Organic Chemistry: Concepts and Applications

Posted on May 13, 2024 in Chemistry

What is Ozonolysis? with examples?

Ozonolysis is a method of oxidatively cleaving alkenes or alkynes using ozone, a reactive allotrope of oxygen. The process allows for carbon-carbon double or triple bonds to be replaced by double bonds with oxygen. This reaction is often used to identify the structure of unknown alkenes. by breaking them down into smaller, more easily identifiable pieces. Ozonolysis also occurs naturally and would break down repeated units used in rubber and other polymers. On an industrial scale, azelaic acid and pelargonic acids are produced from ozonolysis.

How will you prepare Acetaldehyde and Acetone

Ozonolysis of 2-methyl but -2-ene (C5H1O) Acetaldehyde and Acetone.

of n-Butane

Rotation (of a rear cluster radially) all around the C2-C3 bond like a consequence of torsion angle yields several conformations in n-butane, C1H3 -C2H2-C3H2 -C4H3, which have been expressed in Newman projection formulae as regards:

Conformational of Cyclohexane

One pairing of eclipsed methyls as well as two sets of eclipsed hydroxyl groups make up conformation A. It is also achiral and also has a plane. This would be the n-butane conformation with the most energy, which results from rotation around the C2-C3 bondThe carbon atoms of the chair made up of cyclohexane roughly lie in one plane, and an axis can be drawn perpendicular to this plane.  Each carbon atom of cyclohexane is bonded to two hydrogens. The bond to one of these hydrogen lies in the rough plane of the ring; this hydrogen is called Equatorial Hydrogen. The bond to the other hydrogen atom is parallel to the axis; this hydrogen atom is called Axial Hydrogen. Each of the six carbon atoms of cyclohexane has one equatorial and one axial hydrogen atom,  we have to remember that there are six equatorial hydrogens and six axial hydrogens.

Conformational Analysis of Ethane

Rotation of ethane is barred by a barrier of 12 kJ/mol (2.9 kcal/mol). The conformation with the most stability (low energy) is one in which all of the six C–H bonds are separated from each other as far as possible (seemed staggered when viewed end-on). Carbon–hydrogen bonds are closest to one another when they are worn away with a Newman projection (least stable conformation). Every other conformation lies between these two limits. There are three bond-eclipsing interactions between C and H, so we can assign each interaction a value of about 4.0 kJ/mol (1.0 kcal/mol). A mol of propane has a corresponding energy of 14 kJ (3.4 kcal). 

Homolysis

1. This involves the breaking of a covalent bond symmetrically in such a way that each atom separates with one electron of the shared pair.
2. It deals with neutral particles called free radicals.
3. These reaction are carried out in gas phase or in non-polar solvents.
4. Reaction intermediate are carbon free radicals.

Heterolysis

1. This involves the breaking of a covalent bond disymmetrically in such a way that both the electrons of the shared pair are carried away by one of the atoms.
2. It deals with positive and negative charges called cations and anions respectively.
3. These reaction are carried out in polar solvents.
4. Reaction intermediate are carbocation, carbanion and carbene.

Inductive effect 1 Sigma bonds move the electrons

1. The inductive effect is created by the passage of an electrical charge across a chain of atoms
2. The polarization of bonds causes the inductive effect
3. The degree of inductive impact is affected by the electronegativity values of atoms

Resonance effect 1It is based on conjugation

1. The effect of resonance defines the impact on a molecule’s stability caused by the interaction of pi bond electrons
2. The existence of single and double bonds together causes the resonance effect
3. The resonance effect is affected by the number of double bonds and their order

Nucleophiles 1. They are chemical substances capable of donating electrons to form chemical bonds.

1. A more basic ion is a more reactive nucleophile.
2. They have extra electrons which they can donate. Hence, they are rich in electrons.
3. They are negatively charged hence called anions

Electrophiles 1. They are chemical substances capable of accepting electrons to form chemical bonds.

1. Molecules or ions carrying positive charges make great electrophiles
2. They have a deficiency of electrons; hence, they are ready to accept electrons
3. They are positively charged hence called cations

Huckel’s rule

if a cyclic, planar molecule has 4n+2 π electrons, it is considered aromatic.The best-known example is benzene (C6H6) with a conjugated system of six π electrons, which equals 4n + 2 for n = 1.

Markonvikov’s rule

is that when an unsymmetrical reagent adds to an unsymmetrical alkene, the more positive part of the agent goes to the carbon that has more hydrogen atoms

 Saytzeff’s rule In dehydrohalogenation reactions, the preferred    product is that alkene which has a greater number of alkyl groups attached to the doubly bonded carbon atoms.  Saytzeff’s rule helps to determine the formation of the major alkene in a dehydrohalogenation reaction.When 2-bromobutane is dehydrohalogenated, it produces two products: 1-butene and 2-butene.

an alkyne is an unsaturated hydrocarbon containing at least one carbon-carbon triple bond

how will you prepare acetylene from CaC2

The product manufactured is calcium carbide. It is reacted with water to create acetylene gas, and this reaction can be easily formulated as CaC2 + 2H2O → C2H2 + Ca (OH)2. Acetylene, calcium hydroxide and heat are the byproducts of this reaction.

All possible resonating structure for phenol

Examples of ozonolysis 

aniline is weaker base than cyclohexylamine

The lone pair of electrons on nitrogen in aniline is delocalized due to resonance with benzene ring. Thus, electron density on −NH2 group in aniline is decreased. There is no such effect in cyclohexylamine. Therefore, aniline is a weaker base than cyclohexylamine.

N-butane diagram 

Enantiomers :Two compounds with the exact same connectivity, that are mirror images of each other but that are not identical to each other are called enantiomers. The more common definition of an enantiomer is that it is not superimposable on its mirror image

What is meant by a carbocation?

A carbocation is a molecule in which a carbon atom has a positive charge and three bonds. We can basically say that they are carbon cations. Formerly, it was known as carbonium ion. Carbocation today is defined as any even-electron cation that possesses a significant positive charge on the carbon atom.

Draw resonating structure of Aniline

why dimethylamine is stronger base than methylamine: Due to the more + I effect. + I effect for dimethyl group is more than the methyl group. So dimethylamine is the stronger base

What is hybridization? Discuss the formation of acetylene molecule using concept of hybridization 

When two atomic orbitals combine to form a hybrid orbital in a molecule, the energy of the orbitals of individual atoms is redistributed to give orbitals of equivalent energy. This is known as hybridization. 

i. During hybridization, the sigma bond is formed when one sp orbital overlaps with each carbon atom, and two C-H bonds are formed when the second orbital on each carbon overlaps with the orbital of H.In this, the carbon atom has two 2 orbitals that are half-filled.Here, the p orbitals participate in triple bond formation.Thus, the hybridization of acetylene molecule is sp hybridization 

Hybridization of Ethylene ( C2H4 )C2H4 has an sp2 Hybridization process. In this Hybridization one ‘s’ and two ‘p’ orbitals are mixed to give three new sp2 hybrid orbitals which all are in the same shape and equivalent energies. These three sp2 hybrid orbitals are at an angle of 120 degrees and give a trigonal planar shape. Ethene has two 2CH molecules and 4H molecules. Carbon consists of 6 electrons and hydrogen has 1 electron. During the formation of CH2=CH2, the electronic configuration of carbon in its ground state (1s2 2s2 2p1 2p1) will change to an excited state and change to 1s2 2s1 2px12py1 2pz1. In an excited state, carbon needs an electron to form bonds; one of the electrons from the 2s2 orbital will move to 2pz orbital to give four unpaired electrons. 

The hybridization of methane molecules occurs by mixing one orbital with three p orbitals. Each orbital consists of one unpaired electron. The s and three p orbitals of carbon overlap with the 1s orbitals of hydrogen to form bonds. Thus methane is sp3 hybridized

how will you prepare ethene from ethyl bromide

Ethene from ethyl bromide- by dehydrohalogenation of ethyl bromide CH3CH2Br + KOH (alc) → H2C = CH2 + KBr + H2O

Ethene from Ethanol: Ethene from ethanol- by acidicd ehydration of alcohols.

How propene prepared from propyl bromide

When propyl bromide is reacted with alcoholic KOH then we get propene and this propene converts into propane in presence of H.

How propene prepared from 1-propanol : Dehydrate 1-propanol using a strong acid catalyst to produce propene.

Possible isomers for C3H6O

Possible isomers C4H10

Possible isomers for C4H9Br

Geometric isomers are two or more compounds with the same number and types of atoms, and bonds, but which have different geometries for the atoms. For instance, fumaric acid and maleic acid have the same molecular formula and weight, yet they are not the same molecule.

A chiral centre is an atom that has four different groups bonded to it in such a manner that it has a nonsuperimposable mirror image.

The specific angle to which they rotate the polarized light is the Specific Rotation

possible isomers of C3H8O