1. What is the reagent used in Etard reaction?
Chromyl Chloride is the reagent employed (CrO2Cl2). It's also known as Etard reagent and is a mild oxidizing agent.
2. How toluene is converted to benzoic acid?
Toluene can be transformed to benzoic acid by fully oxidizing it with a powerful oxidizing agent such as KMnO4.
3. How can toluene be converted to benzaldehyde?
Toluene can be converted to Benzaldehyde by combining it with Chromyl Chloride in a CS2 and CCl4 medium as well as then hydrolyzing intermediate product.
4. What is Etard reaction? Explain etard rection mechanism.
The partial oxidation of aromatic ring with attached methyl group to create desirable aldehydes is known as the Etard reaction.
In the Etard reaction, chromyl chloride, a mild oxidizing agent, interacts with toluene in the presence of carbon tetrachloride, a non-polar solvent. The - bonds of chromyl chloride are cleaved homolytically during this reaction. Similarly, homolytic breakage of the methyl group's C-H bonds occurs. The Etard complex, also known as the chromyl complex, is formed as a result of this reaction.
Now the etard complex is hydrolyzed, resulting in the elimination of two molecules of Cr(OH)2Cl2 and the creation of benzaldehyde. Aldehyde is formed by direct partial oxidation of the methyl group linked to the aromatic ring.
5. Mention the applications of Etard reaction.
The conversion of toluene to benzaldehyde by oxidation is particularly beneficial in the food business because benzaldehyde has an almond-like flavour. It's used to make colours, fragrances, and a variety of pharmaceutical chemicals. Aldehydes are more reactive and participate in the formation of aldols. Many chemicals, including phentermine, can be made from benzaldehyde.
6. What is the main purpose of the Etard reaction?
The main purpose of the Etard reaction is to synthesize aromatic aldehydes from alkyl-substituted aromatic compounds, particularly toluene derivatives. It provides a direct method for converting a methyl group attached to an aromatic ring into an aldehyde group.
7. What types of compounds can undergo the Etard reaction?
The Etard reaction is primarily used for alkyl-substituted aromatic compounds, especially toluene derivatives. Compounds with methyl groups attached to aromatic rings are ideal substrates for this reaction.
8. How does the presence of other functional groups affect the Etard reaction?
The presence of other functional groups can affect the Etard reaction in various ways:
9. Can the Etard reaction be used to oxidize multiple methyl groups on a single aromatic ring?
Yes, the Etard reaction can oxidize multiple methyl groups on a single aromatic ring, but the efficiency may vary. The reaction conditions and stoichiometry need to be carefully controlled to achieve selective oxidation of all methyl groups.
10. Can the Etard reaction be used to synthesize ketones?
No, the Etard reaction is specific for the synthesis of aldehydes. It cannot be used to directly synthesize ketones from alkyl-substituted aromatic compounds.
11. What is the general reaction mechanism of the Etard reaction?
The Etard reaction mechanism involves several steps:
12. What is the primary oxidizing agent used in the Etard reaction?
The primary oxidizing agent used in the Etard reaction is chromyl chloride (CrO2Cl2). This compound is responsible for oxidizing the methyl group on the aromatic ring to an aldehyde.
13. What is the role of water in the final step of the Etard reaction?
Water plays a crucial role in the final step of the Etard reaction by hydrolyzing the chromium intermediate complex. This hydrolysis step releases the aldehyde product and forms chromium-containing byproducts.
14. What is the significance of using carbon disulfide as a solvent in the Etard reaction?
Carbon disulfide (CS2) is commonly used as a solvent in the Etard reaction because it does not react with chromyl chloride and provides a suitable medium for the reaction to occur. It also helps in the formation of the chromium ester complex.
15. How does the position of the methyl group on the aromatic ring affect the Etard reaction?
The position of the methyl group on the aromatic ring can affect the reactivity and yield of the Etard reaction. Generally, methyl groups in the para- and ortho-positions react more readily than those in the meta-position due to electronic effects.
16. What is the Etard reaction?
The Etard reaction is an organic chemistry reaction that converts certain aromatic methyl groups directly into aldehydes. It involves the oxidation of alkyl-substituted aromatic compounds, typically toluene derivatives, using chromyl chloride (CrO2Cl2) as the oxidizing agent.
17. Who discovered the Etard reaction?
The Etard reaction was discovered by French chemist Alexandre Léon Etard in 1877. He first reported the oxidation of methylbenzenes using chromyl chloride to form aromatic aldehydes.
18. How does the Etard reaction compare to the Reimer-Tiemann reaction?
The Etard reaction and Reimer-Tiemann reaction are both methods for synthesizing aromatic aldehydes, but they differ in several ways:
19. What safety precautions should be taken when performing the Etard reaction?
Important safety precautions for the Etard reaction include:
20. What are some common workup procedures for the Etard reaction?
Common workup procedures for the Etard reaction include:
21. Can the Etard reaction be used to oxidize aliphatic compounds?
No, the Etard reaction is specific to aromatic compounds with alkyl substituents. It is not effective for oxidizing aliphatic compounds or non-aromatic structures.
22. What are the main advantages of the Etard reaction?
The main advantages of the Etard reaction include:
23. What are some limitations of the Etard reaction?
Some limitations of the Etard reaction include:
24. Why is chromyl chloride preferred over other oxidizing agents in the Etard reaction?
Chromyl chloride is preferred because it selectively oxidizes the methyl group to an aldehyde without further oxidation to a carboxylic acid. It also forms a stable complex with the aromatic ring, which helps direct the oxidation to the desired position.
25. How does the Etard reaction differ from other aldehyde synthesis methods?
The Etard reaction differs from other aldehyde synthesis methods in that it directly converts a methyl group on an aromatic ring to an aldehyde without the need for additional steps or protecting groups. It is specific to aromatic compounds and uses chromyl chloride as the oxidizing agent.
26. What are some common side products in the Etard reaction?
Common side products in the Etard reaction may include:
27. How does temperature affect the Etard reaction?
Temperature plays a crucial role in the Etard reaction:
28. How is the progress of the Etard reaction typically monitored?
The progress of the Etard reaction can be monitored using various analytical techniques:
29. What is the typical yield range for the Etard reaction?
The yield of the Etard reaction can vary depending on the substrate and reaction conditions. Typically, yields range from 60% to 90% for many aromatic compounds, with some substrates giving even higher yields under optimized conditions.
30. Can the Etard reaction be used in the synthesis of pharmaceutical compounds?
Yes, the Etard reaction can be used in the synthesis of pharmaceutical compounds, particularly those containing aromatic aldehyde moieties. However, its use may be limited due to concerns about chromium residues and the availability of alternative, more environmentally friendly methods.
31. What are some alternatives to the Etard reaction for synthesizing aromatic aldehydes?
Some alternatives to the Etard reaction for synthesizing aromatic aldehydes include:
32. How does the electronic nature of the aromatic ring affect the Etard reaction?
The electronic nature of the aromatic ring affects the Etard reaction in several ways:
33. Can the Etard reaction be used to synthesize heterocyclic aldehydes?
The Etard reaction is primarily used for carbocyclic aromatic compounds. Its application to heterocyclic compounds is limited and often less effective due to potential side reactions and different electronic properties of heterocycles.
34. What is the environmental impact of the Etard reaction?
The environmental impact of the Etard reaction is a concern due to:
35. How does the scale of the reaction affect the efficiency of the Etard reaction?
The scale of the reaction can affect the efficiency of the Etard reaction:
36. How does the Etard reaction compare to oxidation methods using permanganate or dichromate?
The Etard reaction differs from permanganate or dichromate oxidations in several ways:
37. Can the Etard reaction be used in conjunction with other synthetic methods?
Yes, the Etard reaction can be used in conjunction with other synthetic methods. It is often part of multi-step syntheses, where the resulting aldehyde can be further transformed using various reactions such as reductions, oxidations, condensations, or carbon-carbon bond-forming reactions.
38. What is the role of the chromium-carbon double bond in the Etard reaction mechanism?
The chromium-carbon double bond formed in the intermediate complex plays a crucial role in the Etard reaction mechanism:
39. How does the Etard reaction behave with polysubstituted aromatic compounds?
With polysubstituted aromatic compounds, the Etard reaction behavior depends on the nature and position of the substituents:
40. What are some common purification methods for products of the Etard reaction?
Common purification methods for Etard reaction products include:
41. How does the presence of a halogen on the aromatic ring affect the Etard reaction?
The presence of a halogen on the aromatic ring can affect the Etard reaction in several ways:
42. Can the Etard reaction be performed under solvent-free conditions?
While the traditional Etard reaction is typically performed in a solvent like carbon disulfide, some modified versions have been developed that can be performed under solvent-free or reduced-solvent conditions. However, these modifications may affect the reaction efficiency and product yield.
43. What is the significance of the chromium(IV) oxidation state in the Etard reaction?
The chromium(IV) oxidation state in chromyl chloride (CrO2Cl2) is significant because:
44. How does the Etard reaction compare to ozonolysis for aldehyde synthesis?
The Etard reaction and ozonolysis differ in several aspects:
45. What are some industrial applications of the Etard reaction?
While the Etard reaction has limited large-scale industrial applications due to environmental concerns, it is still used in some specialized processes:
46. How does the reactivity of naphthalene derivatives compare to benzene derivatives in the Etard reaction?
Naphthalene derivatives generally show different reactivity compared to benzene derivatives in the Etard reaction:
47. Can the Etard reaction be used to synthesize aromatic dialdehydes?
Yes, the Etard reaction can be used to synthesize aromatic dialdehydes from compounds with two methyl groups on the aromatic ring. However, the reaction conditions and stoichiometry need to be carefully controlled to ensure complete oxidation of both methyl groups.
48. What is the effect of using excess chromyl chloride in the Etard reaction?
Using excess chromyl chloride in the Etard reaction can have several effects:
49. How does the Etard reaction behave with sterically hindered methyl groups?
Sterically hindered methyl groups can affect the Etard reaction in several ways:
50. Can the Etard reaction be performed using microwave irradiation?
Yes, some modified versions of the Etard reaction have been developed using microwave irradiation. This approach can offer
