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2,5-Dimethoxybenzaldehyde: Properties, Reactivity, Synthesis and 2C-H

Contents hide
1 Abstract
2 General Information About 2,5-Dimethoxybenzaldehyde [1-4]
3 Physico-Chemical Properties of 2,5-Dimethoxybenzaldehyde [1-4]
4 Chemical Reactions [1-8]
5 Synthesis of 2,5-Dimethoxybenzaldehyde [10]
6 Conclusion
7 Bibliography

Abstract

2,5-Dimethoxybenzaldehyde is an organic compound with the chemical formula C9H10O3. It is a benzaldehyde derivative containing two methoxy groups (–OCH3) at positions 2 and 5 on the phenyl ring. This compound is a key intermediate in the synthesis of various psychoactive substances, including 2C-H and other related phenethylamines. Its physico-chemical properties, including reactivity and synthesis pathways, are of interest in the field of organic chemistry. The compound has been studied for its role as a precursor in the production of compounds with psychoactive effects, contributing to a broader understanding of its chemical characteristics and applications. This article presents a comprehensive overview of 2,5-dimethoxybenzaldehyde, including its general information, physico-chemical properties, Chemical Reactions, synthesis of 2,5-dimethoxybenzaldehyde, conclusion, and bibliography.

General Information About 2,5-Dimethoxybenzaldehyde [1-4]

IUPAC Name: 2,5-Dimethoxybenzaldehyde

CAS number is 93-02-7

Physico-Chemical Properties of 2,5-Dimethoxybenzaldehyde [1-4]

  • Molecular Formula C9H10O3
  • Molar Weight 166.17 g/mol
  • Melting Point 46-52 ℃
  • Boiling Point 146 °C / 10 mmHg (314.4384 °C / 760 mmHg) Sigma-Aldrich
  • Solubility: Solubility 795mg/l (25°C) in water; soluble in most common organic solvents
  • Color/Form: Yellow to Beige

Structural formula present on Figure 1.

Figure 1. Structure of 2,5-Dimethoxybenzaldehyde
Figure 1. Structure of 2,5-Dimethoxybenzaldehyde

Powder and crystalline solid possible of 2,5-Dimethoxybenzaldehyde the can be seen in the pictures provided in Figure 2.

Figure 2. Powder of 2,5-Dimethoxybenzaldehyde
Figure 2. Powder of 2,5-Dimethoxybenzaldehyde

Chemical Reactions [1-8]

Aromatic aldehyde hydrogenation is a pivotal chemical transformation involving the addition of hydrogen gas (H₂) to an aromatic aldehyde, leading to the reduction of the aldehyde functional group (-CHO) to a primary alcohol functional group (-CH₂OH). This intricate process entails breaking a carbon-oxygen double bond and establishing a carbon-hydrogen single bond. Aromatic aldehydes represent a class of organic compounds characterized by the presence of both an aromatic ring and an aldehyde group. The hydrogenation of these compounds is typically facilitated by a catalyst, often a metal catalyst such as palladium, platinum, or nickel, under high-pressure conditions. The reaction parameters can be fine-tuned to selectively yield the desired aromatic primary alcohol. Figure 3

Fig 3. The hydrogenation of 2,5-dimethoxybenzaldehyde

Fig 3. The hydrogenation of 2,5-dimethoxybenzaldehyde

The interplay between aromatic aldehydes and hydrogen cyanide (HCN) in the presence of bases stands as a pivotal chemical reaction of significance. In this intricate process, aromatic aldehyde engages with hydrogen cyanide, a compound harboring a cyanide ion (CN⁻) and a hydrogen ion (H⁺), under the influence of bases that function as either catalysts or facilitators for the reaction. Notably, bases like sodium hydroxide (NaOH) or potassium hydroxide (KOH) play a fundamental role by catalyzing the formation of the reactive cyanide ion, thereby amplifying the reactivity of the reaction and fostering the creation of desired products.

The essence of the reaction lies in the cyanide ion’s addition to the carbonyl carbon of the aldehyde group within the aromatic aldehyde. This addition initiates the formation of a cyanohydrin intermediate, which, depending on the specific reactants and reaction conditions, can undergo further transformations. Figure 4

Figure 4. The interaction of 2,5-dimethoxybenzaldehyde with HCN
Figure 4. The interaction of 2,5-dimethoxybenzaldehyde with HCN

The interplay between aromatic aldehydes and sodium hydrosulfite is a noteworthy chemical interaction, as depicted in Figure 5. In this process, aromatic aldehydes engage with sodium hydrosulfite. This interaction often leads to the transformation of the aldehyde functional group within the aromatic compound.

Figure 5. The interaction of 2,5-dimethoxybenzaldehyde with sodium hydrosulfite.
Figure 5. The interaction of 2,5-dimethoxybenzaldehyde with sodium hydrosulfite.

The synthesis of imines from aromatic aldehydes using ammonia or amines stands as a chemical transformation in organic synthesis, playing a crucial role in diverse applications. An imine, characterized by a carbon-nitrogen double bond (C=N), is a distinctive functional group formed during this reaction. The process involves the condensation of an aromatic aldehyde with either ammonia (NH3) or amines. During this reaction, the aldehyde group (-CHO) of the aromatic aldehyde undergoes condensation with the amino group (-NH2) of ammonia or amines. The nucleophilic amino group attacks the electrophilic carbon atom of the aldehyde, resulting in the formation of an intermediate known as a Schiff base. This Schiff base exhibits versatility, as it can further react with additional reagents to generate a variety of compounds, making it a valuable intermediate in organic synthesis. Figure 6.

Figure 6. The formation of imines from 2,5-dimethoxybenzaldehyde with ammonia
Figure 6. The formation of imines from 2,5-dimethoxybenzaldehyde with ammonia

Aromatic aldehydes interaction with oxidizing agents initiates a significant chemical transformation known as oxidation. During this process, the aldehyde group undergoes electron loss, ultimately resulting in the creation of carboxylic acids or other oxidized derivatives. Figure 7.

Figure 7. Reaction with oxidizing agents

Figure 7. Reaction with oxidizing agents

Aromatic aldehydes react with acetaldehyde at elevated temperatures. Figure 8.

Figure 8. 2,5-dimethoxybenzaldehyde react with acetaldehyde

Figure 8. 2,5-dimethoxybenzaldehyde react with acetaldehyde

The synthesis of 2,5-dimethoxyphenethylamine or 2C-H. Figure 9.

Figure 9. The synthesis of 2,5-dimethoxyphenethylamine or 2C-H from 2,5-dimethoxybenzaldehyde.
Figure 9. The synthesis of 2,5-dimethoxyphenethylamine or 2C-H from 2,5-dimethoxybenzaldehyde.

Reaction with Grignard reagent. Figure 10.

Figure 10. 2,5-dimethoxybenzaldehyde react with C2H5MgBr
Figure 10. 2,5-dimethoxybenzaldehyde react with C2H5MgBr

Reaction with PCl5. Figure 11.

Figure 11. 2,5-dimethoxybenzaldehyde react with PCl5.
Figure 11. 2,5-dimethoxybenzaldehyde react with PCl5

Reaction with HBr. Figure 12.

Figure 12. 2,5-dimethoxybenzaldehyde react with HBr.
Figure 12. 2,5-dimethoxybenzaldehyde react with HBr.

Synthesis of 2,5-Dimethoxybenzaldehyde [10]

Anethole is oxidized to anisaldehyde, which is subjected to a Baeyer­Villiger oxidation to give 4­methoxyphenol, which is subjected to a Reimer­Tiemann formylation to give 2­hydroxy­5­methoxybenzaldehyde. Methylation gives 2,5­dimethoxybenzaldehyde. Synthesis according to the scheme on Figure 13.

Figure 13. General scheme of 2,5-Dimethoxybenzaldehyde synthesis
Figure 13. General scheme of 2,5-Dimethoxybenzaldehyde synthesis

Conclusion

2,5-Dimethoxybenzaldehyde emerges as a pivotal chemical entity, showcasing its versatility as a precursor in the synthesis of psychoactive compounds like 2C-H. The compound’s distinctive reactivity and synthesis pathways not only contribute to its role in the creation of psychoactive substances but also underscore its significance in advancing of complex organic reactions.

Bibliography

  1. https://en.wikipedia.org/wiki/2C-H
  2. https://en.wikipedia.org/wiki/2,5-Dimethoxybenzaldehyde
  3. https://pubchem.ncbi.nlm.nih.gov/compound/66726
  4. https://www.chemspider.com/Chemical-Structure.60092.html
  5. Shulgin, Alexander; Shulgin, Ann (September 1991). PiHKAL: A Chemical Love Story. Berkeley, California: Transform Press. ISBN 0-9630096-0-5. OCLC 25627628. 2C-H Entry in PiHKAL
  6. https://en.wikipedia.org/wiki/Vanillin
  7. https://en.wikipedia.org/wiki/Grignard_reaction
  8. https://en.wikipedia.org/wiki/Ether
  9. Waumans, D., Bruneel, N., & Tytgat, J. (2004). Anise Oil as a Precursor for 2-Alkoxy-5-methoxybenzaldehydes. Microgram, 2, 4-10. https://www.academia.edu/6037527/Anise_Oil_as_a_Precursor_for_2_alkoxy_5_methoxybenzaldehydes
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