Aldehida dan Keton 2/2

Summary

This transcript provides an in-depth discussion on the chemistry of aldehydes, ketones, and alcohols, focusing on their properties and synthesis methods. It covers topics like solubility in water, boiling points, and the ability to form hydrogen bonds. The script also delves into various reactions to produce aldehydes and ketones, such as oxidation of alcohols, dehydrogenation, and the use of reagents like potassium permanganate and chromium salts. Additionally, the script touches on industrial-scale methods for generating these compounds, highlighting key reactions like Friedel-Crafts acylation and the role of catalysts in producing aldehydes and ketones efficiently.

Takeaways

• 😀 Aldehydes and ketones are soluble in water due to hydrogen bonding with the water molecules, but the solubility decreases as the carbon chain length increases beyond C4.
• 😀 The boiling point of ketones is higher than that of alkanes due to dipole-dipole interactions, but lower than alcohols, since aldehydes and ketones cannot form hydrogen bonds between molecules.
• 😀 The boiling point of a substance is influenced by its ability to form hydrogen bonds between molecules, which is more pronounced in alcohols than in ketones.
• 😀 Aldehydes and ketones can be synthesized by oxidizing alcohols: primary alcohols yield aldehydes, and secondary alcohols yield ketones.
• 😀 Oxidation reactions with potassium dichromate or permanganate can be used to convert ethanol into acetaldehyde and 2-propanol into acetone.
• 😀 In certain reactions, secondary alcohols can be oxidized with acetone and a catalyst to form ketones (e.g., the formation of diethyl ketone).
• 😀 Aldehydes and ketones can also be produced via dehydrogenation reactions at high temperatures in industrial processes, using catalysts like copper.
• 😀 Alkynes can react with water to form aldehydes or ketones depending on the specific alkyne used, following Markovnikov's rule.
• 😀 In reactions involving alkenes and ozone, products like aldehydes and ketones can be formed, with products determined by where the double bond is cleaved.
• 😀 The reduction of acyl halides with palladium catalysts can produce aldehydes, while ketones are not typically produced in this reaction.

Q & A

What is the solubility of aldehydes and ketones in water?

Aldehydes and ketones with carbon chains around C4 or C5 are soluble in water due to the hydrogen bonding formed between the carbonyl group and water molecules. However, as the carbon chain length increases, the solubility decreases.

Why do aldehydes and ketones have higher boiling points than alkanes but lower than alcohols?

Aldehydes and ketones have higher boiling points than alkanes because of dipole-dipole interactions between molecules due to the polar carbonyl group. However, their boiling points are lower than alcohols because aldehydes and ketones cannot form hydrogen bonds between their molecules, unlike alcohols.

What happens when primary and secondary alcohols undergo oxidation?

When primary alcohols are oxidized, they form aldehydes, whereas secondary alcohols produce ketones. Potassium permanganate and potassium dichromate are common oxidizing agents used in these reactions.

What is the role of potassium dichromate in the oxidation of alcohols?

Potassium dichromate acts as an oxidizing agent, facilitating the oxidation of primary alcohols into aldehydes and secondary alcohols into ketones. The reaction typically occurs in an acidic environment.

How does dehydrogenation of alcohols contribute to aldehyde production?

Dehydrogenation of alcohols involves the removal of hydrogen atoms, typically in the presence of a copper catalyst at high temperatures, to produce aldehydes, particularly from primary alcohols. This process is commonly used in industrial settings.

What is the outcome when alkynes undergo hydration reactions?

When alkynes undergo hydration reactions using mercury(II) sulfate and sulfuric acid, they form aldehydes or ketones, depending on the structure of the alkyne.

What are geminal dihalides, and how do they contribute to aldehyde or ketone formation?

Geminal dihalides are compounds with two halogen atoms attached to the same carbon atom. When hydrolyzed in a basic environment, geminal dihalides can yield aldehydes (from terminal dihalides) or ketones (from non-terminal dihalides).

What is the process of pyrolizing calcium carboxylates, and what does it yield?

Pyrolysis of calcium carboxylates involves heating the compound to high temperatures, leading to the formation of ketones, such as acetone, along with calcium carbonate as a by-product. This reaction is commonly used in industrial-scale production.

How does the reduction of acid halides produce aldehydes?

Acid halides, such as acyl chlorides, can be reduced with hydrogen in the presence of palladium catalysts to form aldehydes. This is known as the Rosenmund reduction, a method commonly used to produce aldehydes from acid halides.

What is the significance of Friedel-Crafts acylation in the formation of aldehydes and ketones?

Friedel-Crafts acylation is a reaction in which an acyl group (RCO) is added to an aromatic ring, forming compounds like benzophenone. This reaction uses a catalyst like AlCl3 and is important in the synthesis of aromatic aldehydes and ketones.