What is C alkylation?

What is C alkylation?

C-alkylation is a process for the formation of carbon-carbon bonds. For alkylation at carbon, the electrophilicity of alkyl halides is enhanced by the presence of a Lewis acid such as aluminium trichloride.

What is Enolate alkylation?

Alkylation of Enolates Enolates can be alkylated in the alpha position through an SN2 reaction with alkyl halides. During this reaction an α-hydrogen is replaced with an alkyl group and a new C-C bond is formed. A very strong base, such as LDA, is often used because of its ability to form the enolate completely.

Are Enolates Carbanions?

In carbanion: Delocalized ions. Enolate ions are derivatives of ketones and aldehydes (compounds containing a double bond between carbon and oxygen atoms), from which they can be generated by abstraction of a proton from the carbon atom that is located next to the carbon of the carbonyl group.

What solvent is typically used for making Enolates and why?

Ether solvents like tetrahydrofuran (THF) are commonly used for enolate anion formation. With the exception of sodium hydride and sodium amide, most of these bases are soluble in THF.

How many types of alkylation are there?

Types of Alkylation Reactions Alkylation of an aldehyde or ketone to form C-C bonds (Grignard Reaction) Coupling reaction of an alkylhalide and an organometallic to form a C-C bond (Wurtz reaction) Alkylation of aromatic rings via alkyl halide (Friedel-Crafts alkylation reaction)

What is the difference between alkylation and acylation?

There are two types of Friedel-Crafts reactions, alkylation and acylation. Alkylation reaction add a simple carbon chain to the benzene ring. Acylation adds an acyl group, creating a ketone or aldehyde.

What is Aza Enolate?

Aza enolates (also known as imine anions, enamides, metallated Schiff bases, and metalloenamines) are nitrogen analogous to enolates. When imines get treated with strong bases such as LDA, highly nucleophilic aza enolates are generated. Instead, aza enolates react similarly to enolates, forming SN2 alkylated products.

What is an enol vs Enolate?

The key difference between enols, enolates and enamines is that enols contain a hydroxyl group with an adjacent C=C double bond and enolates contain a negative charge on the oxygen atom of an enol whereas enamines contain an amine group adjacent to a C=C double bond.

What is Aza enolate?

Are enolates strong nucleophiles?

“the conjugate base is always a better nucleophile”. I said enols were good nucleophiles. But their conjugate bases – enolates – are even better. We call this an enolate.

Why are Enolates more useful than enols?

The ketone tautomer is electrophilic and reacts with nucleophiles: The enol tautomer is nucleophilic and reacts with electrophiles. Enolates are synthetically much more useful than enols (although they react analogously). Imine anions and eneamines are synthetic equivalents of enolate anions.

Are Enolates soft or hard nucleophiles?

Enolates can act as nucleophiles at either the carbon or oxygen termini. The oxygen center acts as a hard nucleophiles while the carbon center acts as a soft nucleophile.

What is the difference between O-alkylation and C-alkelation?

O-alkylation is prevalent when the enolate is dissociated C-alkylation is prevalent where ion clustering occurs

How do enolates work?

Enolates can be very tricky to handle. Upon reaction with a base and in the presence of alkyl halide, the carbonyl compounds with α-hydrogens can undergo a reaction to produce a mixture of c-alkylated product or o-alkylated product. This occurs due to the formation of enolate ion as will be seen ahead in the mechanism.

What are the factors that affect alkylation?

O – Alkylation A number of factors such as negative charge density, solvation, cation coordination, strength of electrophile and product stability affect whether the reaction progresses to C – alkylation or to O – alkylation. Often, in most reactions, a mixture is obtained and the ratios vary from reaction to reaction.

What is the reaction between carbonyl and alkyl halide?

Upon reaction with a base and in the presence of alkyl halide, the carbonyl compounds with α-hydrogens can undergo a reaction to produce a mixture of c-alkylated product or o-alkylated product. This occurs due to the formation of enolate ion as will be seen ahead in the mechanism.