Organic Chem

Front 1

Trigonal Planar Carbon

Back 1

The molecule shape in which a central atom is bonded to three other atoms lying in a plane at 120 degree angles to one another

Front 2

Molecular formula

Back 2

A formula that shows the actual numbers of different types of atoms present in a molecule

C6H14

Front 3

Empirical formula

Back 3

Gives the simplest ratio of the different types of atoms in the molecule

C3H7

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Structural formula

Back 4

Indicates the shape of the molecules as well as the number of atoms

Front 5

Condensed structural

Back 5

Abbreviates the formula to a single line

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Skeletal structural

Back 6

Front 7

Configurational isomer

Back 7

Isomers that cannot be inter converted by rotation around a single bond

The two compounds cannot be converted into one another because of the restricted rotation around the double bond- they are different compounds with different physical and chemical properties

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Equivalent hydrogen atoms

Back 8

Gives the same H-NMR signal

Non equivalent Hydrogen's gives different H-NMR signals

Front 9

Newman Projection

Back 9

A way to view a molecule by looking along a carbon carbon bond

Short hand way of representing the staggered conformation of a molecule like Ethane

Front 10

Most stable Newman configuration

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Staggered conformation

Minimum torsional strain, when C-H bonds of the other Methyl groups are as far away as possible from the C-H bonds of other Methyl group

Minimum torsional strain

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Eclipsed Conformation

Back 11

There is the maximum torsional energy when C- H bonds of one methyl group are adjacent to the C - H bonds of the other methyl group

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Torsional strain

Back 12

Repulsive interactions between electron clouds of the
C- H bonds on adjacent carbon atoms

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Anti -Conformation - Fully Staggered conformation

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Lowest energy conformation , in which the 2 methyl groups are as far apart as possible with a di-hedral angle of 180 degrees

No strain

Front 14

Gauche - Staggered conformation

Back 14

C2 & C3 bond in the anti conformation gives a staggered conformation called gauche conformation

There is no eclipsing interactions but the gauche still have 4 KJ mol higher than the anti - conformation

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Boiling points of OH

Back 15

The boiling points of the alcohols increase as the number of carbon atoms increases

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Primary Alcohol

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OH group is attached to a carbon atom bonded to only one other carbon

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Secondary Alcohol

Back 17

The OH group is attached to a carbon atom bonded to two other carbon atoms

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Tertiary Alcohol

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The OH group is attached to a carbon atom which is bonded to 3 other carbon atoms

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Nitration of Benzene ring

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Benzene ring + HNO3 ( H2SO4 -catalyst) = Benzene & Nitro group

which can then be transferred into the amine group

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Reduction of Nitrobenzene ring

Back 20

Nitro Benzene ring + H2 = Anilines

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Carbonyl Compounds ( Ketones & Aldehydes ) + OH =

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Hemiacetal

(Ketone & Aldehydes )Carboynyl + OH = Hemiacetal

R-O-C-OH

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Acetal Carbon

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Aldehyde is reacted with an excess of alcohol - hemiacetal is sometimes not isolated - instead a acetal is formed

R-O-C-O-R

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Acid Chloride + Amine =

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The Chloride is substituted by the NH

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Formation of acid chlorides

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Carboxylic Acid + SOCL2 / PCl3 ----------> Acid Chloride

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Alkene ( Double bond ) + H2

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Results in an single bond

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Chair conformations

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Most stable- chair conformation

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Angle strain

Back 27

A molecule suffers angle strain when 1 ore more angles are forced to deviate from the ideal angle, example the deviation from 109 degrees

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Cyclohexanes - 6 membered rings

Back 28

Are strain free due to puckering
No torsional or angle strain

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Chair conformation

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Has 2 kinds of hydrogens

Axial
Equatorial

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Axial Hydrogens

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Point up & down from the ring

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Equatorial Hydrogens

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Point out from the ring

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Ring flipping

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All Axial Hydrogens become Equatorial &
Equatorial Hydrogens become Axial

Front 33

Chair conformation of methyl cyclohexane

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The Equatorial position of Methyl group is favoured

because there are steric interactions

When Methyl group is axial it experiences steric strain from interaction with the axial hydrogens on the same side of the molecule - 1 , 3 - diaxial interactions- thus the equatorial methylcyclohexane is lower in energy

Front 34

1 , 3 diaxial interactions

Back 34

When you have a large group in the axial position , you will get 1 , 3 diaxial interactions

Front 35

How to draw a chair conformation

1.

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1. Draw the structure of the compound using wedge/dotted line & number the carbon atoms

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2. Draw the templates

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2. Draw the two templates that represent the 2 chair conformations & number the carbons

Front 37

Note :

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Carbon atoms can either be UP or DOWN

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Substituents represented on wedges are always positioned UP

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The UP position on an UP carbon of the ring is axial

The UP position on a down carbon of the ring is equitorial

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Substituents on dotted lines are positioned down

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The Down position on a down carbon of the ring is Axial

The down position on an UP carbon of the ring is Equitorial

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Axial substituents

Back 40

Will give rise to steric strain

These conformations will have 1 , 3 - diaxial interactions that gives rise to steric strain

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Stereocentre

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A Tetrahedral atom, most commonly a carbon with 4 different groups bonded to it

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Carbon

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4 Valance electrons & can form 4 single bonds

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Nitrogen

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5 Valence electrons & can form 3 single bonds & have 1 lone pair

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Oxygen

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6 Valence electrons , forms 2 single bonds & have 2 lone pairs

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Single bonds

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Sigma bonds

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sp3 Carbon

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Carbon atom that bonds to other atoms via 4 sigma bonds

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Double bonds

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1 Pi bond &
1 Sigma bond

A consequence of the double bond is restricted rotation - which leads to cis-trans isomerism

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sp2 Carbons

Back 48

Carbon atoms that bond to other atoms via three sigma bonds & one Pi bond

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Tripple bonds

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1 Sigma bond &
2 PI bonds

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sp Carbons

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Carbons that bond to other atoms via 2 sigma bonds & 2 PI bonds

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Bond lenghts

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Double & tripple bonds are stronger than a single bond

The shorter the bond , the stronger the bond

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Geometries about carbon atoms

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Linear : All the groups lie in a straight line , 180 degrees

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Trigonal Planar

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Three groups bonded to a carbon

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Tetrahedral

Back 54

Four groups attached to a carbon