Carboxylic Acids. A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a...
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Transcript of Carboxylic Acids. A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a...
A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group.
carbonyl
group
O
CH3 — C—OH hydroxyl group or CH3COOH
carboxyl group
Carboxylic Acids
CH3CO2H
• The common names use prefixes “form-” and “acet-” for the first
two carboxylic acids.
H-COOH methanoic acid formic acid
CH3-COOH ethanoic acid acetic
acid
CH3-CH2-COOH propanoic acid
CH3-CH2-CH2-COOH butanoic acid
Naming Carboxylic Acids
Naming Carboxylic Acids– Identify the root. Name the parent alkane. Drop the –e on the parent
alkane to get the root.– Identify the suffix. For carboxylic acid, the suffix is –oic acid. No
numbers in the suffix because the carboxyl group is always carbon 1.– Identify the prefix. Name and number any alkyl side groups on the
main chain. – Name the compound. Combine the prefix, root, and suffix
13
3-Methylbutanoic acid
OH
OOH15
5-Hydroxylhexanoic acid
CH3─CH2─CH─COOH
CH2 – CH3
2-Ethylbutanoic acid
2CH3─CH─CH2─COOH
CH3 1
Physical properties of Carboxylic Acids
1- The carboxyl group contains three polar covalent bonds;
C=O, C-O, and O-H. So they are so polar.
2- Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding.
3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding.
4- Liquid carboxylic acids have sharp and disagreeable odors.
5- They taste sour (exist in pickle, lime, and lemon).
H3C C
O
O
H
CH3C O
O
H- +
+ -
Hydrogen bondingbetween two molecules
Formation of Esters
RC O HO
A carboxylic acid
=
Fischer Esterification
RCOR'O
RC-OHO
H- O R '
==
An alcoholA carboxylic acid An ester
H2SO4
+ H2O
Naming Esters
1. Identify the root. Identify part of ester that contains carbonly group (from acid). Name the parent carboxylic acid. Drop the suffix of the of the acid to form the root
2. Identify the suffix. The suffix for an ester is –oate
3. Consider the part of the ester that is associated with the alcohol. Name only the alkyl group.
4. Name the compound. Combine the prefix, root and suffix.
propyl
CH3 — C—O —CH2—CH2—CH3
Propyl ethanoate (IUPAC)
CH3—CH2 —C—O—CH2—CH3
Ethyl propanoate
Naming of Esters
O
O
Name the following ester
• Parent carboxylic acid is
3-methylbutanoic acid
Root: 3-methylbutan
Suffix: -oat
Alcohol: ethanol
Prefix:ethyl
Name: ethyl 3-methylbutanoate
CH3
O
O
CH3
CH3
Esters give flowers and fruits their pleasant fragrances and flavors.
Properties of Esters
Hydrolysis: reaction with water.
(breaking a bond and adding the elements of water)
RCOR'O
RC-OHO
H- O R '
= =An alcoholA carboxylic acidAn ester
+ H2O +Heat
Acid
Chemical properties of Carboxylic Acids
3- Fischer Esterification:
- A carboxylic acid reacts with an alcohols to form an ester.
- Using an acid catalyst such as concentrated sulfuric acid.
CH3C-OHO
H-OCH2CH3
H2SO4CH3COCH2CH3
OH2O
Ethanoic acid(Acetic acid)
++
Ethyl ethanoate(Ethyl acetate)
Ethanol(Ethyl alcohol)
The best way to prepare an ester.