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Org > Alcohol and Phenol > Flashcards

Alcohol and Phenol Flashcards

1
Q

What is the bond angle in alcohols compared to the tetrahedral angle?

A

Slightly greater than the tetrahedral angle

This is due to the repulsive interaction between bulky R groups.

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2
Q

What is the C-O bond length in alcohols?

A

Approximately 41 pm

This bond length is almost the same as in alcohols.

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3
Q

How are alcohols prepared from alkenes?

A

By acid-catalyzed hydration

Alkenes react with water in the presence of an acid catalyst.

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4
Q

According to which rule does the addition reaction occur in unsymmetrical alkenes?

A

Markovnikov’s rule

This rule dictates the regioselectivity of the addition reaction.

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5
Q

What is the first step in the mechanism of acid-catalyzed hydration of alkenes?

A

Protonation of alkene to form carbocation

This occurs via electrophilic attack of H2O.

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6
Q

What happens in the second step of the acid-catalyzed hydration mechanism?

A

Nucleophilic attack of water on carbocation

This step involves the water molecule attacking the positively charged carbocation.

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7
Q

What is the final step in the mechanism of acid-catalyzed hydration to form alcohols?

A

Deprotonation to form an alcohol

This results in the formation of the alcohol from the carbocation.

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8
Q

Fill in the blank: Alkenes react with water in the presence of _______ to form alcohols.

A

acid as catalyst

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9
Q

What is hydroboration?

A

A chemical reaction where borane is added to a double bond, resulting in alcohol formation opposite to Markovnikov’s rule.

Hydroboration typically involves the addition of boron to the carbon atom with more hydrogen atoms.

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10
Q

Who reported hydroboration?

A

HC Brown in 1959.

Brown’s work laid the foundation for understanding hydroboration in organic chemistry.

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11
Q

What is the product of hydroboration of an alkene?

A

An alcohol that appears to have been formed by the addition of water to the alkene.

This reaction is notable for its regioselectivity, contrary to Markovnikov’s rule.

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12
Q

What are the starting materials for the reduction of carbonyl compounds to alcohols?

A

Aldehydes and ketones.

This reduction can be achieved using catalytic hydrogenation or reagents like sodium borohydride (NaBH4) or lithium aluminium hydride (LiAlH4).

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13
Q

What type of alcohol is obtained from the reduction of aldehydes?

A

Primary alcohols.

The reduction process involves the addition of hydrogen in the presence of catalysts.

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14
Q

What type of alcohol is obtained from the reduction of ketones?

A

Secondary alcohols.

Ketones yield secondary alcohols upon reduction.

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15
Q

What is the role of lithium aluminium hydride (LiAlH4) in organic synthesis?

A

It is a strong reducing agent used to reduce carboxylic acids to primary alcohols.

It is also used to convert aldehydes and ketones to their corresponding alcohols.

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16
Q

What is the process to reduce carboxylic acids to alcohols commercially?

A

Convert them to esters followed by reduction using hydrogen in the presence of a catalyst.

This method is preferred due to the high cost of lithium aluminium hydride.

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17
Q

What catalysts are typically used for the reduction of carbonyl compounds?

A

Finely divided metals such as platinum, palladium, or nickel.

These catalysts facilitate the addition of hydrogen to carbonyl groups.

18
Q

Fill in the blank: Aldehydes yield _______ upon reduction.

A

primary alcohols

19
Q

Fill in the blank: Ketones yield _______ upon reduction.

A

secondary alcohols

20
Q

True or False: The addition of borane to a double bond follows Markovnikov’s rule.

A

False

Hydroboration results in a product that is contrary to Markovnikov’s rule.

21
Q

Commercial prep of alcohol from carboxylic acid reaction

A

RCOOH in presence of R’OH AND H+ gives RCOOR’ which on rexn with h2 and catalyst give RCH2OH + R’OH

22
Q

What type of alcohol is produced when Grignard reagents react with methanal?

A

Primary alcohol

Methanal is the simplest aldehyde, leading to the formation of a primary alcohol.

23
Q

What type of alcohol is produced when Grignard reagents react with other aldehydes?

A

Secondary alcohol

Other aldehydes lead to the formation of secondary alcohols through Grignard reactions.

24
Q

What type of alcohol is produced when Grignard reagents react with ketones?

A

Tertiary alcohol

Ketones react with Grignard reagents to yield tertiary alcohols.

25
Q

What is the first step in the reaction of Grignard reagents with carbonyl compounds?

A

Nucleophilic addition to the carbonyl group

This step forms an adduct before further reactions occur.

26
Q

What happens to the adduct formed in the reaction of Grignard reagents with carbonyl compounds?

A

Hydrolysis yields an alcohol

The adduct undergoes hydrolysis to produce the final alcohol product.

27
Q

Complete the reaction: RCHO + RMgX → _______.

A

RCH(OH)MgX

This reaction illustrates the formation of an alcohol from an aldehyde and a Grignard reagent.

28
Q

Complete the reaction: RCOR + R’MgX → _______.

A

R-C(OH)R’ + Mg(OH)X

This reaction shows the production of a tertiary alcohol from a ketone.

29
Q

What is the general role of Grignard reagents in organic synthesis?

A

To produce alcohols from carbonyl compounds

Grignard reagents are powerful nucleophiles used to form alcohols by reacting with aldehydes and ketones.

30
Q

True or False: Grignard reagents can react with both aldehydes and ketones.

A

True

Grignard reagents are versatile and can react with various carbonyl compounds.

31
Q

What is the primary source of worldwide phenol production?

A

Cumene

Cumene (isopropylbenzene) is the main hydrocarbon used for phenol production.

32
Q

What is the process to obtain phenol from chlorobenzene?

A

Fused with NaOH at 623K and 320 atmosphere pressure

This process involves the acidification of the produced haloarenes.

33
Q

How is phenol produced from benzenesulphonic acid?

A

Benzene is sulphonated with oleum and then converted to sodium phenoxide

The sodium phenoxide is then acidified to yield phenol.

34
Q

What is the role of sodium hydroxide in phenol production from sulphonated benzene?

A

Converts benzene sulphonate to sodium phenoxide

This reaction is part of the overall process to obtain phenol.

35
Q

What is the process to obtain phenol from diazonium salts?

A

Diazonium salts are hydrolysed by warming with water or treating with dilute acids

A diazonium salt is formed by treating an aromatic primary amine with nitrous acid.

36
Q

What temperature range is used for forming diazonium salts?

A

273-278 K

This temperature is critical for the stability of diazonium salts.

37
Q

What is the method to produce phenol from cumene?

A

Oxidation of cumene to cumene hydroperoxide, then treated with dilute acid

This reaction also produces acetone as a by-product.

38
Q

What by-product is formed during the production of phenol from cumene?

A

Acetone

Acetone is produced alongside phenol during its synthesis from cumene.

39
Q

Fill in the blank: Phenol is obtained from __________ by acidification.

A

Sodium phenoxide

Sodium phenoxide is an intermediate in the production of phenol.

40
Q

True or False: Phenol can be produced by hydrolysing diazonium salts.

A

True

Hydrolysis of diazonium salts is a recognized method for phenol synthesis.

41
Q

What is formed when cumene hydroperoxide is treated with dilute acid?

A

Phenol and acetone

This reaction is a significant industrial process for producing phenol.

Org (5 decks)

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