Chem33 – Extra Practice for Week 1 nomenclature, lewis dot structures, and bond-line notation

Functional Group Name

Atom Connectivity

Best Lewis Structure

aldehyde R–CHO

(R = H, formaldehyde)

O

CH H

H

C

O

H

carboxylic acid R–CO2H

(R = CH3; acetic acid) CC

OH

O

H

H

H

CC

O

OH

HH

H

Alkyl Halide R–X

ClC

CC

Br

H HHH

H H

Sulfide S-C-S

amine R–NH2

(R = C6H6; aniline)

C

CC

C

CC

NHH

H

H

H

H

H

C

CC

C

CC

NH

H

H

H

H

H

H

Ester

RC(O)OR HC

CO

C

HH

O

C

H

H

H

H H

ketone R–(CO)–R

(R = CH3; acetone) CC

C

O

H

H

HH

H

H

CC

O

CH

HH

HH

H ether

R–O–R (R = CH3CH2; diethyl ether) C

CO

C

H

H

H C

H

H

H

H H H H

CC

OH

HH

CC H

HH

H H H H

H H

CC

CBr

HH

Cl

HH

C C

O

OH

H

H

CC

H H

H

H

H

alcohol R–OH

(R = CH3CH2; ethanol) CC

O

H

H

HH

H H

C OH

HH

HH H

Aromatic hydrocarbons (arene) C6H6

For each compound below, draw the Lewis dot structure and the bond-line drawing. Then build the compound using your model kit and draw the 3-d representation of the structure. 1) Alkanes: When naming alkanes we need to indicate how many carbons are in the longest carbon chain and indicate if there are any substituents. For alkane and halogen substituents we start with the longest chain, and then give the number of the carbon to which each substituent is attached. a) 4-ethyl-3,4-dimethylnonane

b) 3-bromo-2-fluoro-5,6-dimethylheptane

2) Cyclic compounds – ‘cyclo’ indicate the presence of a ring. The suffix ‘ene’ indicate the presence of a double bond. a) cyclohexane chair conformation (we will talk about the different conformations of cyclohexane next week).

cyclo-hexane b) cyclo-hexatriene - What do you notice about the geometry of benzene versus cyclohexane?

cyclo-hexatriene

since all the carbons in benzene are sp2 hybridized, the ring is planar (completely flat) whereas the sp3 hybridization in cyclohexane creates nearly 109 angles at each carbon. c) 1,3-diethylcyclopentane

d) cyclopropane – What do you notice when building the model of cyclopropane compared to larger rings? What conclusions could you draw about the potential reactivity of these molecules? When building a model you probably notice that you really have to force the atoms together in order to make such a small ring – this is the ‘ring strain’ that Prof. Wender mentioned in class, which makes these molecules very reactive.

3) Functional groups – As the name implies, functional groups have a characteristic reactivity. They are indicated by a suffix at the end of a parent chain, after any unsaturation (ene or yne). a) 1-pentanol

b) pentanal (notice that with aldehydes ( indicated by ‘al’ suffix) the oxygen must be terminal by definition, whereas you have to specifically indicate the position of most other functional groups)

c) 2-methylpropan-2-ol (also known as tert-butyl-alcohol) bond-line notation 3-D representation

O

H

d) Cadaverine (which is a toxic and foul-smelling compound produced by protein hydrolysis during putrefaction of animal tissue. The formula NH2(CH2)5NH2. What is the formal name for Cadaverine? 1,5-pentanediamine or pentamethylenediamine.

e) Cinnamic acid (trans-3-phenylprop-2-enoic acid ) is used in flavors, synthetic indigo, and certain pharmaceuticals, though its primary use is in the manufacturing of esters for the perfume industry. Cinnamic acid has a "honey, floral odor" it is a flavor component in the essential oil of cinnamon

O

OH

(E)-3-phenylprop-2-enoic acid The ‘E’ or ‘trans’ prefix on cinnamic acid tells us the orientation of the substituents around the double bond that starts at the 2nd carbon. ‘Trans’ means the highest priority substituents are on opposite sides. We will talk much more about this once we get into isomers. 4) Phenylalanine is one of the essential amino acids - An essential amino acid is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet. Phenylalanine is found naturally in the breast milk of mammals. It is used in the manufacture of food and drink products and sold as a nutritional supplement for its reputed analgesic and antidepressant effects. The IUPAC name for Phenylalanine is 2-amino-3-phenylpropanoic acid. Draw the bond-line drawing and then label the hybridization on each non-hydrogen atom in Phenylalanine.

NH2

O

OHsp2

sp2

sp2

sp2

sp3

sp3

sp3

sp3

(note: each carbon in the phenyl ring is sp2 hybridized)