Organic Chemistry

1

Chemistry

Chemistry is the study of the substances, specially their structure, properties, transformations and the energy changes accompanying these transformation.

2

Organic Chemistry

The study of Carbon Compounds or better to say the chemistry of hydrocarbons and their derivatives.

3

ATOMIC STRUCTURE

Atom: Smallest indivisible particle of an element

Molecule: Smallest particle of matter

4

5

Types of BondingIonic bonding

– electron is fully transferred from metal to non-metal

– binding is by electrostatic attraction.

6

Ionic Bonding

Na FSodium Atom Fluorine Atom

7

Ionic Bonding (2)

Na F

Attraction between the two ions is electrostatic -- Ionic Bond

Sodium ion Fluoride ion

8

A SIMPLE COVALENT BOND

H . H.

A pair of electrons is shared between the two bonded atoms.

9

A SIMPLE COVALENT BOND

H H

Bonded pair

10

A LEWIS DIAGRAM

H O H....

H O H. .... ...

COVALENT BONDS

CONSTRUCTEDFROM LEWISDOT SYMBOLS

(note use of lines for bonds)

11

DRAWING CONVENTIONS

1. A shared pair (bond) is drawn as a line.

2. An unshared pair is shown as a pair of dots.

C O

N :3. The diagram includes formal charges (later).

H O H

H

.. +

12

Carbon 4 bondsNitrogen (phosphorus) 3 bondsOxygen (sulfur) 2 bondsHalogen (F, Cl, Br, I) 1 bondHydrogen 1 bond

Bonding patterns

13

Normal bonding patternsCarbon (4 bonds) C C C C

Nitrogen (3 bonds) N(Phosphorus)

N N

Oxygen (2 bonds)

(Sulfur)O O

Halogen (1 bond) X(F, Cl, Br, I)

Hydrogen (1 bond) H

14

Common Bonding Patterns -- Cations

..

..

:

+ + +

++

+ +

+

C N O

N O

N O

N

15

Common Bonding Patterns -- Anions

.. ....

..

..

..

.. :_ _ _

_

_B C N O

N

Types of CarbonsPrimary (1°) – attached to only one other carbon

Secondary (2°) – attached to two other carbons

Tertiary (3°) – attached to three other carbons

Quaternary (4°) – attached to four other carbons

16

HydrocarbonsAliphatic

alkanes – contain only single bonds (saturated)alkenes – contain at least one double bond

(unsaturated)alkynes – contain at least one triple bond

Aromaticcontain a benzene ring

17

Hydrocarbons Alkanes contain only single ( ) bonds and have the

generic molecular formula: [CnH2n+2] Alkenes also contain double ( + ) bonds and have the

generic molecular formula: [CnH2n] Alkynes contain triple ( + 2) bonds and have the

generic molecular formula: [CnH2n-2] Aromatics are planar, ring structures with alternating

single and double bonds: eg. C6H6

18

Types of Hydrocarbons

19

Each C atom is trigonal planar with sp2 hybridized orbitals.There is no rotation about the C=C bond in alkenes.

Each C atom is tetrahedral with sp3 hybridized orbital. They only have single bonds.

Types of Hydrocarbons

20

Each C atom is linear with sp hybridized orbitals.

Each C--C bond is the same length; shorter than a C-C bond: longer than a C=C bond.The concept of resonance is used to explain this phenomena.

Alkanes1 meth methane CH42 eth ethane C2H63 prop propane C3H84 but butane C4H105 pent pentane C5H126 hex hexane C6H147 hept heptane C7H168 oct octane C8H189 non nonane C9H2010 dec decane C10H22

21

22

Naming AlkanesC1 - C10 : the number of C atoms present in the chain.

Each member C3 - C10 differs by one CH2 unit. This is called a homologous series.

Methane to butane are gases at normal pressures.Pentane to decane are liquids at normal pressures.

23

24

Nomenclature of Alkyl Substituents

25

4th Quarter

27

Constitutional Isomers

Substances which have the same molecular formula but a different structural formula.

Isomers differ in connectivity.

Isomerism Molecules which have the same

molecular formula, but differ in the arrangement of their atoms, are called isomers.

Constitutional (or structural) isomers differ in their bonding sequence.

Stereoisomers differ only in the arrangement of the atoms in space. =>

Many things in nature look similar, but they are completely different !

O

OH

HHH

OH

H

OH OH

H

OH

O

HOH

HH

H

OH

OHHOH

OH

O

H

HH

H

OH

H

OH OH

OH

H

O

H

OHH

H

OH

OHH

OH

H

OH

O

OHHH

OH

H

OH H

OH

H

OH

O

H

OHH

H

OH

OHH

OH

H

OH

FIND THE DIFFERENCE!

Isomers

Stereoisomersconnectivity =orientation≠

Constitutionalstructural

connectivity ≠

Diastereomersnot mirror images

EnantiomersNon-superimposable mirror image

Structural Isomers

CH3 O CH3 and CH3 CH2 OH

CH3

CH3

and

=>

33

navedmalek@yahoo.co.in 34

• A compound can have more than one name, but a name must unambiguously specify only one compound

A C7H16 compound can be any one of the following:

Cis-trans isomers are also called geometric isomers.There must be two different groups on the sp2 carbon.

Diastereomers

Functional Groups An atom or group of atoms which makes an organic

compound reactive and decides its functions (properties) is called a Functional group.

In an organic compound, the alkyl group determines the physical properties whereas the functional group determines the chemical properties of the compound.

A Functional group can be introduced by displacing hydrogen of the hydrocarbon.

The functional groups are directly attached to the carbon of the organic compound.

38

The basic structure of testosterone (male hormone) and estradiol (female hormone) is identical.

Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings.

These then interact with different targets in the body.

39

6 functional groups, all hydrophilic hydroxyl group (-OH), a hydrogen atom forms a polar covalent bond with

an oxygen which forms a polar covalent bond to the carbon skeleton.

Because of these polar covalent bonds hydroxyl groups improve the water solubility of organic molecules.

Organic compounds with hydroxyl groups are alcohols and their names typically end in -ol.

40

A carbonyl group (-CO) consists of an oxygen atom joined to the carbon skeleton by a double bond.

If the carbonyl group is on the end of the skeleton, the compound is an aldelhyde.

If not, then the compound is a ketone. Isomers with aldehydes versus ketones have different properties.

41

A carboxyl group (-COOH) consists of a carbon atom with a double bond with an oxygen atom and a single bond to a hydroxyl group.

Compounds with carboxyl groups are carboxylic acids.A carboxyl group acts as an acid because the combined

electro-negativities of the two adjacent oxygen atoms increase the dissociation of hydrogen as an ion (H+).

42

An amino group (-NH2) consists of a nitrogen atom attached to two hydrogen atoms and the carbon skeleton.

Organic compounds with amino groups are amines.The amino group acts as a base because amino groups can pick up

a hydrogen ion (H+) from the solution.Amino acids, the building blocks of proteins, have amino and

carboxyl groups.

43

A sulfhydryl group (-SH) consists of a sulfur atom bonded to a hydrogen atom and to the backbone.

This group resembles a hydroxyl group in shape.Organic molecules with sulfhydryl groups are thiols.Sulfhydryl groups help stabilize the structure of proteins.

44

A phosphate group (-OPO32-) consists of phosphorus bound to four

oxygen atoms (three with single bonds and one with a double bond).

A phosphate group connects to the carbon backbone via one of its oxygen atoms.

Phosphate groups are anions with two negative charges as two hydrogens have dissociated from the oxygen atoms.

One function of phosphate groups is to transfer energy between organic molecules.

45

Functional Groups

navedmalek@yahoo.co.in 46

Functional Groups

navedmalek@yahoo.co.in 47

48

Classes of Organic Compounds

Alkane Alkyl Halide Alcohol

Ether Amine

Alkene Aldehyde Ketone

Carboxylic Acid Ester Amide

Alkyne Nitrile

R H R X R OH

R O R' R NH2

C C

R

R

R

R

R C H

O

R C R'

O

R C

O

OH R C O

O

R' R C NH2

O

C CR R' C NR

ALCOHOL FUNCTIONAL GROUP

R –O H49

Classification

Monohydric Alcohols Polyhydric Alcohols

- Dihydric Alcohols (Ethylene Glycol)- Trihydric Alcohols (Glycerol)

50

Monohydric Alcohols

Devided in Primary, Secondary and tertiary alcohols.

CH3OH, CH3CH2OH Methanol Ethanol CH3CH(OH)CH3 Isopropyl Alcohol CH3C(OH)(CH3) t-Butyl Alcohol

51

Physical Properties

Lower are colorless, neutral substances with characteristic sweet alcoholic smell and burning taste. Higher are waxy solids.

Lower are readily soluble in water & organic solvents but it decreases as M.W. increases.

B.P. are higher than corresponding alkanes. e.g. Methanol-338 K and Methane-112K

52

Preparation of Alcohol By Hydrolysis

R-X + NaOH→ R-OH + NaX By Hydration

CH2=CH2 → CH3CH2OH Hydrolysis of Esters

CH3COOC2H5 → CH3COOH + C2H5OH Reduction of Aldehyde/Ketone

CHO/C=O → 1-Alcohol/2-alcohol Grignard Reagent

R-Mg-X →R-O-MgX →R-OH

53

Chemical properties Displacement of –OH gr. By Halogen(X)

R-OH + HX → RX + H2O Action of Alkali Metals

2ROH + 2Na → 2RONa + H2 Dehydration

C2H5OH → CH2=CH2 + H2O Oxidation of Alcohol(K2Cr2O7/H2SO4)

1-alcohol → Aldehyde → Acid Reduction of Alcohols(Red P )

C2H5OH + 2HI → CH3CH3+H2O + I2

54

METHANOL

Methanol (methyl alcohol) or wood alcohol a. Made by the destructive distillation of wood b. Or by… CO + 2H2 CH3OH c. Used as a solvent d. Possible replacement f or gasoline e. Forms formaldehyde in body causing blindness

CH

OH

HH

55

ETHANOLEthanol (ethyl alcohol) or grain alcohol a. Made f rom the f ermentation of grain, f ruit, or sugar b. C6H12O6 + yeast 2C2H5OH + CO2 c. The alcohol that is in beverages d. Added to automotive fuels – 10% as gasohal e. 1 pint of pure alcohol will kill most people f . caused deterioration of the liver, memory loss

and is harmful to unborn babies

56

HC C OH

H

H

H

H

ISOPROPYL ALCOHOL

57

CC C

OH

HH

H

H

HH

H

I sopropyl alcohol (rubbing alcohol) a. Alcohol used for cuts and cleaning b. Will not be absorbed by the skin c. Toxic if taken internally d. Sold as a 70% solution – 140 proof

58

Ethylene glycol a. Used f or antif reeze in cars b. Very sweet tasting c. Toxic – caused kidney failure and death

C CH

HH

H

OH OHLiver C C

OH OH

OOKidney CaC2O4

Oxalic acid Calcium Oxalate

C C

HH

HH

OH OH

Ethylene glycol

GLYCEROL

59

Glycerol a. Used in lotion to keep skin soft b. Food additive that keeps cookies soft c. Can add to nitric acid to form nitroglycerin

Nitroglycerin (nitro) taken to relieve angina heart pain

C C CH

H

OHOH

HHH

OH

Carbonyl CompoundsIf an oxygen atom is attached to carbon by a double bondthe functional group –C=O is called carbonyl group.

60

ALDEHYDER C H

O

61

Physical Properties

Formaldehyde is a gas at room temp. All other members are colorless liquids at ordinary temp. The higher members are solids.

Lower aldehydes have unpleasant smell but as one goes up in the series the smell becomes more fruity. Ketones are generally pleasant smelling liquids.

Solubilities Lower members are highly soluble in water. Solubilities

decreases with increasing molecular mass. B.P. are higher than those of non polar alkanes. B.P. of aldehydes/Ketones are lower than the B.P. of

alcohols.

62

Chemical Properties Addition Across C=O bond

CH3CHO + HCN CH3CH(CN)OH CH3CH(OH)COOHAcetaldehyde Cyanohydrins 2-hydroxy propanoicAcid -

Addition of Grignard ReagentHCHO + CH3MgBr HCH(OMgBr)CH3 CH3CH2OH + Mg(OH)Br

With Hydroxyl AmineCH3CHO + H2NOH CH3CH=N-OH + H2O

With Hydrazine (Phenyl Hydrazine)CH3CHO + H2NNH2 CH3CH=NNH2 + H2O

OxidationCH3CHO CH3COOH

Reduction (Pt / Ni)

CH3CHO + H2 CH3CH2OH

63

Ketones

64

C

O

R R

ACETONE

65

A c e t o n ea . M a d e f r o m I s o p r o p y l a l c o h o l

b . U s e d a s a s o l v e n t f o r f a t s , r u b b e r , p l a s t i c s , a n d v a r n i s h e sc . U s e d a s f i n g e r n a i l p o l i s h r e m o v e rd . W i l l n o t m i x w i t h w a t e rW a s h e s w a t e r o f f o f g la s s w a r e a f t e r c le a n in g

C

O

CH 3 C H 3CH 3 C H C H 3

O H - H

C

O

CH3 CH3

CARBOXYLIC ACID

66

C

O

R OH R COOH

Physical Properties The first nine mono carboxylic acids are colorless liquids, while

the higher ones are colorless wax like solids. Solubility: The first four (formic, acetic, propeonic, butiric) are

soluble while fifth (valeric) is slightly soluble and acids above six carbon are insoluble in water.

B.P. & M.P.: They have abnormally high b.p., even higher than those of alcohols of similar molecular weights.

67

Chemical PropertiesReaction with alkaliesR-COOH + NaOH R-COONa + H2ODecarboxylationCH3COOH + NaOH soda lime CH3COONa + H2OCH3COONa + NaOH sodalime CH4 + Na2CO3ReductionR-COOH LiAlH4/ 2H2 R-CH2OHReaction with CarbonatesR-COOH + Na2CO3 R-COONa + H2O + CO2Dehydration2R-COOH R-COOCOCH3 + H2O Acid Anhydride

68

FORMIC ACID

69

Formic Acida. Irritant to skinb. Part of the venom in ants, bee’s, or wasps

C

O

H OH

ACETIC ACID

70

The acid in vinegar

C

O

CH3 OH

BENZOIC ACID

71

Benzoic acid Used to make benzene type compounds in organic synthesis

C

O

OH

ESTERS

72

R C

O

O R

73

O

O

Apricot (pentyl buterate)

74

O

O

Orange (Octyl acetate)

75

OC

O

CH3 Jasmine (benzyl acetate)

76

OH

C

O

O CH3 Wintergreen (methyl salicylate)

ETHER

77

R O R

Diethyl ether a. Used as a solvent b. Used for thinning paints c. Boils at 36 C (dries quickly) d. Used as anesthetic or as a drug e. Dissolves organic compounds readily f. Reacts with oxygen to form unstable peroxides

O

DIETHYL ETHER

78

Tert-butyl ether (MTBE)a. Gasoline additiveb. Reduces CO emissionsc. Replaced lead as the antiknock compound

TERT-BUTYL ETHER

79

CH3 O C

CH3

CH3

CH3

ETHYLENE OXIDE

80

Ethylene Oxidea. Very toxic gasb. Used in the formation of ethylene glycolc. Ethylene glycol is used in antifreeze and in polyester fibers.

CCO

H

HH

H

AMINES

81

N H

H

H

N H

H

R

N R

H

R

N R

R

R

primary

secondary

tertiary

amonia

82

CH2 N H

HCH2 Amphetamine (stimulant drug)

83

Analine (used in dyes)N H

H

84

N CH3

H

CH3

Dimethyl amineused in volcanizing rubber, tanning hydesand making of soaps

85

N CH2CH3

CH2CH3

CH3CH2Triethyl amineattracts insectswarning agent in natural gas

Proteins

Protein Basics Made of C,H,O, N SPONCH Monomers = amino acids

- 20 different types of amino acids used to make proteins

Proteins are the polymer also called a polypeptide

Meet the monomer –Amino acid

3 main parts - Amino group NH2

- Carboxyl group COOH - R group (side chain) each of the 20 types of amino acids have a unique R group

Proteins form from chains of amino acids

Protein

Proteins vary in length – can be 1,000s of amino acids long

Proteins Shape A protein’s shape is determined by the

order that amino acids are joined in The shape of a protein determines its

function

Hemoglobin antibody enzymes polymerase

Four Levels of Structure allow for any shape

2-28

Protein Structure

Protein Structure – Primary Structure Primary structure is the order of the

amino acids that make up a protein. - the interactions of the R groups on

each amino acid cause the molecule to bend and fold –

different arrangements create different shapes

- as a result- the order of amino acids determines the shape of the protein - shape determines function - changing a single amino acid can

change a protein’s shape.

Protein Structure- Secondary Structure The folding proteins often assume one

of two general shapes – pleated sheets or an alpha helix these

are the protein’s secondary structure. - hydrogen bonds between amino acids

stabilize the secondary structure

Alpha Helix

Protein Structure – Tertiary Structure The coiled or pleated structures

continue to fold until they form a complex three

dimensional structure. - most proteins are completed at this

stage and are fully functioning proteins.

Remember: Shape determines function

Protein Shape-Quaternary Structure

Some more complex proteins are assembled from two

or more protein molecules. - Insulin – 2 forms – 2 proteins or 6

proteins - Hemoglobin – 4 proteins

Protein Functions Proteins are the Worker Molecules of Living Things

Enzymes - proteins that allow chemical reactions to occur in living things Antibodies – proteins that protect the body from

infection Structure – cytoskeleton, hair, nails, muscles, spider

web, silk, feathers ,horns, hooves etc…. Hormones – chemical messengers Cell membrane – proteins can act as channels through

the cell membrane - receptor proteins found on membrane transmit signals to the inside of cells

Hemoglobin – protein found in blood that carries oxygen

Proteins can be Denatured Denatured proteins are proteins that lose

their shape - if they lose their shape, they also lose

their - What can cause a protein to become

denatured? Exposure to: A Strong Acid A Strong Base Heat An organic solvent: Alcohol

or Acetone - Denatured proteins can lose quaternary,

tertiary and secondary structure - Primary Structure is left untouched

Denatured Proteins

Vocabulary for the Protein Pro Polypeptide R – Group Peptide Bond Primary Structure Secondary Structure Tertiary Structure Quaternary

Structure Enzymes Antibodies

Cell Membrane Proteins

Hormones Denatured Protein 4 things that

denature proteins