C-C Bond Forming Reactions (Part II)

 C-C Bond Formation Contd...

    4.   Kolbe’s Electrolysis

This is an electrolytic decarboxylation of carboxylic acids. The mechanism involves the formation and coupling of alkyl radicals to form a C-C bond.

5.   Organometallic Reactions

Organometallic compounds possess a nucleophilic carbon atom which reacts with variety of compounds having electrophilic carbons to form C-C bonds. Some of the most common organometallic compounds used are Grignard reagent, organo lithium, organosodium, organozinc, and organocopper reagents.

a.      Reaction with Carbonyl Compounds

b.      Reaction with a,b-unsaturated carbonyl compounds

Organometallic compounds react differently with unsaturated carbonyl compounds. The nucleophilic carbon may attack the carbonyl carbon (direct addition) or the b-carbon (conjugate addition or Michael addition).

 

c.       Reaction with Epoxide

Organometallic compounds opens the epoxide ring.

 

    6.   Claisen Condensation

The self-condensation of esters is known as Claisen condensation. A common example is the acetoacetic ester synthesis.

 

    7.   Cross Coupling Reactions

Some important coupling reactions are Suzuki coupling, Stille coupling, Hiyama coupling, Nigishi coupling, Heck reaction, and Kumada couplings. All of these reactions involve the formation of a single bond between carbon atoms.

The mechanism of these cross coupling reactions involve some common steps, viz. oxidative addition, transmetallation, and reductive elimination.

How to read IR Spectrum? (With Subtitles) | The carbonyl functional grou...

INTERPRETATION OF IR SPECTRUM OF ESTERS

C-C Bond Forming Reactions (Part 1)

One of the most important reactions in organic chemistry are the C-C bond forming reactions. Following are some of the reactions for forming a single bond between carbon atoms.

1.   Aldol Condensation

Aldol condensation is the reaction in which an enolizable aldehyde or ketone condenses with another aldehyde or a ketone to form an aldol followed by dehydration to yield a,b-unsaturated carbonyl compounds. The reaction is carried out under basic or acidic conditions and the prerequisite is the presence of an a-hydrogen in the aldehyde.

The reaction goes through an enolate (base catalyzed) or enol (acid catalyzed) intermediate.

    2.   Wurtz Reaction

Wurtz reaction is the coupling of alkyl groups in alkyl halides in the presence of a metal (Na).

3.   Friedel-Craft’s Alkylation and Acylation

Friedel-Craft’s alkylation and acylation are examples of aromatic electrophilic substitution reactions. It involves the reaction of an aromatic ring with alkyl or acyl halides in the presence of a Lewis acid.

More to Come………..

How to Read IR spectrum? (With subtitles) | Amide | The Carbonyl functio...

How to Read IR spectrum? (With subtitles) | Amide | The Carbonyl functional group

Amides are characterized by the presence of a carbonyl group to which a nitrogen is attached. This nitrogen provides its lone pair for resonance with the carbonyl group, decreasing its double bond character and thus the strength. Therefore, it abosrbs at a lower frequency.

This video lecture explains how we can identify the presence or absence of an amide functional group through IR spectoscopy.

How to Read IR spectrum? (with subtitles) | The carbonyl group | carboxy...

HOW TO READ AN IR SPECTRUM?

IR spectroscopy is sometimes known as "The functional group spectroscopy" because it gives us an idea of which functional groups are present in the molecule.

IR spectrum contains peaks for both stretching and bending vibrations and mostly these are the stretching vibration bands that diagnose the molecule, howevers sometimes the bending vibration bands are also needed for identifiction of certain functional groups.

This video is the first in this series and here we are discussing the carboxylic acid functional group.

Solving Structures with the Help of Spectroscopy

 

The chemical structure of compounds is one of the basic characteristics which a scientist needs to know to further predict its properties and its interaction with other substances, light, and its probability as a potential drug candidate. In the second half of the last century, spectroscopic techniques have flourished so much that scientists and researchers are using them efficiently as a tool for structure determination of compounds. The most frequently used spectroscopic techniques for this purpose are UV/visible, Infrared (IR), Nuclear Magnetic Resonance (NMR), and Mas Spectrometry (MS). Each technique furnishes different information about the structure of the compounds, which may be combined to get to the final structure. Let’s see how useful these techniques are.

Molecular Vibrations (with subtitles) | Fundamental vibrations | IR Spec...

Molecules are always in a state of vibration. The bonds within the molecules vibrate causing a change in either the bond length or the bond angle. The former type is known as the stretching vibration, while the later is called the bending vibrations.