2,5-Dihydroxybenzaldehyde is an organic compound with the molecular formula C7H6O3 and CAS 1194-98-5. It is a light yellow crystalline form, usually present in powder or crystal form, with a special aldehyde taste, similar to the odor of bitter almonds. During the melting process, it will gradually turn yellow and sublimate at high temperatures. It can be soluble in water, but its solubility is not high. It is also slightly soluble in organic solvents such as alcohols and ethers. This compound consists of a benzene ring, an aldehyde group, and a hydroxyl group. Among them, the aldehyde group is located at the adjacent position of the benzene ring, and both hydroxyl groups are located at the intermediate position of the benzene ring. It is a reducing compound that can react with alkali to generate corresponding phenolic salts. It can undergo benzoin condensation reaction with acetaldehyde under acidic conditions, producing benzoic acid. In addition, it can also undergo nucleophilic addition reactions with ammonia or amine compounds. There are various uses in the preparation of benzoin, including as an aldehyde source, protectant, condensation agent, impurity removal, catalyst, solvent, pre-treatment raw material, modification of structure, and synthesis of analogues. These uses make the product an indispensable and important compound in the process of preparing benzoin.
2,5-Dihydroxybenzaldehyde is an important organic compound with specific molecular structures.
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Molecular configuration: The configuration of 2,5-Dihydroxybenzaldehyde molecules is a planar structure. This is due to the six carbon atoms and two hydroxyl oxygen atoms on its benzene ring being coplanar. This planar structure gives molecules greater stability in space.
Bond angle and bond length: In 2,5-Dihydroxybenzaldehyde molecules, the bond length of carbon carbon single bonds is about 1.54 angstroms, the bond length of carbon hydrogen bonds is about 1.09 angstroms, and the bond length of oxygen hydrogen bonds is about 0.97 angstroms. These bond lengths are within the expected range, reflecting normal covalent bond properties.
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Hydrogen bonding and intramolecular interactions: 2,5-Dihydroxybenzaldehyde molecules have two hydroxyl groups that can act as hydrogen bond donors or acceptors. Specifically, hydrogen bonds can be formed between the hydrogen atoms of hydroxyl groups and adjacent carbonyl oxygen atoms within the molecule, enhancing the stability of the molecule. In addition, there are other intramolecular interactions, such as van der Waals forces and π - π interactions.
Electron cloud distribution and charge distribution: Through calculation and experimental methods, the electron cloud distribution and charge distribution of 2,5-Dihydroxybenzaldehyde molecules can be obtained. These data reflect the electron density and charge density of molecules in different regions, which helps to understand the electronic properties and chemical reactivity of molecules.
Infrared and Raman spectroscopy analysis: Through infrared and Raman spectroscopy techniques, the absorption and scattering information of 2,5-Dihydroxybenzaldehyde molecules during vibration can be obtained. These pieces of information are closely related to the structure and chemical bond properties of molecules, and can be used to identify the vibrational mode of molecules, determine the type and strength of chemical bonds, and so on.
X-ray crystallographic analysis: X-ray crystallography is a method of directly obtaining molecular structure information. By collecting X-ray diffraction data, the precise three-dimensional structure of 2,5-Dihydroxybenzaldehyde molecules can be analyzed. This method can provide information such as distance, angle, and dihedral angle between atoms in molecules, which is of great significance for understanding the configuration, conformation, and chemical reactivity of molecules.
Nuclear magnetic resonance (NMR) spectroscopy analysis: NMR spectroscopy is a commonly used method for analyzing molecular structures. By collecting NMR signals from different nuclear species (such as hydrogen, carbon, nitrogen, etc.), the distribution information, chemical environment, and interconnection mode of different types of atoms in the molecule can be obtained. For 2,5-Dihydroxybenzaldehyde molecules, their structure can be further verified through hydrogen spectroscopy, carbon spectroscopy, and other related techniques for measurement and analysis.
2,5-Dihydroxybenzaldehyde has multiple uses in the preparation of benzoin.
1. Research purpose: In the study of the synthesis and properties of benzoin, 2,5-Dihydroxybenzaldehyde is also an important experimental reagent. By using it and other experimental reagents, it is convenient to conduct synthesis experiments and mechanism studies.
2. Aldehyde protecting agent: In the process of synthesizing benzoin, 2,5-Dihydroxybenzaldehyde can also be used as a protective agent for aldehyde groups. Due to the fact that aldehyde groups are active functional groups that are easily oxidized or react with other compounds, the use of 2,5-Dihydroxybenzaldehyde can protect the aldehyde groups and improve the efficiency and yield of synthesis.
3. Condensing agent: 2,5-Dihydroxybenzaldehyde can be used as a condensing agent in the synthesis of benzoin. In a condensation reaction, it can react with another compound to generate a new compound, such as Knoevenagel condensation with benzaldehyde to produce benzoic acid.
4. Removing impurities: In the process of synthesizing benzoin, there are often some impurities, such as unreacted raw materials and by-products. The use of 2,5-Dihydroxybenzaldehyde can conveniently remove these impurities and improve the purity and quality of the product.
5. Catalyst: 2,5-Dihydroxybenzaldehyde can be used as a catalyst for the synthesis of benzoin. By using catalysts, the reaction rate can be accelerated, and the yield and quality of products can be improved.
6. Solvent: 2,5-Dihydroxybenzaldehyde can be used as a solvent in the synthesis of benzoin. It can dissolve some insoluble raw materials or products, improving the efficiency of the reaction.
7. Pre treated raw materials: Before synthesizing benzoin, 2,5-Dihydroxybenzaldehyde can be used to pre treat the raw materials. For example, it can react with raw materials to generate intermediates such as semi acetals or acetals, facilitating subsequent synthesis steps.
8. Structure modification: By using 2,5-Dihydroxybenzaldehyde as a modifier, specific modifications can be made to the structure of benzoin. For example, other functional groups can be introduced or the position of substituents can be changed.
9. Synthetic analogues: 2,5-Dihydroxybenzaldehyde can be conveniently used to synthesize some compounds similar to benzoin. These compounds have similar properties and uses to benzoin, but may have slightly different structures.
The detailed steps for preparing 2,5-Dihydroxybenzaldehyde through the condensation reaction of phenol and acrolein are as follows:
1. Add phenol and acrolein to a round bottom flask, then add an appropriate amount of sodium hydroxide solution, stir and slowly heat the reaction solution to reflux state. At this time, phenol and acrolein undergo condensation reaction under alkaline conditions to produce 2,5-dihydroxyphenylacrolein.
2. After the reaction is completed, cool the reaction solution to room temperature, and then add an appropriate amount of concentrated hydrochloric acid to make the pH value of the solution acidic.
3. Wash the upper organic layer with sodium carbonate solution in a separating funnel to remove unreacted phenol and acrolein, and then perform column chromatography to separate and purify the product 2,5-Dihydroxybenzaldehyde.
Chemical equation:
C6H5OH + CH2=CHCHO → C6H5(OH)CH=CHCHO
C6H5(OH)CH=CHCHO + HCl → C6H5(OH)CH=CHCOOH + HCl
C6H5(OH)CH=CHCOOH → C6H5(OH)CHO + H2O
In the above synthesis method, the first step is to generate 2,5-dihydroxyphenylacrolein through the condensation reaction of phenol and acrolein under alkaline conditions; The second step is to add concentrated hydrochloric acid to undergo an acidolysis reaction of the generated 2,5-dihydroxybenzaldehyde to produce 2,5-Dihydroxybenzaldehyde and water.