Hydrocarbon Derivatives

Aldehydes, Ketones, Carboxylic Acids, & Esters

Carbonyl Group

• >CO

• Oxygen attached to a carbon by a double covalent bond.

• Strong dipole

AlAldehydes

• General formula: RCH or RCHO• Carbonyl group is alwaysalways at the end of the

aldehyde (C on one side, H on the other).• Find the name of the alkane with the same

# of carbons. Change the final e to -alal.• Never need #’s for aldehydes – always at

end.

O

HCO H

=

OH

H HCH

Aldehyde comes from

Alcohol Dehydrogenated

HCH

OMethanal

H HCCH H

OEthanal= acetaldehyde

Common name = formaldehyde

1 metabolic product of ethanol on its route to acetic acid.

Acetaldehyde

• Evidence that it is carcinogenic.• Natural component of many ripe fruits.• Contributes to odors of rosemary, daffodil,

bitter orange, camphor, angelica, fennel, mustard, & peppermint.

• A component of cigarette smoke.

CH3CH2CH2CHO Ends in CHO so it’s an aldehyde.

4 Carbons so base name is butane.

Drop final -e and add –al butanal.

Properties of Aldehydes

C=OR

H

C=OR

H

++

-- -

++

Aldehydes are polar! Bumps up the boiling point.

1-way Hydrogen bonding in H2O. Bumps up solubility.

H HO

+

-

Ketones• Carbonyl group , >C=O, located withinwithin a C chain

instead of at the end.• General Format:

R and R' may or may not be the same.

RCR'

=O

Naming Ketoneones

• Nearly always have a number.• Take the corresponding alkane name.• Drop final –e. • Add –one.• Number in front gives location of >C=O.

(Lowest possible #.)

H O HHCCCH H H

= 2-propanone

Common name = acetone

CH3CH2CH2CCH3

=O

2-pentanone

Aldehydes & Ketones

• Known for appealing tastes & smells.• Used as flavorings in food & candy.• Used as fragrances in perfumes.• Vanilla & cinnamon = aldehydes

Properties of Aldehydes & Ketones

• Aldehydes & ketones contain C=O group, which makes the molecules polar.

• Boiling point: Higher than alkanes, lower than alcohols.

• In pure aldehydes & ketones, hydrogen bonding does NOT occur. No H bonded to O.

• Can have 1-way Hydrogen bonding in water, so they are pretty soluble in H2O.

Carboxylic Acids

• General Formula = RCOHH• Contains a carbonyl group & a hydroxyl

group bonded to same C.• The H is acidic. It ionizes in water! • Carboxylic Acids are electrolytes!Carboxylic Acids are electrolytes!

=

O Acidic H+

Ionization of Acetic Acid

CH3COOH + H2O CH3COO- + H3O+

Table R

• General Format: R-C-OH or R-COOHO=

Which of the following is an electrolyte?A. CH3OH

B. CH3COOH

C. CH2O

D. C3H6O

Correct answer is B, the carboxylic acid.

alcohol

aldehyde

ketone

Which of the following is a nonelectrolyte?

A. HClB. CH3COOH

C. NaOHD. CH3OH

Correct answer is D, an alcohol.

Naming Carboxylic Acids

• NeverNever need a number – functional group always at end.

• Find name of corresponding hydrocarbon.• Drop final –e. • Add the ending –oic + the word acid.

HCOH=

O

1 C methane. Methanoic acid

Sting in red ants, bees

HHCCOH H

=

OEthanoic AcidorAcetic acid

2 C ethane

CH3CH2CH2CH2COOH

5 C’s pentane so the name is pentanoic acid.

Common carboxylic acids

• Acetic acid – vinegar. Also produced in doughs leavened with a specific yeast sourdough bread

• Citric acid• Tannic acid• Ascorbic acid• Lactic acid

– Poly(lactic acid) – biodegradable polymers used as sutures in internal surgery.

Properties of Carboxylic Acids

• Contain –COOH group.

• H is bonded to O. Hydrogen bonding occurs. Leads to increases in boiling point over corresponding alkane.

• Also can form hydrogen bonds with water so the smaller acids are pretty soluble.

Esters

• General format: RCOR‘

• R and R‘ = hydrocarbon branches. Can be the same or different.

• Esters contain a carbonyl group and a bridge O, both in the middle of the chain.

• Esters are POLAR, but NO H bonded to O however.

=

O

Esters• RCOR‘ or RCOOR’

• Combination of a carboxylic acidcarboxylic acid & an alcoholalcohol.

• The carbonyl group and “R” come from the carboxylic acid.

• The bridging O and the R’ come from the alcohol.

=O

Esters

• Responsible for many distinctive odors

• Pineapple• Banana• Orange• Apple• Wintergreen

Naming Esters

• Name the hydrocarbon branch bonded to the bridge O first. Branches end in –yl.

• The base name is derived from the branch containing the carbonyl group. Count up all the C atoms in this branch, including the C in the carbonyl.

• Find the hydrocarbon base name. Drop the final –e and add –oate.

CH3CH2COCH3

=

O

Carbonyl Group

Bridge O

So you name this branch 1st.

Methyl Propanoate

CH3CH2CH2COCH2CH3

=

O

Name this branch 1st.

Ethyl Butanoate

Pineapple

Bridge O

CH3COCH2CH2CH2CH2CH3=

O Bridge O

Name this branch 1st.

Pentyl Ethanoate

Banana

CH3OCCH2CH2CH3

=

O

Bridge O

Name this branch 1st.

4 C’s on the other side = but

Methyl butanoate - apple

CH3CH2CH2CH2CH2CH2CH2CH2-O-C-CH3

O=Bridge O

Name this branch 1st.

2 C’s on the other side: ethane

Octyl Ethanoate orange