3,4-Dihydroxybenzaldehyde
[CAS# 139-85-5]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic acid
• Name: 3,4-Dihydroxybenzaldehyde
• Synonyms: Protocatechualdehyde
• Molecular Formula: C₇H₆O₃
• Molecular Weight: 138.12
• CAS Registry Number: 139-85-5
• EC Number: 205-377-7
• SMILES: C1=CC(=C(C=C1C=O)O)O

Properties

• Density: 1.4±0.1 g/cm³, Calc.^*
• Melting point: 152-157 °C (Expl.)
• Index of Refraction: 1.674, Calc.^*
• Boiling Point: 295.4±20.0 °C (760 mmHg), Calc.^*
• Flash Point: 146.7±18.3 °C, Calc.^*
• Water solubility: 50 g/L (20 °C) (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

3,4-Dihydroxybenzaldehyde, also known as protocatechualdehyde, is a naturally occurring aromatic compound featuring a benzene ring with two hydroxyl groups at the 3- and 4-positions and an aldehyde group at the 1-position. This catechol derivative is widely recognized for its roles in biological pathways and its applications in chemical synthesis, pharmaceuticals, and material science.

The discovery of 3,4-dihydroxybenzaldehyde can be traced to early studies on plant phenolics. It was identified as a secondary metabolite in various plants, where it contributes to defense mechanisms and serves as a precursor to other bioactive molecules. Its natural abundance and ease of isolation have made it a subject of significant interest in natural product chemistry.

In synthetic organic chemistry, 3,4-dihydroxybenzaldehyde serves as a versatile intermediate. Its hydroxyl groups and aldehyde functionality make it amenable to a wide range of chemical transformations, such as condensation reactions, oxidation, and coupling processes. It is frequently used in the synthesis of flavor compounds, fragrances, and dyes. Its reactivity has also been harnessed to develop advanced functional materials, including polymeric systems and metal-organic frameworks.

One of the most prominent applications of 3,4-dihydroxybenzaldehyde is in the pharmaceutical industry. It acts as a building block for synthesizing a variety of bioactive molecules, including antioxidants, anti-inflammatory agents, and antitumor compounds. Research has demonstrated its potential in inhibiting oxidative stress and mitigating inflammatory responses, making it a candidate for developing therapeutic agents.

The compound is also used in the production of synthetic catechins and other flavonoids, mimicking structures found in natural antioxidants. These derivatives have shown promising applications in nutraceuticals and functional foods, offering health benefits such as cardiovascular protection and improved metabolic health.

In analytical chemistry, 3,4-dihydroxybenzaldehyde is employed as a reagent for detecting and quantifying amines and other nucleophiles. Its reactivity with such compounds forms colored products, facilitating their identification and analysis. This utility underscores its significance in both research and industrial applications.

The stability of 3,4-dihydroxybenzaldehyde under various conditions requires careful handling, particularly to prevent oxidation of its catechol moiety. Proper storage and the use of stabilizing agents ensure its longevity and effectiveness for intended applications.

3,4-Dihydroxybenzaldehyde continues to be an essential compound across multiple scientific domains. Its diverse reactivity, natural origin, and applicability in creating functional molecules highlight its enduring importance in both fundamental research and applied sciences.

References

2008. Apoptotic cell death through inhibition of protein kinase CKII activity by 3,4-dihydroxybenzaldehyde purified from Xanthium strumarium. Natural Product Research.
DOI: 10.1080/14786410802076333

2024. Flavonoid, Fatty Acid, and Phenolic Constituents from the Whole Plants of Smilax sieboldii. Chemistry of Natural Compounds.
DOI: 10.1007/s10600-024-04475-4

2017. Simultaneous determination and pharmacokinetics of danshensu, protocatechuic aldehyde, 4-hydroxy-3-methyloxyphenyl lactic acid and protocatechuic acid in human plasma by LC-MS/MS after oral administration of Compound Danshen Dripping Pills. Journal of Pharmaceutical and Biomedical Analysis.
DOI: 10.1016/j.jpba.2017.06.014