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Organic ChemistryOrganic Chemistry

Laboratorium Kimia Organik Jurusan Kimia

Fakultas Matematikan dan Ilmu Pengetahuan Alam

Universitas Padjadjaran

2009

Code of Lecture : D10B. 03E0318

The Unit of Semester credits (SKS) : 2 (2-0)

Semester : Fm/1

Day/Time : Thursday, 13.00 14.40 am


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02/03/2011 2

1. Introduction to Organic Chemistry(Orbitals and their role in Covalent Bonding, Isomerism

and stereochemistry)

2. Nomenclature of Organic Compounds

3. Properties of aliphatic and Aromatic Compounds(alkanes, alkenes, alkynes and benzene)

4. Functional Group of Organic Compounds

(alcohol, eter, aldehyde, keton and carbocylic acid and

derivatives)

5. Basic of Spectrofotometry for Identification of Organic

Compounds

(UV-Vis, IR, 1D- and 2D-NMR, MS)

Organic ChemistryOrganic Chemistry


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What is Organic Chemistry?

25 million Organic Compounds1.75 million Inorganic Compounds

Animal and plant matter, Foods, Pharmaceuticals, Cosmetics,

Fertilizers, Plastics, Petrochemicals, Clothing

Alkane Alkenes Alkyne Alcohol Aldehyde KetoneCarbocylic acid &

derivatives

It is defined as the study of hydrocarbons (compounds of

hydrogen and carbon) and their derivatives


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Introduction to Organic Chemistry

Organic Chemistry, Pharmacy-2009. 01 of 50

1. How are organic molecules classified?Be able to classify organic molecules into functional group families.

2. What are the structures of organic molecules?Be able to recognize the main carbon chain in a molecules and identifyconstitutional isomers.

3. How are organic molecules drawn?Be able to convert between structural and condensed or line structures.

4. How are alkanes and cycloalkanes named?Be able to name alkane or cycloalkane from its structure or write thestructure, given the name.

5. What are the general properties of alkanes?Be able to describe such properties as polarity, water solubility,flammability, toxicity, and chemical reactivity.

6. What are the major chemical reaction of alkanes?Be able to describe the products formed in combustion and

halogenation of alkanes.


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The Nature of Organic Molecules

1. Carbon is always tetravalent; it always forms four bonds.



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2. Organic molecules contain covalent bonds.




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3. Organic molecules contain polar covalent bonds when carbon bonds to

an element on far right or far left of the periodic table.




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4. Carbon can form multiple covalent bond by sharing more than two

electrons with a neighboring atom.




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5. Covalently bonded molecules have specific three-dimensional shapes.




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6. Hydrogen, nitrogen, and oxygen are elements most often present inorganic molecules in addition to carbon.


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Families of Organic Molecules: Functional Groups

At last count, there were more than 25 million organic compounds

described in the scientific literatures.

Each compound has unique physical properties (such as melting point

and boiling point) and each has unique chemical properties.

The organic compounds can be classified into families according to their

structural feature and that the chemical behavior of members of a family

is often predictable.

Instead of 25 million compounds there are just a few general families

of organic compounds Functional Group

A part of a larger molecules and is composed of an atom or group of

atoms that has characteristic chemical behavior

The chemistry of an organic molecules, regardless of size and complexity,

is determined by the functional groups it contains.


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Ethylene

Cholesterol

Fig. 2 The reaction of (a) ethylene and (b) cholesterol with hydrogen.

The carbon-carbon double bond functional groups adds two hydrogen atoms in both

cases, regardless of the complexity of the rest of the molecules.


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The Structure of Organic Molecules Hydrocarbons : Organic compounds containing only carbon and

hydrogen

Alkanes, Alkenes, Alkynes, and arenes are hydrocarbons when no other

functional groups are present in their molecules

Alkanes are the one family of organic compounds that contain no

fungctional groups, for alkanes are constructed entirely of carbon andhydrogen atoms joined by single bonds the absence of functional

groups makes alkanes relatively unreactive.


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The Structure of Organic Molecules

Every member of the other families is essentially an alkane in which one

or more hydrogen atoms have been replaced by functional groups.

The families of organic compounds:

Group 1: The hydrocarbons of the first for families.

Group 2: Those whose functional groups contain only single bonds (alkyl

halides, alcohols, ethers, and amines).

Gropu 3: Those whose functional groups contain a carbon-oxygen double

bond (aldehyde, ketones, carboxyclic acids and anhydride, esters,

and amines).


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The Structure of Organic MoleculesAlkanes and Their Isomers

Alkanes: Molecules that contain only carbon and hydrogen, and that haveonly single bond only one possibility structure No Isomers


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If larger numbers of carbons and hydrogens combine ( 4 carbons),

more than one kind of molecules can be formed, straight- and branced-

chains Compounds with the same molecules formula but with

different connections between atoms Isomers


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more than one kind of molecules can be formed, straight- and branced-chains Compounds with the same molecules formula but with



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more than one kind of molecules can be formed, straight- and branced-chains Compounds with the same molecules formula but with


Its important to realize that different constitutional isomers are

completely different chemical compounds.

They have:

different structures

different physical properties ( such as melting point and boiling point)

Potentially different physiological properties


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Its important to realize that different constitutional isomers are

completely different chemical compounds.

They have:

different structures

different physical properties ( such as melting point and boiling point)

Potentially different physiological properties


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Drawing Organic Structures

Drawing Structural Formulas

Time consuming and awkward

Structural FormulaStructural Formula

(A formula that shows how

atoms are connected to

each other)


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Drawing Organic Structures

CondensedCondensed StructureStructure::

A structure in which central atoms and the atoms connected to

them are written as a groups.

Structural Formula Condensed Structure

ConvenienceConvenience Simpler but show the essential information about

which functional groups are present and how

atoms are connected


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The Shapes of Organic Molecules

CondensedCondensed StructuresStructures dont imply any particular three-dimensionalshape of molecules, they only show that compounds (e. g.,

butane) have a continuous chain of four carbon atoms and

indicate the cdonnections between atoms without

specifying geometry

In fact, butane has no one single shape because rotation is possiblearound carbon-carbon single bonds ConformationsConformations

The exact three dimentionalshape of a molecule at any

given instant


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The Shapes of Organic Molecules

An actual sample of butane contains a great many molecules that

are constantly changing shape, however, most of the

molecules have the less crowded extended confomation .

Some possible conformations of butane. There are many other conformations as well.


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Naming Alkanes

In earlier times when relatively few pure organic chemical were

known, new compounds were named at whim of their

discovered.

Urea a crystalline substance first isolated from urine

Morphine a plant extract that's a sedative and is named after

Morpheus (the Greek god of dreams).

NomenclatureNomenclature(A systematic method of naming compounds)

IUPACIUPAC

(International Union of Pure and Applied Chemistry)


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Naming AlkanesIUPAC System for Organic Compounds

Prefic : Where the location of functional groups and other

substituents on the chain.

Root : The overall size of the molecule by telling how manycarbon atoms are present in the longest continuous

chain.

Suffic : Identifies what family the molecules belongs to


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The straight-chain alkanes are named simply by counting thenumber of carbon atom in the chain and adding the family suffix

ane to the root name to give the name of the parent compound.

Naming Alkanes


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Alkyl group : The part of an alkane that remains when one H atom is

removed

Methyl group : -CH3, the alkyl group derived from methane

Ethyl group : -CH2CH3, the alkyl group derived from ethane

n-Propyl group : -CH2CH2CH3, the alkyl group derived by removing a H from

an end carbon of propane

Isopropyl group : -CH(CH3)2, the alkyl group derived by removing a H from

the central carbon of propane

Naming Alkanes


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an end carbon ofpropane


the central carbon ofpropane

Naming Alkanes


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Naming Alkanes

Alkyl group : The part of an alkane that remains when one H atom is

removed

Methyl group : -CH3, the alkyl group derived from methane

Ethyl group : -CH2CH3, the alkyl group derived from ethane


an end carbon ofpropane


the central carbon ofpropane

Some Common Alkyl Groups


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How toWrite the Naming of Branched-chain?

Step 1. Name the main chain

Find the longest continuous chain of carbons present in the molecule and namethe chain using the root for the number of carbons it contain.

Name as a substituted pentane, not

as a substituted butane, because thelongest chain has five carbons.

Step 2. Number the carbon atoms in the main chainBeginning at the end nearer the first branch point, number each carbon atom in

the main chain.

The first (and only) branch occurs at

C2 if we start numbering from the

left, but would occur at C4 if we

started from the right by mistake


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Step 3. Identify and number the branching substituents.

Assign a number to each branching substituent on the main chain accoring to itspoint of attachment.

The main chain is a pentane. There

is one CH3 substituent group

connected to C2 of the chain.

The main chain is a hexane. There

are two substituents, a CH3 and aCH2CH3, both connected to C3 of

the chain.


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Step 4.Write the name as a single word.

Use hyphens to separate the numbersfrom the different prefixes and usecommas to separate numbers ifnecessary.

If two or more different substituentsgroups are present, cite them inalphabeticalorder.

If two or more identical substituentsare present, use one of the prefixesdi-, tri-, tetra- and so forth, but dontuse these prefixes for alphabetizingpurposes.



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2-Methylpentane

(a five-carbon main chain with a 2-methyl substituent)


3-Ethyl-3-methylhexane

(a six-carbon main chain with a 3-ethyl and 3-methyl substituents

cited alphabetically)

3,3-Dimethylhexane

(a six-carbon main chain with two

3-methyl substituents)


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Based on the number of other carbon atom attached to a given

carbon atom, there are four possibility substituent pattern for

carbon, called primary, secondary, tertiary, and quartenary.

Primary carbon

(1r)

Secondary carbon

(2r)

Primarycarbon (1r) : A carbon atom that is bonded to one other carbon atom

Secondarycarbon (2r) : A carbon atom that is bonded to two other carbon atom

Tertiarycarbon (3r) : A carbon atom that is bonded to three other carbon atom

Quaternarycarbon (4r) : A carbon atom that is bonded to four other carbon atom

Tertiary carbon

(3r)

Quternary carbon

(4r)


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Properties of Alkanes

Fig. 4 Boiling and melting points for C1-C15 staight-chain alkanes.

There is a regular increase with molecular size.

Alkanes contain onlynonpolar carbon-carbon and carbon-hydrogen bonds, so

the only intermolecular forces influencing their properties are the weak London

forces


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Properties of Alkanes

Odorless or mild odor, colorless, tasteless. Non-polar; insoluble in water and soluble in non polar

organic solvent.

Less dense than water.

Flammable.

Regular increase in melting and boiling points with

molecular weight.

Not very reactive


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Chemical Reactions of AlkanesCombustion

Alkanes show little chemical affinity for other moleculesand are inert to acids, bases, and most other common

laboratory reagents.

The major reactions are those with oxygen Combustion

and the halogens (Halogenation or Substitution reactions).

Combustion is The chemical reaction ofalkanes with oxygen

occurs during the combustion of fuels in engines or furnaces.

CO2 or/ and CO + H2O Heat and Light


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Chemical Reactions of AlkanesHalogenation


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Cycloalkanes

Cycloalkane is an alkane that contains a ring of carbon atoms Compounds of all ring sizes from 3 through 30 carbon atoms and beyond

have been prepared in the laboratory.

Cyclic and acyclic alkanes are similar in many of their properties, for thecycloalkanes are also non polar molecules.

Because of their cyclic structure, cycloalkane molecules are more rigid

and less flexible than their open-chain counterpart. Rotation is not

possible around the carbon-carbon bonds in cycloalkanes without

breaking open the ring.


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Cycloalkanes

The six-membered cyclohexane ring exist in a puckered, nonplanar shape

known as the chair conformation, in which the carbon atoms have nearlytetrahedral bond angles.

The cyclohexane ring is therefore very stable, and many naturally

occuring and biochemically active molecules contain cyclohexane rings.

The chair conformation of cyclohexane.All bond angles are close to the 109.5r tetrahedral values.


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Drawing and Naming Cycloalkanes

Cycloalkanes are named by a straightforward extension of rules for open-

chain alkanes.

The carbon ring is equivalent to the main chain.

Line structure A shorthand way of representing ring structures aspolygons without showing individual carbon atoms.


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Drawing and Naming Cycloalkanes

Step 1. Use the cycloalkane name as the parent.

Compounds should be named as alkyl-substituted cycloalkanes rather than as cycloalkyl-substituted alkanes. If there is only one substituent on the ring, its not even necessary toasiggn a number since all ring positions are equivalent.

Step 2. Number the substituents.Start numbering at the group that has alphabetical priority and proceed around thering in the direction that gives the second substituents the lowest possible number.

Parent compound: Cyclohexane

Name: Methylcyclohexane

(not cyclohexylmethane)

Name: 1-Ethyl-3-methylcyclohexane(not1-Ethyl-5-methylcyclohexane

1-Methyl-3-ethylcyclohexane1-Methyl-5-ethylcyclohexane)

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