, the introduction of the reaction gas is stopped for an arbitrary time. The reaction gas is supplied in a plurality of cycles, with the introduction of the reaction gas once and the introduction stop once as one cycle. The number of cycles is not particularly limited, and the monitoring may be performed until the oxygen concentration difference becomes 0.5% by volume or more, but as a guide, for example, about 1 to 10 times or 2 to 7 times. , Or about 3 to 6 times, but is not limited to this.

In one embodiment of the invention, the reaction gas introduced into the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) upon introduction. The oxygen concentration in the above is 0.5% by volume (vol%) or more and 10% by volume (vol%) or less, preferably 0.5% by volume (vol%) or more and 2.5% by volume (vol%). The following, etc.)

In one embodiment of the present invention, upon introduction, the concentration of molecular oxygen in the reaction gas is monotonically increased. Further, in one embodiment of the present invention, when the introduction is made, the slope calculated by the least squares method in the change in the concentration of molecular oxygen in the reaction gas is positive. In this way, the concentration of molecular oxygen in the reaction gas is (monotonically) increased (that is, not decreased or increased) with the passage of time in the intermittent supply, or calculated by the minimum square method in the change of concentration. By making the slope positive (that is, the concentration may decrease over time, but the concentration increases on average), it is possible to make a continuous equation with good reactivity. The production volume can be increased.

In one embodiment of the present invention, the single introduction time in the intermittent supply is set to 0.5 to 10 minutes, 0.5 to 5 minutes, or 0.5 to 3 minutes. By such an embodiment, it is possible to efficiently make a predetermined oxygen concentration difference.

In one embodiment of the present invention, one introduction stop time in the intermittent supply is set to 0.5 to 10 minutes and 1 to 10 minutes.

In one embodiment of the present invention, the intermittent supply of the reaction gas is switched to the continuous supply after the predetermined oxygen concentration difference is reached. In one embodiment of the present invention, the reaction gas is continuously supplied from the inlet 4 of the reactor 11 of the reactors 11 and 12 in FIG.

In one embodiment of the present invention, after switching to the continuous equation, a saturated aliphatic hydrocarbon is further supplied. In one embodiment of the present invention, after switching to the continuous equation, saturated aliphatic hydrocarbons are sequentially supplied. In one embodiment of the present invention, after switching the intermittent supply of the reaction gas to continuous supply, saturated aliphatic hydrocarbons are sequentially supplied from the inlet 3 of the reactor 11.

In one embodiment of the invention, the most upstream reactor (reactor 11 in FIG. 1) and one or more other reactors (reactor 12 in FIG. 1) are communicated with each other. In this way, a continuous type (continuous flow type) is started from the batch type to obtain a reaction solution (oxidation reaction product) containing an oxide. Here, the saturated aliphatic hydrocarbon supplied after switching to the continuous type may be the same as or different from the saturated aliphatic hydrocarbon added to the reactors (11, 12) above. Good, but preferably the same.

In one embodiment of the present invention, the oxidation reaction step may be carried out under atmospheric pressure (normal pressure), under pressure or under reduced pressure, but is usually carried out under atmospheric pressure (normal pressure) to 30 kg / cm ² G. .. Further, the liquid phase oxidation reaction may be carried out with stirring (the reactor may be equipped with a stirrer).

In one embodiment of the present invention, one or more reactors may be, for example, a stirring tank type or a bubble column type.

<Manufacturing method of metaboric acid>
One embodiment of the invention is i) dehydrate orthoboric acid in the presence of saturated aliphatic hydrocarbons in a dehydrator to give a mixture containing metaboric acid, saturated aliphatic hydrocarbons and water (step (i)); ii. ) After distilling off a part of the saturated aliphatic hydrocarbon and water from the mixture, the saturated aliphatic hydrocarbon and water are separated (step (ii)); iii) the saturated aliphatic separated in the above ii). In the i), the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 2% by mass, that is, the hydrocarbon is returned to the i) (step (iii)). It is a manufacturing method (first aspect).

As a method for producing a secondary alcohol, a) a saturated aliphatic hydrocarbon is liquid-phase oxidized with a molecular oxygen-containing gas in the presence of metaboric acid to obtain a reaction solution containing an oxide (step (a-). 1)), the oxide is esterified to obtain a reaction solution containing a borate compound (step (a-2)) (the steps (a-1) and (a-2) are collectively referred to as "step (a-2)". ) ”, B) The reaction solution containing the borate compound is distilled to separate it into unreacted saturated aliphatic hydrocarbon and distillation residue (step (b)), and c) the distillation residue is hydrated. It is decomposed and separated into an aqueous layer containing orthoboric acid and an organic layer (step (c)), and d) the organic layer is subjected to a hydrocarbon treatment with an alkali and separated into an alkaline aqueous solution layer and a crude alcohol layer (step (step (step)). d)), e) Purification of the crude alcohol layer (step (e)) is performed. In the above method, unreacted saturated hydrocarbons can be recovered from several steps (for example, step b above), and it is useful in the process to reuse the unreacted saturated hydrocarbons in the reaction system (for example, step b above). For example, Japanese Patent Application Laid-Open No. 56-131531). Therefore, when orthoboric acid is dehydrated with a dehydrator in the presence of saturated aliphatic hydrocarbons to produce metaboric acid, the unreacted saturated aliphatics recovered in the process of producing the secondary alcohol as described above. Attempts were made to reuse hydrocarbons (recovered saturated aliphatic hydrocarbons), but if only the recovered unreacted saturated aliphatic hydrocarbons were used as they were in the reaction, deposits would be formed on the inner walls and pipes, resulting in production. It was not possible to stably produce hydrocarbons due to reduced efficiency and equipment troubles. The present inventors have diligently studied stable metaboric acid production processes by various methods. As a result, the alcohol contained in the unreacted saturated aliphatic hydrocarbon (recovered saturated aliphatic hydrocarbon) recovered in the secondary alcohol production process (for example, after the oxidation reaction) causes the borate compound as a deposit. I guessed it was to generate. Therefore, as a result of diligent studies on the alcohol content in the saturated aliphatic carbon used for the production of metaboric acid, the alcohol content in the saturated aliphatic hydrocarbon used for the dehydration reaction of orthoboric acid was 2% by mass. It was found that the formation of borate compounds, which cause deposits, can be suppressed or prevented by controlling the content to less than%. According to the above method, since deposits do not adhere to the reactor and the inner wall of the pipe during the dehydration reaction, it is possible to effectively prevent an increase in stirring power and blockage of the pipe. Therefore, according to the above method, metaboric acid can be stably produced. On the other hand, when the unreacted hydrocarbon recovered by the method described in Patent Document 1 is circulated in the dehydration reaction, deposits are attached to the inner wall of the reactor and the pipe, and the stirring power is increased and the pipe is piped. May cause obstruction. This is because the recovered unreacted saturated aliphatic hydrocarbon contains an alcohol in which at least one hydrogen atom of the saturated aliphatic hydrocarbon is substituted with a hydroxyl group in a proportion of 2% by mass or more, so that this alcohol is used in the dehydration step. It is presumed that it reacts with orthoboric acid to form a borate compound, which causes deposits. It should be noted that the mechanism for exerting the above-mentioned effects and effects according to the configuration of the present invention is an estimation, and the present invention is not limited to the above estimation.

Hereinafter, each step of the first aspect will be described.

(Step (i))
In this step, a dehydrator is charged with a saturated aliphatic hydrocarbon (in the present specification, the saturated aliphatic hydrocarbon is also simply referred to as “hydrocarbon”) and orthoboric acid to prepare a slurry to prepare a saturated aliphatic hydrocarbon. Dehydrate orthoboric acid in the presence of hydrogen. This produces metaboric acid, resulting in a mixture (slurry) containing metaboric acid, saturated aliphatic hydrocarbons and water and, in some cases, unreacted orthoboric acid.

In this step, the content of the alcohol component in the saturated aliphatic hydrocarbon (raw material saturated aliphatic hydrocarbon) charged is less than 2% by mass. When the content of the alcohol component in the raw material saturated aliphatic hydrocarbon is 2% by mass or more, a borate compound is generated during the dehydration reaction of orthoboric acid, which induces the formation of deposits on the inner wall of the reactor and the inner wall of the pipe. However, metaboric acid cannot be produced stably. From the viewpoint of producing more stable metaboric acid, the content of the alcohol component in the saturated aliphatic hydrocarbon is preferably 1.5% by mass or less, particularly preferably less than 1% by mass (lower limit: 0% by mass or detection limit). Below). That is, in a preferred embodiment of the present invention, in i), the content of the alcohol component in the saturated aliphatic hydrocarbon is 1.5% by mass or less. In a more preferable embodiment of the present invention, in i), the content of the alcohol component in the saturated aliphatic hydrocarbon is less than 1% by mass. In the present specification, the content of the alcohol component in the saturated aliphatic hydrocarbon adopts the value measured by gas chromatography. The above-mentioned "alcohol component" refers to an alcohol (mixture) in which a hydrogen atom of a saturated aliphatic hydrocarbon having 6 to 30 carbon atoms is substituted with a hydroxyl group. The "alcohol component" is preferably a mixture containing an alcohol as a main component, in which a hydrogen atom of a saturated aliphatic hydrocarbon having 8 to 20 carbon atoms is substituted with a hydroxyl group, and more preferably a saturated fat having 10 to 15 carbon atoms. A mixture containing an alcohol in which a hydrogen atom of a group hydrocarbon is substituted with a hydroxyl group as a main component, particularly preferably a mixture containing an alcohol in which a hydrogen atom of a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms is substituted with a hydroxyl group as a main component. Intended.

Here, the saturated aliphatic hydrocarbon is a mixture of saturated aliphatic hydrocarbons (normal paraffin) having 8 to 30 carbon atoms. Preferably, the saturated aliphatic hydrocarbon contains a saturated aliphatic hydrocarbon having 10 to 15 carbon atoms (n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane and n-pentadecane) as a main component. A mixture containing, more preferably, a saturated aliphatic hydrocarbon having 12 to 14 carbon atoms (n-dodecane, n-tridecane and n-tetradecane) as a main component. Here, "containing a saturated aliphatic hydrocarbon as a main component" means that a saturated aliphatic hydrocarbon having a predetermined carbon number is contained in an amount of more than 90% by mass (preferably more than 95% by mass) with respect to the total saturated aliphatic hydrocarbon. It means that it is contained in a ratio of (upper limit: 100% by mass). The average molecular weight of the saturated aliphatic hydrocarbon is 114 or more and 422 or less, preferably 142 or more and 212 or less, and more preferably 170 or more and 198 or less. Saturated aliphatic hydrocarbons may be synthetic or commercially available. Similarly, orthoboric acid may be synthetic or commercially available.

In the present disclosure, the mixing ratio of the saturated aliphatic hydrocarbon and orthoboric acid is not particularly limited, and the same mixing ratio as before can be applied. Specifically, the mixing ratio of saturated aliphatic hydrocarbons and orthoboric acid (saturated aliphatic hydrocarbons: mixed mass ratio of orthoboric acid) is 0.5 to 5: 1, preferably more than 1: 1. It is less than 3: 1. The amount of orthoboric acid added is, but is not limited to, 15 to 90% by mass, preferably more than 25% by mass and less than 45% by mass in the mixture (slurry).

In the present disclosure, the dehydration conditions for orthoboric acid in the presence of saturated aliphatic hydrocarbons are not particularly limited, and the same conditions as before can be applied in the same manner. For example, the dehydration temperature is 100 ° C. or higher and lower than 200 ° C., preferably 130 ° C. or higher and 180 ° C. or lower. The dehydration time is the time at which substantially all orthoboric acid is converted to metaboric acid, and other conditions (for example, the amount of orthoboric acid charged, the mixing ratio of saturated aliphatic hydrocarbons and orthoboric acid, the dehydration temperature, etc.) ) Can be selected as appropriate. The dehydration time is, for example, 3 to 7 hours, preferably 4 to 6 hours. If the dehydration time is within the above range, the dehydration can be appropriately advanced and metaboric acid can be efficiently produced. Alternatively, the amount of metaboric acid produced in the reactor is periodically measured to determine whether substantially all orthoboric acid has been converted to metaboric acid, and the dehydration reaction occurs when the desired amount of metaboric acid is produced. May be terminated. Here, "substantially all orthoboric acid is converted to metaboric acid" means more than 0.9 mol (preferably more than 0.95 mol) per 1 mol of orthoboric acid charged (upper limit: 1). It means that metaboric acid (molar) is converted. The amount of metaboric acid in the mixture can be measured by known methods. In the present specification, the amount of metaboric acid adopts the value measured by X-ray crystal structure analysis.

The dehydration reaction may be carried out under atmospheric pressure, pressurization or reduced pressure, but is usually carried out under atmospheric pressure. Further, the dehydration reaction may be carried out with stirring (the reactor may be equipped with a stirrer). Here, the stirring speed when the dehydration reaction is carried out while stirring is not particularly limited, but is, for example, 20 to 100 rpm, preferably 30 to 60 rpm. At such a stirring speed, the raw materials (saturated aliphatic hydrocarbon and orthoboric acid) can be uniformly mixed (the dehydration reaction can be uniformly carried out).

The dehydrator (reactor for carrying out the dehydration reaction) may be made of any material. Specific examples thereof include iron, copper, stainless steel (SUS), nickel alloys (for example, Hastelloy), Inconel, titanium, and titania. Of these, stainless steel (SUS), nickel alloy (for example, Hastelloy) and titania are preferable, and stainless steel (SUS) and nickel alloy (for example, Hastelloy) are more preferable. As described in detail below, orthoboric acid separated after the hydrolysis step in the production of secondary alcohols can be reused in this step. In this case, orthoboric acid contains an organic substance (organic acid such as fatty acid, fatty acid ester, fatty acid sodium, fatty acid potassium, organic acid salt, organic acid ester, etc.), but this organic substance evaporates during the dehydration reaction, and the dehydrator May cause corrosion. Therefore, it is preferable that at least the gas phase portion of the reactor is formed of a nickel alloy, particularly hastelloy having excellent heat resistance, pressure resistance and corrosion resistance. That is, in the preferred embodiment of the present disclosure, at least the gas phase portion of the dehydrator is formed of nickel alloy. In a more preferred embodiment of the present disclosure, at least the gas phase portion of the dehydrator is formed of Hastelloy. Also, in the preferred embodiment of the present disclosure, the entire dehydrator is made of nickel alloy (more preferably Hastelloy). Here, as Hastelloy, Hastelloy C-22 (composition: Ni 57.0% by mass, Cr 20.5% by mass, Mo 14.2% by mass, Fe 2.3% by mass, W: 3.2% by mass, V 0.25% by mass, C 0.01% by mass), Hastelloy C-276 (composition: Ni 57.0% by mass, Cr 15.5% by mass, Mo 16.0% by mass, Fe 6.0% by mass, W: 4.0% by mass, V 0.3% by mass, C 0.01% by mass) and the like. Also, the "gas phase portion of the dehydrator" is intended to be the portion of the dehydrator that is in contact with at least one vapor of saturated aliphatic hydrocarbons, orthoboric acid, water and metaboric acid. Specifically, the gas phase portion of the dehydrator is preferably in the range from the top of the dehydrator to 60% with respect to the total height of the dehydrator (more preferably 30% or more and 60% or less, in particular. It is preferably a portion up to 40% or more and 50% or less). That is, in a preferred embodiment of the present invention, the range from the top of the dehydrator to 60% (more preferably 30% or more and 60% or less, particularly preferably 40% or more and 50) with respect to the total height of the dehydrator. % Or less range) is formed of nickel alloy. Further, the present invention is a reactor for producing metaboric acid, in a range of up to 60% (preferably in a range of 30% or more and 60% or less) from the top of the reactor to the total height of the reactor. It also provides a reactor in which more preferably 40% or more and 50% or less) is formed of a nickel alloy. Further, "the dehydrator is formed of the material A" includes a form in which the dehydrator is formed of the material A and a form in which the inner surface of the dehydrator formed of the material B is covered with the material A. .. That is, for example, "at least the gas phase portion of the dehydrator is formed of a nickel alloy" is a form in which the entire dehydrator is formed of a nickel alloy; the gas of a dehydrator made of another material (for example, stainless steel). A form in which the inner wall of the phase portion is coated with a nickel alloy by spraying or lining, etc .; A form in which the entire inner wall of a dehydrator made of another material (for example, stainless steel) is coated with a nickel alloy by spraying or lining, etc. is included. do.

In this step, orthoboric acid is intramolecularly dehydrated in the presence of saturated aliphatic hydrocarbons and converted to metaboric acid by the following reaction. Metaboric acid has α-type and β-type depending on its crystal structure, but β-type metaboric acid is preferable from the viewpoint of thermal stability (clocking prevention effect) and the like. Such β-type metaboric acid can be produced by the method described in Japanese Patent Publication No. 48-37242 and the preferable dehydration conditions as described above.

(Step (ii))
In this step, the saturated aliphatic hydrocarbon and water are distilled off from the dehydration reaction product obtained in the above step (i), and then the saturated aliphatic hydrocarbon and water are separated.

During the dehydration step of the above step (i), the saturated aliphatic hydrocarbon and water evaporate (a mixed vapor of the vapor of the saturated aliphatic hydrocarbon and water vapor is generated). These mixed vapors are withdrawn from the dehydration reactor and separated. Here, the method for separating the saturated aliphatic hydrocarbon and water in the mixed vapor is not particularly limited. For example, these vapors are extracted from the upper part of the dehydrator to the outside of the system, the vapors extracted from the system are condensed into a liquid, and the condensed product is condensed into an aqueous layer (water) and an organic layer (saturated) in a settler (separation tank). There is a method of separating into aliphatic hydrocarbons). Of the water layer (water) and the organic layer (saturated aliphatic hydrocarbon) separated in this way, water is extracted from the system.

(Step (iii))
In this step, the saturated aliphatic hydrocarbon separated in the step (ii) is returned to the step (i).

Most of the saturated aliphatic hydrocarbons separated in this step contain alcohol components (alcohol components in which at least one hydrogen atom of the saturated aliphatic hydrocarbon is replaced with a hydroxyl group) that produces a borate compound that causes deposits. Not included or not included at all. Therefore, even if the saturated aliphatic hydrocarbon evaporated during the dehydration reaction of orthoboric acid is used for the dehydration reaction of orthoboric acid, the alcohol component reacts with orthoboric acid to form a borate compound with little or no. Therefore, it is possible to effectively prevent the formation of deposits on the inner wall of the reactor and the pipe, and therefore the increase in the stirring power and the blockage of the pipe. Therefore, according to the method of the present disclosure, metaboric acid can be stably produced. Further, since it is not necessary to add fresh hydrocarbon separately, it is preferable from the viewpoint of production cost and the like. Here, the content of the alcohol component in the saturated aliphatic hydrocarbon separated in the above step (ii) is preferably less than 2% by mass, more preferably in the saturated aliphatic hydrocarbon separated in the above step (ii). It is preferably 1.5% by mass or less, particularly preferably less than 1% by mass (lower limit: 0% by mass or detection limit or less).

(Step (b): Esterification step)
In the step (b), the oxide (oxidation reaction product) is esterified to obtain a reaction solution containing a borate compound. In step (b), a borate compound is produced, but there are other unreacted aliphatic hydrocarbons, free alcohols and metaboric acid. Free alcohol has a boiling point close to that of unreacted saturated aliphatic hydrocarbons, so it is difficult to separate the two. Therefore, in the esterification step (b), this alcohol is orthoboric acid esterified and converted into a borate compound.

That is, in the step (b), the free alcohol contained in the oxidation reaction product obtained in the step (a) is esterified (orthoboric acid esterification) to obtain a borate compound. In this step, the free alcohol present in the oxidation reaction product obtained in step (a) is reacted with metaboric acid to convert it into a borate compound, but usually, excess metaboric acid is present in the oxidation reaction product. Therefore, it is not necessary to add new metaboric acid here, but there are cases where new metaboric acid is added.

The method of conversion to the borate compound is not particularly limited, but it is preferable to apply a reduced pressure treatment to the reaction solution (oxidation reaction product) containing the oxide obtained in the step (a). By doing so, the free alcohol and the excessively added metaboric acid (or newly added metaboric acid) can be esterified to obtain a borate compound. The conditions for this esterification are not particularly limited. In one embodiment of the present invention, the pressure in step (b) is, for example, 50 to 200 hPa or 90 to 170 hPa. In one embodiment of the present invention, the temperature in step (b) is, for example, 100 to 220 ° C. or 160 to 180 ° C. In one embodiment of the present invention, the processing time in step (b) is, for example, 5 to 80 minutes or 20 to 60 minutes. The orthoboric acid esterification treatment may be carried out in a nitrogen stream. Under such treatment conditions, the alcohol contained in the oxidation reaction product can be more efficiently esterified with orthoboric acid (a borate compound can be produced in a higher yield).

In addition, in the above-mentioned steps (a) to (b), the occurrence of the following reaction is included.

(Step (c): Recovery step of unreacted saturated aliphatic hydrocarbon)
In the step (c), the reaction solution containing the borate compound obtained in the above step (b) is distilled into unreacted saturated aliphatic hydrocarbon (distillate) and distillation residue (column bottom residue). Separate and recover unreacted saturated aliphatic hydrocarbons (unreacted saturated aliphatic hydrocarbon recovery step). Since the distillate and the residual liquid at the bottom of the column have a large boiling point difference, they can be easily separated by distillation.

In this step, as a method for distilling the borate compound, known methods such as simple distillation (for example, flash distillation) and molecular distillation can be used, but the method is not particularly limited thereto. The distillation pressure is, for example, under reduced pressure of 1 to 50 hPa, preferably 3 to 25 hPa, but is not limited thereto. The distillation temperature (particularly the column bottom temperature) is 130 to 250 ° C., preferably 150 to 205 ° C., and is not limited thereto. The distillation time is, but is not limited to, 1 to 205 minutes, preferably 25 to 120 minutes, and the like.

The unreacted saturated aliphatic hydrocarbon recovered in this step may be reused (circulated) in the above-mentioned oxidation reaction step (a). In this case, for example, even if the saturated aliphatic hydrocarbon of the distillate is removed and then reused as it is in the above oxidation reaction step (a); the carbonyl compound contained in the saturated aliphatic hydrocarbon recovered in this step. And even if the olefins are hydrogenated and then reused in the oxidation reaction step (a); or, for example, as described in JP-A-56-131531, the saturated aliphatic charcoal recovered in this step. Hydrogen is separated into, for example, an organic layer containing a fatty acid and a fatty acid ester and an aqueous layer by contacting with an alkaline aqueous solution, and if necessary, the organic layer is washed with hot water (alkali treatment step) and contained in the organic layer. After hydrogenating the unreacted saturated aliphatic hydrocarbon (hydrogen treatment step), the alcohol component contained in the unreacted saturated aliphatic hydrocarbon was orthoborate esterified (esteration step), and then in the oxidation reaction step (a). It may be reused, but is not limited to the above. The saturated aliphatic hydrocarbon recovered in the recovery step contains 2% by mass or more (for example, about 2 to 5% by mass) of an alcohol component.

(Step (d): Hydrolysis step)
In this step, the distillation residue separated in the above step (c) is hydrolyzed to separate an aqueous layer containing orthoboric acid and an organic layer.

Specifically, hot water is added to the distillation residue and hydrolyzed to separate the aqueous layer containing orthoboric acid and the organic layer. Here, the temperature (liquid temperature) of the hot water is, but is not limited to, 70 to 150 ° C., preferably 90 to 100 ° C. and the like. The amount of hot water added is, but is not limited to, 1 to 20 times by mass, preferably 2 to 10 times by mass, or the like with respect to the distillation residue. The hydrolysis time is, but is not limited to, 5 to 60 minutes, preferably 20 to 30 minutes, and the like. Under such conditions, the distillation residue can be sufficiently hydrolyzed to more efficiently separate the aqueous layer containing orthoboric acid from the organic layer.

(Step (e): Saponification step)
In this step, the organic layer separated in the above step (d) is saponified with an alkali to separate it into an alkaline aqueous solution layer and a crude alcohol layer (saponification step). This makes it possible to remove organic acids and organic acid esters.

Here, as the alkali, for example, sodium hydroxide, potassium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate and the like can be used, but the alkali is not limited thereto. Further, if necessary after the saponification treatment with the above alkali, it may be washed with water. The saponification condition is not particularly limited, and the same conditions as before can be applied in the same manner. For example, the saponification temperature is 120 to 160 ° C, preferably 135 to 145 ° C and the like, but is not limited thereto. The saponification time is, but is not limited to, 30 to 120 minutes, preferably 50 to 90 minutes, and the like. Under such conditions, the saponification process can proceed more efficiently.

(Step (f): Alcohol refining step)
In this step, the crude alcohol layer separated in the above step (e) is purified. As a result, the desired secondary alcohol is obtained.

Here, the purification method is not particularly limited, and a known method can be applied in the same manner or appropriately modified. For example, it can be purified by distilling or fractionating the crude alcohol layer. The purification pressure at this time is, but is not limited to, 1 to 45 hPa, preferably 4 to 12 hPa and the like. Under such conditions, it can be appropriately separated depending on the boiling point range (for example, a fraction having a boiling point range of 95 ° C. or higher and lower than 120 ° C. and a fraction having a boiling point range of 120 to 150 ° C.). In the above case, the fraction having a boiling point range of 95 ° C. or higher and lower than 120 ° C. usually contains a small amount of saturated aliphatic hydrocarbon, carbonyl compound and monohydric primary alcohol (monoalcohol). Further, the fraction having a boiling point range of 120 to 150 ° C. contains a trace amount of a carbonyl compound and a secondary alcohol (monoalcohol), and in this case, most of the secondary alcohol is a desired monohydric secondary alcohol. be.

It should be noted that at least one selected from the heavy separation step, the alkali treatment step (particularly the potassium hydroxide treatment step) and the light separation step according to a conventionally known method between the above step (e) and this step (f). The process may be performed.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples, and the technical means disclosed in each Example will be used. Examples obtained in appropriate combinations are also included in the scope of the present invention.

(Example 1)
<(A): Oxidation step>
As shown in FIG. 1, a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (with an average molecular weight of 184 and 12 carbon atoms) in each of the reactors (11, 12) of the two reactors 1 connected in series. 1000 g and 1000 g of saturated aliphatic hydrocarbons (n-dodecane, n-tridecane and n-tetradecane) to be contained in a proportion of more than 95% by mass based on the total mass of the mixture (hereinafter, also referred to as NP), respectively. I stuck. Next, metaboric acid was charged into each reactor (11, 12) so as to be 1% by mass and 1% by mass, respectively, with respect to NP.

The internal temperatures of each reactor (11, 12) were all raised to 170 ° C. Then, a circulating gas (nitrogen gas: 170 ° C.) was introduced into each reactor (11, 12) via the inlet 4.

Then, intermittent supply of the reaction gas was repeatedly introduced and stopped for each reactor (11, 12).

More specifically, the temperature of the reaction gas introduced into each reactor (11, 12) was adjusted to 170 ° C. Further, the oxygen concentration of the reaction gas introduced into each reactor (11, 12) at this time was adjusted to be 0.5 to 10% by volume and 0.5 to 10% by volume, respectively. At this time, the time for introducing the reaction gas into each reactor (11, 12) at one time was set to 1 to 3 minutes. In addition, the time for stopping the introduction of the reaction gas once was also set to 1 to 3 minutes. The introduction was carried out so that the slope calculated by the least squares method in the change in the concentration of molecular oxygen in the reaction gas became positive.

Then, the intermittent supply was carried out while monitoring the oxygen concentration difference at the inlet 4 and the outlet 5 of each reactor (11, 12). It was confirmed that the predetermined oxygen concentration difference became 1.0% by volume (that is, 0.5% by volume or more) 1.0 hour after the reaction gas was first introduced into each reactor (11, 12). ..

After the above confirmation, the intermittent supply of the reaction gas is switched to the continuous supply, the NP is sequentially supplied at 50 mL / min from the inlet 3 of the reactor 11, and the reactors (11, 12) are communicated with each other in a continuous manner. An oxidation reaction step was carried out in (continuous flow system) to obtain an oxide (oxidation reaction mixed solution).

<Steps (b) to (f)>
After the oxidation reaction, the reaction solution containing the oxide (oxidation reaction product) was depressurized to esterify with alcohol and boric acid added in excess to obtain a borate compound. This esterification was carried out at 105 hPa, 165 ° C., 60 minutes (esterification step). Next, the unreacted saturated aliphatic hydrocarbon was removed by distilling the borate compound (borate ester mixture) at 200 ° C. and 7 hPa (unreacted saturated aliphatic hydrocarbon recovery step). Then, the residual liquid was hydrolyzed with a large amount (2% by mass with respect to the residual liquid) of hot water at 95 ° C. for 20 minutes, and separated into an aqueous layer containing orthoboric acid and an organic layer (hydrolysis step). The obtained organic layer was saponified and washed with water at 140 ° C. for 70 minutes using sodium hydroxide to remove organic acids and organic acid esters (sakenization step). This organic layer was fractionated at 7 hPa to obtain a distillate having a boiling point range of 95 ° C. or higher and lower than 120 ° C. as the first distillate and a distillate having a boiling point range of 120 to 150 ° C. as the second distillate. Here, the first fraction (boiling point range 95 to 120 ° C. fraction) was a mixture of a small amount of a saturated aliphatic hydrocarbon, a carbonyl compound and a monohydric primary alcohol (monoalcohol). The secondary fraction (boiling point range 120-150 ° C. fraction) is a mixture of trace amounts of carbonyl compounds and secondary alcohols (monoalcohols), where most of the secondary alcohols are monohydric secondary. It was alcohol.

Since the production amount of the secondary alcohol in one day was 4 kg by starting up by the continuous method (continuous distribution method) by this method, it was judged that the reactivity of the oxidation step was good.

In this embodiment, the experiment was conducted in "series", but it has been confirmed that the same result can be obtained by making it "parallel".

(Example 2)
The same method as in Example 1 was carried out except that the reaction gas was a mixture of air and ammonia instead of air. At this time, the concentration of ammonia in the reaction gas introduced into each reactor (11, 12) was adjusted to be 10 volume ppm to 1000 volume ppm, 10 volume ppm to 1000 volume ppm, respectively.

Since the production amount of the secondary alcohol in one day was 4 kg by starting up by the continuous method (continuous distribution method) by this method, it was judged that the reactivity of the oxidation step was good.

(Comparative Example 1)
In Example 1, the internal temperatures of each reactor (11, 12) were all changed to 140 ° C. As a result, the difference in oxygen concentration was 0.1% by volume (that is, less than 0.5% by volume). By launching the system in a continuous system (continuous distribution system) by this method, the amount of secondary alcohol produced per day was 0.7 kg, so it was judged that the reactivity of the oxidation process was poor.

(Comparative Example 2)
In Example 1, metaboric acid was charged into each reactor (11, 12) so as to be 11% by mass and 11% by mass, respectively, with respect to NP. As a result, the difference in oxygen concentration was 0.1% by volume, which was less than 0.5% by volume. By launching the system in a continuous system (continuous distribution system) by this method, the amount of secondary alcohol produced per day was 0.7 kg, so it was judged that the reactivity of the oxidation process was poor.

(Comparative Example 3)
In Example 1, intermittent supply was performed for 0.5 hours after the reaction gas was first introduced into each reactor (11, 12). As a result, the difference in oxygen concentration was 0.1% by volume and less than 0.5% by volume. By starting up in a continuous system (continuous distribution system) by this method, the amount of secondary alcohol produced per day was 0.7 kg, so it was judged that the reactivity of the oxidation process was poor.

(Example 3)
In the reactor 1 with a stirrer 2 having a capacity of 5 L shown in FIG. 2, 1700 g of a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight: 184, indicated as “NP” in FIG. 2) and orthoboric acid. 1000 g was charged to prepare an orthoboric acid mixture M. The mixture of saturated aliphatic hydrocarbons as a raw material contains saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (n-dodecane, n-tridecane and n-tetradecane) and saturated aliphatic hydrocarbons having 12 to 14 carbon atoms. It is contained in a ratio of more than 95% by mass based on the total mass of the mixture of. Moreover, when the content of the alcohol component in the mixture of saturated aliphatic hydrocarbons was measured by gas chromatography, it was below the detection limit (substantially no alcohol component was contained). As the reactor 1, the entire reactor is made of stainless steel (SUS316), and the inner wall of the reactor upper part 3 (hatched portion in FIG. 2; height of Hastelloy-coated portion / total height of reactor = 45%) is Hastelloy C-22 ( Composition: Ni 57.0% by mass, Cr 20.5% by mass, Mo 14.2% by mass, Fe 2.3% by mass, W: 3.2% by mass, V 0.25% by mass, C 0.01% by mass %) And a 0.5 mm thick lining was used (up to 45% of the total height of the dehydrator from the top of the dehydrator is covered with Hastelloy).

The obtained orthoboric acid mixture M is heated to 160 ° C. by steam while stirring with a stirrer 2 at a rate of 45 rpm, and the orthoboric acid is intramolecularly dehydrated in the presence of a saturated aliphatic hydrocarbon mixture for 5 hours. It was converted to β-type metaboric acid. As a result, 2330 g of a mixture containing 630 g of β-type metaboric acid and 1700 g of saturated aliphatic hydrocarbon was obtained (yield of β-type metaboric acid: 1 mol with respect to 1 mol of orthoboric acid) (step (i)). It was confirmed by X-ray crystal structure analysis that it was β-type metaboric acid. Further, steam and vapors of saturated aliphatic hydrocarbons (“water + NP” in FIG. 2) are generated during the dehydration reaction, and these vapors are extracted from the upper part of the reactor through the pipe 4 to the condenser. Introduced into 5 to condense steam, water condensed in a condenser and saturated aliphatic hydrocarbons were introduced into a separation tank (Settler) 6 to separate water from saturated aliphatic hydrocarbons (NP) (NP). Step (ii)), water was taken out of the system, and the saturated aliphatic hydrocarbon (NP) was returned to the reactor 1 through the pipe 7 to carry out the above dehydration reaction. The content of the alcohol component in the saturated aliphatic hydrocarbon (NP) after separation in the separation tank (Settler) 6 was measured by gas chromatography and found to be below the detection limit (substantially the alcohol component). Did not include).

After the above reaction was completed, the inner wall of the reactor and the inside of the pipe were visually observed. As a result, almost no deposits were found on the inner wall of the reactor or inside the piping. No corrosion was observed on the inner wall of the reactor (particularly the inner wall of the upper part of the reactor).

As shown in FIG. 2, a mixture of saturated aliphatic hydrocarbons having 12 to 14 carbon atoms (average molecular weight of 184 and 12 carbon atoms) in each of the reactors (11, 12) of the two reactors 1 connected in series. 973 g and 973 g of saturated aliphatic hydrocarbons (n-dodecane, n-tridecane and n-tetradecane) to be contained in a proportion of more than 95% by mass based on the total mass of the mixture (hereinafter, also referred to as NP), respectively. I stuck. Next, 37 g and 37 g of the previously synthesized mixture of β-type metaboric acid and NP (so that the metaboric acid is 1% by mass and 1% by mass with respect to NP, respectively) are applied to each reactor (11, 12). A secondary alcohol was produced by the same method as in Example 1 except that it was crowded. Since the production amount of the secondary alcohol in one day was 4 kg by starting up by the continuous method (continuous distribution method) by this method, it was judged that the reactivity of the oxidation step was good. In this embodiment, the experiment was conducted in "series", but it has been confirmed that the same result can be obtained by making it "parallel".

1 (multiple) reactors,
11 (one) reactor,
12 (one) reactor,
2 plumbing,
3 Inlet for saturated aliphatic hydrocarbons and metaboric acid,
4 Inlet for reaction gas and circulating gas,
5 Reaction gas, outlet for circulating gas,
10 reactor,
20 stirrer,
30 ... Upper part of the reactor,
40, 70 plumbing,
50 condenser,
60 Separation tank (Settler),
M Orthoboric acid mixture.

Claims (12)

a) A reaction gas containing metaboric acid, saturated aliphatic hydrocarbon and molecular oxygen is supplied to the reactor, and in the presence of metaboric acid, saturated aliphatic hydrocarbon is liquid with a reaction gas containing molecular oxygen. Phase oxidation to obtain a reaction solution containing an oxide,
b) The oxide is esterified to obtain a reaction solution containing a borate compound.
c) The reaction solution containing the borate compound is distilled to separate it into unreacted saturated aliphatic hydrocarbon and distillation residue.
d) The distillation residue is hydrolyzed to separate it into orthoboric acid and an organic layer.
e) The organic layer is alkalized to separate it into an alkaline aqueous solution layer and a crude alcohol layer.
f) A method for producing a secondary alcohol, which comprises purifying the crude alcohol layer to obtain a secondary alcohol.
The reactor consists of two or more reactors that can be switched between batch and continuous reactors.
It has the addition of saturated aliphatic hydrocarbons to each of the two or more reactors.
It has the addition of metaboric acid to the most upstream reactor of the two or more reactors.
The oxide is obtained in a batch manner in the most upstream reactor, and the oxygen concentration difference is monitored at the inlet and outlet of the most upstream reactor, and the oxygen concentration difference is 0.5 volume. % Or more, a method for producing a secondary alcohol, which comprises switching to a continuous system. The production method according to claim 1, wherein the metaboric acid is added to one or more reactors other than the most upstream reactor. The production method according to claim 2, wherein metaboric acid is independently added to each reactor at a concentration of less than 10% by mass with respect to each saturated aliphatic hydrocarbon contained in each reactor. The production method according to any one of claims 1 to 3, further comprising supplying a saturated aliphatic hydrocarbon after switching to the continuous formula. Claims 1 to 1, wherein the oxygen concentration difference at the inlet and the outlet of each of the two or more reactors is monitored, and when the oxygen concentration difference becomes 0.5% by volume or more, the system is switched to a continuous system. The manufacturing method according to any one of 4. The production method according to any one of claims 1 to 5, wherein the internal temperature of each reactor is independently set to 160 to 180 ° C. The production method according to any one of claims 1 to 6, wherein the temperature of the reaction gas is independently set to 160 to 180 ° C. The production method according to any one of claims 1 to 7, wherein the monitoring is carried out by intermittent supply in which the reaction gas is repeatedly introduced and stopped. The manufacturing method according to claim 8, wherein the one-time introduction time in the intermittent supply is set to 0.5 to 10 minutes. The manufacturing method according to claim 8 or 9, wherein one introduction stop time in the intermittent supply is set to 1 to 10 minutes. The production method according to any one of claims 8 to 10, wherein the concentration of molecular oxygen in the reaction gas is monotonically increased at the time of introduction. The production method according to any one of claims 8 to 10, wherein the slope calculated by the least squares method in the change in the concentration of molecular oxygen in the reaction gas is positive at the time of introduction.

Images