In order to solve the problems in the prior art, the embodiments of the present invention provide a method for producing Valeric Acid. The technical solution is as follows:
On the one hand, a method for producing Valeric Acid is provided, which is characterized in that, comprising the following steps:
(1) Preparation of Grignard reagent: a part of 1-chlorobutane is added to the mixture of metal magnesium and solvent, after heating to initiate the reaction, the remaining 1-chlorobutane is added dropwise in 3 ~ 10min, and the reaction system is maintained at reflux Under the state, after the 1-chlorobutane is dripped, the reaction system is continued to reflux until the reaction is completed, and wherein the mol ratio of 1-chlorobutane and magnesium is (1～20): 9, the 1-chlorobutane that the first part adds Alkane is (22～24)% of 1-chlorobutane total amount, and described solvent is tetrahydrofuran or ether, and the volume ratio of solvent and 1-chlorobutane is (4～5): 1;
(2) (1) gained reaction mixture is added dropwise in the reaction vessel that dry ice is housed in 10～30min, after dripping is completed, naturally rise to room temperature, add MHSO subsequently , stir, after the reaction is complete, suction filtration, and the filtrate is acidified After purification, n-valeric acid is obtained, wherein the magnesium added in (1): the dry ice added in (2): MHS0 = 9:27:7, and M is K or Na.
Preferably, in the step (1), the 1-chlorobutane added in the first part is 23% of the total amount of 1-chlorobutane.
Preferably, in the step (1), the mol ratio of 1-chlorobutane and magnesium is 1: (1.4～1.6), more preferably 2: 3.
Preferably, the step (1) is carried out under the protection of an inert gas. Since the Grignard reagent will be consumed by air and water, it will affect the reaction effect, such as nitrogen or argon.
Preferably, in the step (2), the purification refers to acidifying the filtrate to a pH value of (3~4), then extracting the acidified filtrate with ether, merging and drying the organic phases, and finally removing the ether to obtain The Valeric Acid. Usually, the reagent added during acidification is 2 mol/L dilute hydrochloric acid or 1 mol/L dilute sulfuric acid.
More preferably, the M is K.
More preferably, the solvent is tetrahydrofuran.
In the described step (1), a part of the 1-chlorobutane that was added earlier can be used as an initiator to initiate a reaction, and after the reaction is initiated, heat is released, and the reaction system is boiled, and the solvent begins to flow back. As a known technique, the initiation reaction needs to be properly heated to facilitate the initiation of the initiation reaction. Then in 3～10min (preferably 4～6min, for example 5 minutes) remaining 1-chlorobutane can be added dropwise, if the reaction is violent, the rate of addition should be properly controlled to maintain the reaction system in a reflux state. Obviously, this step temperature of reaction is relevant with the boiling point of concrete solvent, when solvent adopts tetrahydrofuran, the temperature of reaction of step (1) is controlled at 25 ℃～reflux temperature, namely before dripping remaining 1-chlorobutane, temperature of reaction is in 25 ℃～reflux temperature, after dripping remaining 1-chlorobutane, temperature of reaction is then basically stable at reflux temperature. After the remaining 1-chlorobutane is added dropwise, the required reaction time can be determined by those skilled in the art through experiments, preferably 1 ~ 3h, such as 2h.
In the described step (2), the (1) gained reaction mixture is added dropwise to the reaction vessel equipped with dry ice in 10～30min, for example the time for adding is 30 minutes.
As common knowledge in the art, the preparation of Grignard reagent needs to be carried out under anhydrous conditions, so the reaction raw materials need to ensure anhydrous, and water removal treatment can be used in advance. For example, 1-chlorobutane is frozen and deiced before being put into the reaction.