Redox Chemistry - Organic Chemistry

PCC is an oxidizing agent. It converts alcohols to carbonyls, but is not strong enough to convert a primary alcohol into a carboxylic acid. It only converts primary alcohols to aldehydes, and secondary alcohols to ketones. 1-pentanol is a primary alcohol so it will be converted to the aldehyde pentanal.

PCC is an oxidizing agent that reacts with primary and secondary alcohols. However, it is less reactive than potassium permanganate and chromic acid. PCC differs from chromic acid by oxidizing primary alcohols to aldehydes, whereas chromic acid oxidizes primary alcohols and aldehydes to carboxylic acids. The desired product of the reaction given requires that the primary alcohol be oxidized to an aldehyde, so PCC is the best option. is a reducing agent and would have the opposite effect than what is desired, yielding an alkane.

This is a two step reaction. In the first step, an alcohol is substituted for the bromine via an reaction. Next, the alcohol is oxidized into a ketone with , a strong oxidizing agent used almost exclusively for converting alcohols into carbonyls.

has the capability of oxidizing primary alcohols into aldehydes and secondary alcohols into ketones. However, it cannot oxidize aldehydes into carboxylic acids. To do that, we would need a stronger oxidizing agent such as .

First step: PCC oxidizes the primary alcohol to acetaldehyde

Second step: Grignard reagent attacks carbonyl carbon

Third step: Neutralization of the anion forms isoproyl alcohol

is the only compound listed that is not a reducing agent. Pyridinium chlorochromate is a weak oxidizing agent and is often used to oxidize alcohols into carbony compounds. All of the other compounds are similar in that they function as reducing agents.

The reaction given would give an aldehyde. This type of reaction is called an oxidation reaction. Oxidation of a primary alcohol as in the reaction given by PCC (pyridinium chlorochromate) in (dichloromethane) solvent yields an aldehyde. Like chromic acid, PCC oxidizes alcohols. However, PCC only oxidizes primary alcohols one step up to aldehydes and secondary alcohols to ketones. Chromic acid is a harsher oxidant because it will oxidize aldehydes to carboxylic acids. Below is the mechanism for this reaction:

The reaction given would give an aldehyde. This type of reaction is called an oxidation reaction. Oxidation of a primary alcohol as in the reaction given by PCC (pyridinium chlorochromate) in (dichloromethane) solvent yields an aldehyde. Like chromic acid, PCC oxidizes alcohols. However, PCC only oxidizes primary alcohols one step up to aldehydes and secondary alcohols to ketones. Chromic acid is a harsher oxidant because it will oxidize aldehydes to carboxylic acids. Below is the mechanism for this reaction: Below is the mechanism:

PCC can be used to oxidize primary alcohols into aldehydes, or secondary alcohols into ketones. The starting material shown is a secondary alcohol, so the product will be a ketone (a carbonyl () group where the carbonyl carbon is also attached to two other carbons).

is not a reducing agent; peroxides (compounds with the formula R-O-O-R) are oxidizing agents. A very common peroxide is sodium peroxide .

All of the other listed compounds are reducing agents.

produces a trans-alkene from an alkyne whereas produces a cis-alkene. reduces an alkyne all the way down to an alkane. is a strong oxidizing agent.

This is a standard organolithium reaction.

The organolithium product can be thought of as a strong nucleophile. The carbon steals an electron from the lithium to create . From there, the highly reactive carbo-anion is free to attack the ketone at the site of its carbon to form a tertiary alcohol on the cyclohexane.

is the only answer choice that is not an oxidizing agent. In fact, it is a reducing agent because of the lack of oxygen atoms present. This compound adds hydrogen atoms to a compound, thereby reducing it.

Alkenes can be reduced in the presence of and a metal catalyst like platinum to hydrogenate the alkene to give a saturated alkane. The reaction occurs in a heterogeneous solution rather than a homogenous solution. It occurs on the presence of a solid surface of the metal catalyst.

Note that the three carbon-carbon double bonds in the aromatic ring in the presence of the reducing agent does not get reduced because they are extremely stable due to resonance.

is not a reducing agent; peroxides (compounds with the formula R-O-O-R) are oxidizing agents. A very common peroxide is sodium peroxide .

All of the other listed compounds are reducing agents.

produces a trans-alkene from an alkyne whereas produces a cis-alkene. reduces an alkyne all the way down to an alkane. is a strong oxidizing agent.

This is a standard organolithium reaction.

The organolithium product can be thought of as a strong nucleophile. The carbon steals an electron from the lithium to create . From there, the highly reactive carbo-anion is free to attack the ketone at the site of its carbon to form a tertiary alcohol on the cyclohexane.

is the only answer choice that is not an oxidizing agent. In fact, it is a reducing agent because of the lack of oxygen atoms present. This compound adds hydrogen atoms to a compound, thereby reducing it.

Alkenes can be reduced in the presence of and a metal catalyst like platinum to hydrogenate the alkene to give a saturated alkane. The reaction occurs in a heterogeneous solution rather than a homogenous solution. It occurs on the presence of a solid surface of the metal catalyst.

Note that the three carbon-carbon double bonds in the aromatic ring in the presence of the reducing agent does not get reduced because they are extremely stable due to resonance.