Download Chemistry Project on Carboxyl Acids

Class: 5E
Group members: Wong Ka Chun (42)
Lau Yuk To (32)
Chemistry Project on Carboxyl Acids
Lam Man Chung(29)
Chan Ming Hung(26)
Alkanoic acid
There is a class of carbon compounds that contain the carboxyl group called carboxylic acids.
Carboxylic acids are organic acids. If carboxylic acids contain one carboxyl group, they are
named as alkanoic acids. The general formula for alkanoic acids is CnH2n+1COOH, where n
can be 0, 1, 2, 3, etc.
All
alkanoic acids are named by replacing the last letter ‘‘e’’ in the names of the parent
hydrocarbons by a suffix ‘‘-oic acid’’. As the carboxyl group must exist at the end of the
parent chain, there is no need to indicate its position.
Structure of a carboxylic acid, functional group is COOH
Alkanoic Acids with not more than 8 carbon atoms
IUPAC name
Methanoic acid
Condensed Structural formula
Structural formula
HCOOH
Ethanoic acid
CH3COOH
Propanoic acid
CH3CH2COOH
Butanoic acid
CH3CH2CH2COOH
Pentanoic acid
CH3CH2CH2CH2COOH
Hexanoic acid
Heptanoic acid
CH3CH2CH2CH2CH2COOH
CH3CH2CH2CH2CH2CH2COOH
1 Octanoic acid
CH3CH2CH2CH2CH2CH2CH2COOH
Other examples of carboxylic acids:
#4-methylhexanoic acid
#Ethanedioic acid (Oxalic acid)
Physical Properties of Carboxylic Acids
*Solubility*
Carboxylic acids are polar. As they are both hydrogen-bond acceptors (the carbonyl)
and hydrogen-bond donors (the hydroxyl), they also participate in hydrogen bonding.
Smaller carboxylic acids (1 to 5 carbons) are soluble with water, whereas higher
carboxylic acids are less soluble due to the increasing hydrophobic nature of the alkyl
chain. These longer chain acids tend to be rather soluble in less-polar solvents such as
alcohols.
*Boiling Points*
They have higher boiling points than water due to their large surface areas.
*Acidity*
Carboxylic acids are typically weak acids, meaning that they only partially dissociate
into H+ cations and RCOO– anions in neutral aqueous solution.
*Odour*
Carboxylic acids often have strong odours, especially the volatile derivatives. On
the other hand, esters of carboxylic acids tend to have pleasant odours and many are
used in perfumes.
* Occurrence*
Many carboxylic acids are produced industrially on a large scale. They are also
pervasive in nature. Esters of fatty acids are the main components of lipids and
polyamides of aminocarboxylic acids are the main components of proteins.
Typical Reactions of Carboxylic Acids
1. Esterification*
2 2.Reduction*
3.Amide formation*
Step1:
Step2:
*Observations
1. For the esterification, esters will flow on the water surface due to they
are immiscible with water. A sweet fruity smell gives out.
2. After reduction, there is no observable change for the reactions.
3. When ammonium carboxylates are heated in the process 2 of amide
formation, dehydration takes place and white solid amides are formed.
3 Uses of the Carboxylic Acids
Carboxylic acids are useful in our daily life and industrial use. Also, the acids
can be used in the laboratory for the reactions in organic chemistry. The applications
of the acids which have been mentioned in the table of pages 1 and 2 will further
introduce below.
-Methanoic acid: In synthetic organic chemistry, this acid is often used as a
source of hydride ion, i.e. laboratory use.
-Ethanoic acid: #Ester production
H3C-COOH + HO-R
(R = a general alkyl group)
→
H3C-CO-O-R
+
H2O
#Acetic anhydride
CH3CO2H → CH2=C=O + H2O
CH3CO2H + CH2=C=O → (CH3CO)2O
#Vinegar
Vinegar is typically 4-18% acetic acid by mass
#Use as solvent
Glacial acetic acid is an excellent polar protic solvent
-Propanoic acid: #Preservative for stored grains
-Butanoic acid:
#Used in the preparation of various butyrate esters.
-Petanoic acid: #Can be found in flowering plant valerian, valerian
is a kind of herbal which can be medical use.
-Hexanoic acid: #One of the chemicals that give the decomposing fleshy
seed coat
-Heptanoic acid: #Used in the preparation of esters, such as ethyl
heptanoate, which are used in fragrances and as
artificial flavors.
4 #One of many additives in cigarettes
-Octanoic acid: #Used commercially in the production of esters used in
perfumery and also in the manufacture of dyes.
#Used as a food contact surface sanitizer in commercial
food handling establishments on food processing
equipment
#Used as disinfectant in health care facilities
#Used as an algaeci
#The octanoic acid breath test is used to measure gastric
emptying.
- Ethanedioic acid: # Commonly used for bleaching and clearing of the
metal surface and textile #A common reluctant for redox titration.
‐*Hydroxybutanedioic:#Additive of food product
#Medical
Hydroxybutanedioic can help human body to absorb amino
acids, so that it will add to some medicine.
#Skin care Mild hydroxybutanedioic can help skin metabolism
*Note:
Hydroxybutanedioic (Malic acid) can be found in apples, grapes, hawthorn.
Structural formula of hydroxybutanedioic
~THE END~
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