Technical method for preparing 2-ethyl-2-hexenal by catalyzing self-condensation of n-butyraldehyde with acidic ionic liquid

The technology of an acidic ionic liquid and a process method, applied in the field of green chemistry, can solve the problems that the liquid alkali catalyst cannot be reused, the stability of the solid alkali catalyst is poor, and the cost of treating the three wastes is high, achieves good industrial application prospects, and overcomes the cumbersome post-processing process. , the effect of high thermal stability and chemical stability

Active Publication Date: 2012-10-03
HEBEI UNIV OF TECH
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  • Abstract
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Problems solved by technology

[0008] The purpose of the present invention is to provide a method for the self-condensation of n-butyraldehyde to prepare 2-butyraldehyde in view of the shortcomings of the current technology that the liquid alkal

Method used

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  • Technical method for preparing 2-ethyl-2-hexenal by catalyzing self-condensation of n-butyraldehyde with acidic ionic liquid
  • Technical method for preparing 2-ethyl-2-hexenal by catalyzing self-condensation of n-butyraldehyde with acidic ionic liquid
  • Technical method for preparing 2-ethyl-2-hexenal by catalyzing self-condensation of n-butyraldehyde with acidic ionic liquid

Examples

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preparation example Construction

[0041] other The preparation method of acidic ionic liquid is the same.

[0042] The Lewis acidic ionic liquid involved in the present invention is characterized by chloroaluminate acidic ionic liquid, prepared by the method described by Wikes et al. (Inorg.Chem., 1982, 21:1263). With [Bmim]Cl-AlCl 3 For example:

[0043] (1) Add the purified N-methylimidazole and chlorobutane into a three-necked flask at a molar ratio of 1:1-1:1.5, and react for 24-48 hours at a reaction temperature of 60-80°C , washed and dried to obtain light yellow viscous [Bmim]Cl.

[0044] (2) Under nitrogen protection, [Bmim]Cl was added to the three-necked upper bottle, and AlCl 3 The molar ratio of [Bmim]Cl to [Bmim]Cl is 1:1-3:1 and slowly add anhydrous AlCl in batches 3 , stir evenly, and react at 60-80°C until brown transparent [Bmim]Cl-AlCl is obtained 3 .

[0045] The preparation method of other Lewis acidic ionic liquids is the same.

Embodiment 1

[0047] In a 100ml autoclave, put 40g of n-butyraldehyde, and then add [Bmim]Cl-ZnCl with 1% n-butyraldehyde weight 2 ionic liquid, with N 2 Air replacement, magnetic stirring, and reaction at 150°C for 5 hours. After the reaction, the reaction solution was left to stand. After the reaction solution was separated, the upper layer liquid was taken for gas chromatography analysis. The conversion rate of n-butyraldehyde was 72.7%. The selectivity of -2-hexenal is 59.5%.

[0048] Examples 2-80 were carried out according to the operation steps of Example 1, and the reaction conditions and results are shown in the summary table.

[0049]

[0050]

[0051]

[0052]

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Abstract

The invention relates to a technical method for preparing 2-ethyl-2-hexenal by catalyzing self-condensation of n-butyraldehyde with an acidic ionic liquid. The technical method comprises the following steps: adding the n-butyraldehyde and an acidic ionic liquid catalyst into a high-pressure autoclave, wherein the using amount of the acidic ionic liquid catalyst is 1-50 percent of the mass of the n-butyraldehyde; and magnetically stirring at 50-150 DEG C and reacting for 0.5-12h, wherein after self-condensation reaction of the n-butyraldehyde, the 2-ethyl-2-hexenal is obtained and the acidic ionic liquid catalyst is a Bronsted acidic ionic liquid or a Lewis acidic ionic liquid. The Bronsted acidic ionic liquid catalyst and the Lewis acidic ionic liquid catalyst are high in catalytic activity, good in selectivity, mild in reaction conditions and reusable; the conversion rate of the n-butyraldehyde is as high as 94.5%; the highest selectivity of the 2-ethyl-2-hexenal is 99.3%; and the acidic ionic liquid catalyst has higher catalytic performance than the traditional industrial liquid alkali catalyst and has a good prospect for industrial application.

Description

technical field [0001] The invention relates to the technical field of green chemistry, in particular to a process for preparing 2-ethyl-2-hexenal by catalyzing the self-condensation of n-butyraldehyde with an acidic ionic liquid. Background technique [0002] The self-condensation of n-butyraldehyde to prepare 2-ethyl-2-hexenal (that is, octenal) is a typical aldol condensation reaction, which can be carried out under the condition of acid or base catalyst. Due to the strong electronegativity of the oxygen atom, the carbonyl group has an electron-withdrawing inductive effect; in addition, the carbon-hydrogen bond on the α-carbon of the carbonyl group has a σ-π hyperconjugation effect with the carbonyl group. The combined effect of inductive effect and hyperconjugation effect makes the hydrogen on the α-carbon atom active, and the active α-hydrogen can move between the α-carbon and carbonyl oxygen. Therefore, carbonyl compounds exist in a pair of tautomers, ie, keto and eno...

Claims

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Application Information

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IPC IPC(8): C07C47/21C07C45/74
Inventor 赵新强陈翠娜安华良王延吉
Owner HEBEI UNIV OF TECH
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