Ch. 23 Functional Groups - PowerPoint Presentation

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Ch. 23 Functional Groups

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Functional GroupAn atom, group of atoms or type of bond in an organic molecule that react in a predictable manner

Symbol

“

R

”

is used to represent the hydrocarbon fragment of the organic molecule

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Alkyl Halides

R-X

Organic compounds containing halogens

X = F, Cl, I or Br

Prefixes are:

F=

fluoro

, Cl=

chloro

, Br=

bromo

, I=

iodo

Halocarbons in which a halogen is attached to a carbon of an

arene

ring are called

aryl halides

.

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Naming Alkyl Halides

Name Parent Chain

Number parent chain

Name the branches

Name the compound

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Naming Alkyl Halides

Name Parent Chain

Number parent chain

Name the branches

Name the compound

2

-bromo, 4-chloropentane

1-chlorobenzene

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Alcohols

R- OH

Organic compounds containing a

hydroxyl (-OH) group

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Naming Alcohols

The parent chain must contain the atom attached to the –OH group.

The parent chain ends with

“-

ol

”

instead of

“-e”

Number the carbon atoms in the parent chain so that the –OH group is given the lowest number

Name and identify positions of the branches

Name the compound

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1-Ethanol

3-methyl-1-butanol

2-propanol

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Alcohols

Alcohols can have more than one hydroxyl group.

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Alcohols

Primary Alcohols:

hydroxyl group is attached to an end carbon

CH

3

-

CH2

- CH2 - OH Propanol

Secondary Alcohol:

Hydroxyl group is attached to a carbon atom that is attached to 2 other carbons

CH

3

-CH- CH3 2-Propanol

OH

Tertiary alcohol:

hydroxyl is attached to a carbon that is attached to 3 other carbons

CH

3

CH

3

-CH- CH

3

2- methyl - 2-Propanol

OH

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Fermentation

Fermentation

is the production of ethanol from sugars by the action of yeast or bacteria. A second reaction product, carbon dioxide, causes bread to rise

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Reactions with Alcohols

Addition reactions of alkenes are an important method of introducing new functional groups into organic molecules.

In an

addition reaction

, a substance is added at the double or triple bond of an alkene or alkyne.

Double and triple bonds between carbon atoms are much more reactive than single bonds between carbon atoms.

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The addition of water to an alkene is a

hydration reaction.

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Ethers

R—O—R

An

ether

is a compound in which oxygen is bonded to two carbon groups

Ether

oxygens are NOT generally part of the main chain in linear ethers.

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Naming Ethers (Common)

The alkyl groups attached to the ether linkage are named in alphabetical order and are followed by the word

ether

.

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IUPAC Naming Ethers

The

larger of the two alkyl groups attached to the oxygen is considered to be the parent

compound

The smaller alkyl group and the oxygen atom are considered to be a substituent group on the parent

compound with –oxy suffix

Cyclic

ethers are named as

oxacycloalkanes

with the oxygen being at position 1 of the chain.

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Carbonyl Groups A

functional group with the general structure C

═

O

.

The C

═

O functional group is present in aldehydes and ketones.

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Aldehydes

An

aldehyde

is an organic

compound containing an oxygen at the END of a parent chain and double bonded to a carbon that is attached to at least one hydrogen.

Naming Aldehydes:

The

longest

continuous chain containing the aldehyde group is considered to be the parent compound.The

carbonyl carbon is part of the parent chain and is always considered to be in the #1 position.

The

suffix “al” is added to the name of the parent compound to indicate that the compound is

an aldehyde

.

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Naming Aldehydes

1-ethanal

2-chloro-1-pentanal

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Ketone

A

ketone

is an organic compound in which the carbon of the carbonyl group is joined to two other

carbons (found in the middle of a parent chain).

Naming Ketones:

The longest continuous chain containing the ketone group is considered to be the parent compound

.

A number is included before the name of the parent compound to indicate the position of the ketone group. The chain is always numbered so that the carbonyl carbon has the lowest possible number.

The suffix “one” is added to the name of the parent compound to indicate that the compound is a ketone.

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Naming Ketones

2-pentanone

3-methyl-2-butanone

2,3-hexandione

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Properties of Aldehydes and ketones

Many aldehydes and ketones have distinctive odors.

Aromatic aldehydes are often used as flavoring agents.

Benzaldehyde is known as oil of bitter almond.

Cinnamaldehyde

is the source of the odor of oil of cinnamon.

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Carboxyl Groups

Carboxyl groups consist of a carbonyl group (

C

═

O)

attached to a hydroxyl group (-OH)

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Carboxylic Acids

A

carboxylic

acid is a compound with a carboxyl group

The general formula for a carboxylic acid is

RCOOH

Contains a carbonyl (C=O) and a hydroxyl (-OH)

Carboxylic

acids give a variety of foods a distinctive sour taste

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Naming Carboxylic Acids

The

longest continuous chain containing the carboxyl group is considered to be the

parent compound

.

The

carboxyl carbon is part of the parent chain and is always considered to be in the #1 position.

The

suffix “

oic” is added to the name of the parent compound, and the word “acid” is added to the name.

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Properties of Carboxylic AcidsPungent odors, but odor decreases as number of C-atoms increases

Carboxyl group is often found in fatty acids, that are natural occurring in fats and oils

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Ethanoic Acid

– Acetic Acid – Vinegar

Methanoic

Acid-

Formic Acid – Irritant found in the ant and bee stings

Octadecanoic

Acid

– Stearic Acid – fatty acid found in animal fats used in making soaps & candles

Butanoic

Acid

– Butyric Acid – found in butter, used in plastic manufacturing

Ethanedioic

Acid

– Oxalic Acid – found in plants, used in wood bleaching

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Esters

Esters contain a carbonyl group and an ether link to the carbonyl carbon

General formula for a ester is RCOOR

Derivatives of carboxylic acids in which the –OH of the carboxyl group has been replaced by an –OR from an alcohol

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Naming Esters

Determine

the name of the “R”

group (alcohol).

Place

the name of the “R” group in front of the name of the parent

acid,

forming two words

. Change the ending to -

ylDetermine the name of the parent acid, and change its suffix from “—i

c

” to “—ate.” Drop the

word “acid

.”

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Preparation of Esters

Esters may be prepared from a carboxylic acid and an alcohol.

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Properties of Esters

Many are used in artificial flavorings, fragrances, and perfumes

Many esters smell fruity

Many are volatile

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Amine

Organic compounds related to ammonia (NH

3

)

Three kinds:

Primary

– one hydrogen in ammonia has been replaced with a alkyl group

Secondary

- two hydrogen atoms in ammonia have been replaced by two alkyl groups

Tertiary – all three hydrogen atoms in ammonia have been replaced by three alkyl groups

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Amines

Primary amines are named by treating the –NH

2

(amino) group as a substituent group on the longest (parent) chain

Number the chain so you have the lowest values

Indicate the number the amino group is on

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Amines

Secondary and tertiary amines are named according to a “common” naming system

When naming secondary and tertiary amines, name the branches off of the nitrogen in alphabetical order. Use prefixes if more than one of the same branch.

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Amides

A carboxyl group that has -NH

2

replacing the -OH

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Amides

Naming Amides

Identify the carboxylic acid from which the amide was derived and change the suffix from “-

oic

” to “amide” and drop the word acid

Add the names of any branch chains