Organic Structure

• Among neutral (uncharged) organic compounds – carbon: four covalent bonds and no unshared pairs of electrons – hydrogen: one covalent bond and no unshared pairs of electrons – nitrogen: three covalent bonds and one unshared pair of electrons – – oxygen: two covalent bonds and two unshared pairs of electrons a halogen: one covalent bond and three unshared pairs of electrons

Models

• • • • • • • • Draw a lewis structure, make the model, draw ther 3-D structure, and decribe the bond angles for the following: C 2 H 6 C 2 H 4 C 2 H 2 C 2 H 5 Cl C 2 H 4 O CH 2 O CH 5 N

Alcohols • Alcohol:

contains an OH (hydroxyl) group bonded to a tetrahedral carbon atom

R R-C-O-H R H H H-C-C-O-H H H CH 3 CH 2 OH

–

Function al group (R = H or carbon goup S tructural formula Cond ensed stru ctural formu la

(3°)

H H CH 3 -C-OH H A 1° alcohol CH 3 -C-OH CH 3 A 2° alcohol CH 3 CH 3 -C-OH CH 3 A 3° alcoh ol

Alcohols • Problem:

Draw Lewis structures, make the model, and describe the geometry and polarity for the two alcohols of molecular formula C 3 H 8 O

Alcohols

• • Problem: draw Lewis structures and condensed structural formulas for the two alcohols of molecular formula C 3 H 8 O Solution:

Lew is stuctu res H H H H-C-C-C-O-H H H H H H : O : H H C-C-C-H H H H Cond ensed stru ctural formulas CH 3 CH 2 CH A p rimary alcohol OH 2 CH 3 CHCH 3 OH A secon dary alcohol

Amines • Amine: group

a compound containing an

amino

– the amino group may be primary (1°), secondary (2°), or tertiary (3°)

CH 3 NH 2 Methylamin e (a 1° amine) CH 3 NH or (CH 3 ) 2 NH CH 3 D imethylamin e (a 2° amine) CH 3 NCH 3 or (CH 3 ) 3 N CH 3 Trimethylamin e (a 3° amine)

Amines

– Problem: Draw Lewis structures, make the model, and describe the geometry and polarity for the two primary amines of molecular formula C 3 H 9 N

Amines

– Problem: draw condensed structural formulas for the two primary amines of molecular formula C 3 H 9 N – Solution:

C-C-C-NH 2 NH 2 C-C-C Th e three carbon s may be bond ed to n itrogen in tw o w ays CH 3 CH 2 CH 2 NH 2 CH 3 NH 2 CHCH 3 Add s even hydrogens to give each carbon four b on ds an d give the correct molecu lar formula

Aldehydes and Ketones

• Both contain a C=O (carbonyl) group – aldehyde: contains a carbonyl group bonded to a hydrogen; in formaldehyde, the simplest aldehyde, the carbonyl group is bonded to two hydrogens – ketone: contains a carbonyl group bonded to two carbon atoms

R R O C-C-H O CH 3 CH R Fun ctional grou p A cetaldeh yde (an aldehyde) R R O R C-C-C R R Functional group R O CH 3 CCH 3 Acetone (a ketone)

Aldehydes and Ketones

– Problem: Draw Lewis structures, make the model, and describe the geometry and polarity for the two aldehydes of molecular formula C 4 H 8 O

Aldehydes and Ketones

– Problem: draw condensed structural formulas for the two aldehydes of molecular formula C 4 H 8 O • Solution:

O CH 3 CH 2 CH 2 CH or CH 3 CH 2 CH 2 CHO O CH 3 CHCH CH 3 or CH 3 CHCHO CH 3

Carboxylic Acids • Carboxylic acid:

a compound containing a -COOH (carboxyl: carb onyl + hydr oxyl ) group • in a condensed structural formula, a carboxyl group may also be written -CO 2 H.

O RCOH Fu nctional group O CH 3 COH Acetic acid (a carb oxylic acid )

Carboxylic Acids

– Problem: Draw Lewis structures, make the model, and describe the geometry and polarity for the single carboxylic acid of molecular formula C 3 H 6 O 2

Carboxylic Acids

– Problem: draw a condensed structural formula for the single carboxylic acid of molecular formula C 3 H 6 O 2 • Solution: the only way the carbon atoms can be written is three in a chain; the -COOH group must be on an end carbon of the chain

O CH 3 CH 2 COH or CH 3 CH 2 COOH