Reactions

Dr. M. Abd-Elhakeem

Faculty of Biotechnology

Organic Chemistry

Chapter 3

Is a Chemical reaction in which two molecules or (functional groups) combine to form one single molecule, together with the loss of a small molecule. Usually water molecule.

Condensation

Most common condensation reaction occurs between Carbonyl group and amino group such as condensation between two amino acids to form peptide.

Condensation between hydrazine hydrate or phenyl hydrazine with aldehydes and ketones to form characteristic hydrazones and with

di carbonyl compound to form heterocyclic ring.

Also reaction of alcohols and acids which known as esterification is considered a condensation process because it involves a production of water molecule

is a chemical process in which a certain molecule is split into two parts by the addition of a Molecule of water.

Hydrolysis

Esters and amides shows hydrolysis reactions as illustrated below

CH3

O

O CH3

+ OH2

CH3

OO CH3+

OH CH3

+

CH3

O

OH

OH H

CH3

O

NH CH3

+ OH2 CH3

O

OH

NH2 CH3+

Hydrolysis reactions are very important for our life, where many process in our body involve hydrolysis step such as •1- Hydrolysis of ATP (energy source of human cell) to form ADP and phosphate group that cause releasing energy

+H2O

-H2O

2- Hydrolysis of proteins, fats, oils, and carbohydrates during metabolism to form simple molecules suitable for absorption.

is a process of reacting Monomers together in a chemical reaction to form three-dimensional networks or chains.

Polymers are molecules which consist of a long, repeating chain of smaller units called monomers. Polymers have the highest molecular weight among any molecules, and may consist of billions of atoms.

Polymerization

Polymer: High molecular weight molecule made up of a small repeat unit (monomer).•A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A

Monomer: Low molecular weight compound that can be connected together to give a polymer

Oligomer: Short polymer chain

Copolymer: polymer made up of 2 or more monomers

A-B-B-A-A-B-A-B-A-B-B-B-A-A-B

Polymer SynthesisThere are two major classes of polymer formation mechanisms

1- Addition polymerization: The polymer grows by sequential addition of monomers to a reactive site

Addition PolymerizationIn*

A

InitiationIn A* A

Addition PolymerizationPropagation

In*A

InitiationIn A A* A

Addition Polymerization

Propagation

AIn*A

InitiationIn A A A*

Addition PolymerizationPropagation

nAIn A A A A

nA*

A A A A Am

In A A A AnA

*A A A A Am

Combination

In*A

InitiationIn A A A A*

Termination

200 °C2000 atm

O2

peroxides

polyethylene

H2C CH2

Free-Radical AdditionPolymerization of Ethylene

20

2 -Condensation polymerization

Condensation polymerization: the polymer grows from monomers by splitting off a small molecule such as water or carbon dioxide.

Example: formation of amide links and loss of water

Monomers

First unit of polymer + H2O

Types of Polymers

1- Polyolefins: made from olefin (alkene) monomers2- Polyesters, Amides, Urethanes, etc.: monomers linked by ester, amide, urethane

3- Natural Polymers: Polysaccharides, DNA, proteins

Common PolyolefinsMonomer Polymer

Ethylene

H3CCH3

nRepeat unitPolyethylene

CH3

CH3n

CH3 CH3 CH3 CH3 CH3 CH3CH3Propylene

Polypropylene

PhCH3

n

Ph Ph Ph Ph Ph PhPhStyrene

Polystyrene

ClCH3

n

Cl Cl Cl Cl Cl ClClVinyl Chloride

Poly(vinyl chloride)

F2C CF2

Tetrafluoroethylene

F3C

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

CF3

nPoly(tetrafluoroethylene): Teflon

Polyesters, Amides, and UrethanesMonomer Polymer

CO2HHO2CHO

OHO O

HO OH2C

H2C O

nTerephthalic acid

Ethyleneglycol

Poly(ethylene terephthalate

H

Ester

HO OH

O O

4H2N NH24

Adipic Acid 1,6-Diaminohexane Nylon 6,6HO N

HNH

H

O O

4 4n

CO2HHO2C

Terephthalic acid

NH2H2N

1,4-Diamino benzene

Kevlar

O

HO

OHN

HN H

n

Amide

HOOH

Ethyleneglycol

H2COCN NCO

4,4-diisocyantophenylmethaneSpandex

H2C

HN

HN

O

HO

O

OH2C

H2C O H

n

Urethane linkage

Natural Polymers

Monomer Polymer

Isoprenen

Polyisoprene:Natural rubber

O

H

HO

H

HO

H

HOHH OH

OH

Poly(ß-D-glycoside):cellulose

O

H

O

H

HO

H

HOHH OH

OH

H

n

ß-D-glucose

H3N

O

O

RPolyamino acid:protein

H3N

OHN

R1

OHN

Rn+1

O

OH

Rn+2n

Amino Acid

BaseO

OH

OP

O

O

O

oligonucleic acidDNA

NucleotideBase = C, G, T, A

BaseO

O

OP

O

O

O

DNA

DNA

Type Abbreviation Major Uses

Low-density polyethylene

High-densityPolyethylene

Polypropylene

Poly(vinyl chloride)

Polystyrene

LDPE

HDPE

PP

PVC

PS

Packaging film, wire and cable insulation, toys, flexible bottles housewares, coatings

Bottles, drums, pipe, conduit, sheet, film, wire and cable insulation

Automobile and appliance parts, furniture , cordage, webbing, carpeting, film packaging

Construction, rigid pipe, flooring, wire and cable insulation, film and sheet

Packaging (foam and film), foam insulation appliances, housewares, toys

Phenol-formaldehyde

Urea-formaldehyde

Unsaturated polyester

Epoxy

Melamine-formaldehyde

Electrical and electronic equipment, automobile parts, utensil handles, plywood adhesives, particle board binderSimilar to PF polymer; also treatment of textiles, coatingsConstruction, automobile parts, boat hulls, marine accessories, corrosion-resistant ducting, pipe, tanks, etc., business equipmentProtective coatings, adhesives, electrical and electronics applications, industrial flooring highway paving materials, compositesSimilar to UF polymers; decorative panels, counter and table tops, dinnerware

Type Abbreviation Typical Uses

PF

UF

UP

-

MF

END OF Chapter 3