Chemistry: Organic Reaction Types

What does the '2' in the term SN2 signify regarding the reaction mechanism?

The '2' signifies that the reaction is bimolecular, meaning the rate-determining step involves the collision of two species: the substrate and the nucleophile.

According to Markovnikov's rule, where does the hydrogen atom bond in the addition of HX to an unsymmetrical alkene?

The hydrogen atom bonds to the carbon atom that already has the greater number of hydrogen atoms.

What is the primary synthetic use of Sodium Borohydride (NaBH4)?

NaBH4 is a mild reducing agent used to reduce aldehydes and ketones into primary and secondary alcohols, respectively.

What is the specific function of Pyridinium chlorochromate (PCC) when reacting with a primary alcohol?

PCC oxidizes primary alcohols to aldehydes and stops there, preventing further oxidation into carboxylic acids.

Which two major organic reaction mechanisms involve the formation of a carbocation intermediate?

The SN1 (unimolecular nucleophilic substitution) and E1 (unimolecular elimination) mechanisms both proceed through a carbocation intermediate.

Which reagent is considered a stronger reducing agent: NaBH4 or LiAlH4?

LiAlH4 (Lithium Aluminum Hydride) is significantly stronger and can reduce carboxylic acids and esters, which NaBH4 cannot.

Why are polar aprotic solvents, such as DMSO or DMF, preferred for SN2 reactions?

They solvate the counter-cations but not the nucleophilic anions, leaving the nucleophile 'naked' and highly reactive for backside attack.

Describe the stereochemical outcome of an SN2 reaction occurring at a chiral center.

The reaction results in a complete inversion of configuration (Walden inversion) because the nucleophile must attack from the side opposite the leaving group.

What does Zaitsev's rule predict for the major product of an elimination reaction?

It predicts that the most stable alkene, which is the one with the greatest number of alkyl substituents on the double bond, will be the major product.

Why does an SN1 reaction typically result in a racemic mixture of products?

The intermediate carbocation is planar (sp2 hybridized), allowing the nucleophile to attack from either the top or bottom face with equal probability.