chapter 1-continue introduction to organic chemistry

Chapter 1-ContinueChapter 1-ContinueIntroduction to Organic Chemistry

Writing Dot Lewis Structure with Writing Dot Lewis Structure with multiple center atomsmultiple center atomsCarbons will also be the center atom

in the organic molecule◦-C-C-C- chains

Hydrogen is connected to carbon unless it’s an oxyacids (HClO, etc..) or Carbon has no more valence electrons to share

Order of increasing EN◦(least) C N O F (most)

Write a Dot Lewis structure for CH3COOH Total Valence electron:

H = 4 x1 = 4C = 2 x 4 = 8O = 2 x 6 = 12Total = 24

SkeletalC is less electro negative than OO does not bond to O

H C

H

H

C

O

O H

Bonding

C C O

O

H

H

H

H

Total e- = 24

bonding e - = 14

e- lef t = 10

C C O

O

H

H

H

H

Complete Octet

NOT :)) must form multiple bond

C C O

O

H

H

H

H

Total = 24 e-Bonding = 16Nonbonding = 8e- lef t = 0

Correct

ExampleExampleWrite a Dot Lewis Structure for

CH3NH2

VSEPR TheoryVSEPR TheoryVSEPR theory proposes that the

geometric arrangement of terminal atoms, or groups of atoms about a central atom in a covalent compound, or charged ion, is determined solely by the repulsions between electron pairs present in the valence shell of the central atom

VSEPR ThoeryVSEPR ThoeryCommon shape and angles

◦Linear (180o)◦Tetrahedral (109.5o)◦Trigonal planar (120o)

See table 1.2 page 5

ExamplesExamplesComplete the following Dot Lewis

structure by adding the missing lone-pair then predict the bond angles

a.

b.

c.

C C

H

H Cl

H

H C

O

H

C NC

H

H

H

9

Elements in Organic CompoundsElements in Organic Compounds

In organic molecules, carbon atoms bond

• with four bonds.• mostly with H and other C atoms.• sometimes to O, N, S. • sometimes to halogens F, Cl, and

Br.• Table 1.3 page 7

10

Functional groups are• a characteristic feature of organic

molecules that behave in a predictable way.

• composed of an atom or group of atoms.

• groups that replace a hydrogen atom in the corresponding alkane.

• a way to classify families of organic compounds.

Functional GroupsFunctional Groups

AlcoholAlcoholAn alcohol

contains the hydroxyl (-OH) functional group.R-OH

R C

R

R

O H

Functional group

R = H or Carbon group (alkyl)

H3C C

H

H

O H

H3C C

CH3

H

O H

H3C C

CH3

CH3

O H

1o alcohol

2o alcohol

3o alcohol

Types of Alcohol

Writing structural formulas of Writing structural formulas of AlcoholAlcohol

CH4OMolecular formula

CH3OHCondensed formula

C

H

OH

H

H

Structural formualMethanol

Writing structural Formulas of Writing structural Formulas of AlcoholsAlcoholsDraw Lewis structure and condensed

structural formulas for the four alcohol with molecular formula C4H10O. Classify each alcohol as primary, secondary or tertiary. ◦ Hints: Consider the connectivity of the four carbon

atoms; they can be bonded either four in a chain or three in a chain with the fourth carbon as a branch on the middle carbon. Then consider which carbon should connect to OH with having the same molecule

AminesAmines

In amines, the functional group is a nitrogen atom. RNH2, R2NH or R3H |

—N —

H3C N

H

H Methylamine

1o amine

H3C N

CH3

H

H3C N

CH3

CH3

Dimethylamine

2o amine

Trimethylamine

3o amine

ExamplesExamplesDraw structural formulas of the

three secondary amines with the molecular formula C4H11N

Carboxylic AcidsCarboxylic Acids

Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. –COOH

O ║

— C—OH

ExamplesExamplesDraw condensed structural

formulas for the two carboxylic acids with molecular formula C4H8O2

Carboxylic estersCarboxylic estersAn ester contains the carboxyl group between carbon atoms.

–COOR or –CO2R

C

O

O C

Functional group

ExamplesExamplesDraw structural formulas for the

four esters with the molecular formula C4H8O2

20

Learning CheckLearning CheckClassify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, or amide.

1) CH3─CH2─CH2─OH

2) CH3─O─CH2─CH3

3) CH3─CH2─NH2

O O ║ ║

4) CH3─C─OH 5) CH3─C─O─CH3

ExamplesExamplesConsider the formula C4H8O2.

Write the structural formula for this molecular formula with ◦A carboxyl group◦Ketone group and a 2o alcohol group◦An aldehyde and a 3o alcohol group◦A carbon-carbon double bond and a

1o alcohol