Alcohol and Phenol Flashcards
What is the bond angle in alcohols compared to the tetrahedral angle?
Slightly greater than the tetrahedral angle
This is due to the repulsive interaction between bulky R groups.
What is the C-O bond length in alcohols?
Approximately 41 pm
This bond length is almost the same as in alcohols.
How are alcohols prepared from alkenes?
By acid-catalyzed hydration
Alkenes react with water in the presence of an acid catalyst.
According to which rule does the addition reaction occur in unsymmetrical alkenes?
Markovnikov’s rule
This rule dictates the regioselectivity of the addition reaction.
What is the first step in the mechanism of acid-catalyzed hydration of alkenes?
Protonation of alkene to form carbocation
This occurs via electrophilic attack of H2O.
What happens in the second step of the acid-catalyzed hydration mechanism?
Nucleophilic attack of water on carbocation
This step involves the water molecule attacking the positively charged carbocation.
What is the final step in the mechanism of acid-catalyzed hydration to form alcohols?
Deprotonation to form an alcohol
This results in the formation of the alcohol from the carbocation.
Fill in the blank: Alkenes react with water in the presence of _______ to form alcohols.
acid as catalyst
What is hydroboration?
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.
Who reported hydroboration?
HC Brown in 1959.
Brown’s work laid the foundation for understanding hydroboration in organic chemistry.
What is the product of hydroboration of an alkene?
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.
What are the starting materials for the reduction of carbonyl compounds to alcohols?
Aldehydes and ketones.
This reduction can be achieved using catalytic hydrogenation or reagents like sodium borohydride (NaBH4) or lithium aluminium hydride (LiAlH4).
What type of alcohol is obtained from the reduction of aldehydes?
Primary alcohols.
The reduction process involves the addition of hydrogen in the presence of catalysts.
What type of alcohol is obtained from the reduction of ketones?
Secondary alcohols.
Ketones yield secondary alcohols upon reduction.
What is the role of lithium aluminium hydride (LiAlH4) in organic synthesis?
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.
What is the process to reduce carboxylic acids to alcohols commercially?
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.
What catalysts are typically used for the reduction of carbonyl compounds?
Finely divided metals such as platinum, palladium, or nickel.
These catalysts facilitate the addition of hydrogen to carbonyl groups.
Fill in the blank: Aldehydes yield _______ upon reduction.
primary alcohols
Fill in the blank: Ketones yield _______ upon reduction.
secondary alcohols
True or False: The addition of borane to a double bond follows Markovnikov’s rule.
False
Hydroboration results in a product that is contrary to Markovnikov’s rule.
Commercial prep of alcohol from carboxylic acid reaction
RCOOH in presence of R’OH AND H+ gives RCOOR’ which on rexn with h2 and catalyst give RCH2OH + R’OH
What type of alcohol is produced when Grignard reagents react with methanal?
Primary alcohol
Methanal is the simplest aldehyde, leading to the formation of a primary alcohol.
What type of alcohol is produced when Grignard reagents react with other aldehydes?
Secondary alcohol
Other aldehydes lead to the formation of secondary alcohols through Grignard reactions.
What type of alcohol is produced when Grignard reagents react with ketones?
Tertiary alcohol
Ketones react with Grignard reagents to yield tertiary alcohols.
What is the first step in the reaction of Grignard reagents with carbonyl compounds?
Nucleophilic addition to the carbonyl group
This step forms an adduct before further reactions occur.
What happens to the adduct formed in the reaction of Grignard reagents with carbonyl compounds?
Hydrolysis yields an alcohol
The adduct undergoes hydrolysis to produce the final alcohol product.
Complete the reaction: RCHO + RMgX → _______.
RCH(OH)MgX
This reaction illustrates the formation of an alcohol from an aldehyde and a Grignard reagent.
Complete the reaction: RCOR + R’MgX → _______.
R-C(OH)R’ + Mg(OH)X
This reaction shows the production of a tertiary alcohol from a ketone.
What is the general role of Grignard reagents in organic synthesis?
To produce alcohols from carbonyl compounds
Grignard reagents are powerful nucleophiles used to form alcohols by reacting with aldehydes and ketones.
True or False: Grignard reagents can react with both aldehydes and ketones.
True
Grignard reagents are versatile and can react with various carbonyl compounds.
What is the primary source of worldwide phenol production?
Cumene
Cumene (isopropylbenzene) is the main hydrocarbon used for phenol production.
What is the process to obtain phenol from chlorobenzene?
Fused with NaOH at 623K and 320 atmosphere pressure
This process involves the acidification of the produced haloarenes.
How is phenol produced from benzenesulphonic acid?
Benzene is sulphonated with oleum and then converted to sodium phenoxide
The sodium phenoxide is then acidified to yield phenol.
What is the role of sodium hydroxide in phenol production from sulphonated benzene?
Converts benzene sulphonate to sodium phenoxide
This reaction is part of the overall process to obtain phenol.
What is the process to obtain phenol from diazonium salts?
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.
What temperature range is used for forming diazonium salts?
273-278 K
This temperature is critical for the stability of diazonium salts.
What is the method to produce phenol from cumene?
Oxidation of cumene to cumene hydroperoxide, then treated with dilute acid
This reaction also produces acetone as a by-product.
What by-product is formed during the production of phenol from cumene?
Acetone
Acetone is produced alongside phenol during its synthesis from cumene.
Fill in the blank: Phenol is obtained from __________ by acidification.
Sodium phenoxide
Sodium phenoxide is an intermediate in the production of phenol.
True or False: Phenol can be produced by hydrolysing diazonium salts.
True
Hydrolysis of diazonium salts is a recognized method for phenol synthesis.
What is formed when cumene hydroperoxide is treated with dilute acid?
Phenol and acetone
This reaction is a significant industrial process for producing phenol.
