CARBOXYLIC ACIDS AND ACID DERIVATIVES
I. OBJECTIVES
1. To be able to prepare an organic acid in form of acetic acid.
2. To be able to prepare and describe the reactions of some acid derivatives.
II. INTRODUCTION
Carboxylic acid, any of a class of organic compounds in which a carbon (C) atom is bonded to
an oxygen (O) atom by a double bond and to a hydroxyl group (―OH) by a single bond. A fourth bond links the
carbon atom to a hydrogen (H) atom or to some other univalent combining group. The carboxyl (COOH) group
is so-named because of the carbonyl group (C=O) and hydroxyl group.
The different acid derivatives are acid halides, acid anhydrides, esters and amides. Acid halides s a
chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group. If the acid is a
carboxylic acid, the compound contains a –COX functional group, which consists of a carbonyl group singly
bonded to a halogen atom. Acid anhydrides is a type of chemical compound derived by the removal of water
molecules from an acid. In organic chemistry, organic acid anhydrides contain the functional group
R(CO)O(CO)R'.
Esters is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH
(hydroxyl) group is replaced by an –O–alkyl (alkoxy) group. Usually, esters are derived from substitution
reaction of a carboxylic acid and an alcohol. Amide also known as an organic amide or a carboxamide, is a
compound with the general formula RC(=O)NR′R″, where R, R', and R″ represent organic groups or hydrogen
atoms.
III. RESULTS AND DISCUSSION
A. Preparation of Glacial Acetic Acid
1. Explain why concentrated acetic acid is called “glacial” acetic acid?
Acetic acid is sometimes called glacial acetic acid because it solidifies just below room
temperature, at 16.7°C. Acetic acid can be concentrated by dripping the impure compound over a
"stalactite" of glacial (frozen) acetic acid.
B. Derivatives of Acids
1. Preparation of Ethyl Acetate
Write a chemical equation in the reaction involved: CH3COOH+C2H5OH=CH3COOC2H5 +H2O
Observation: After the acetic acid, ethyl alcohol and ester sulfuric acid (H2SO4 ) place at the
beaker containing water and heat it became a colorless liquid has a sweet, fruity odor.
2. Esterification
Write a chemical equation in the reaction involved: CH3COCl+C2H5OH=CH3COOC2H5+HCl
Observation: After the ethanol and acetyl chloride’s reaction is complete, and neutralize the
solution with dilute sodium Hydroxide the odor generally has a sweet smell. The red litmus paper
became red and the blue became blue which is base.
C. Reaction of the Acid Derivatives
1. Acetic Anhydride
Write a chemical equation in the reaction involved: (CH3CO)2O + H2O → 2 CH3CO2H.
Observation: acetic anhydride added in 5ml of water after heating the tube litmus red paper turns
blue which means that the solution is acidic.
2. Acetamide
Write a chemical equation in the reaction involved: C2H5NO+NaOH=C2H5ONa
Observation: Red litmus paper turned blue which is basic. Ammonia gas is given off and left with
a solution containing sodium ethanoate. Ammonia evolved.
Conclusion:
In conclusion, the structure of the compounds plays an important role in its solubility. Carboxylic acids
are usually resistant to oxidization but there are some cases that they can be oxidize. Litmus is a weakly
acidic, colored organic dye. As its environment changes from acid the molecule changes from the protonated
acid to the ionized salt. Its color also changes from red to blue. Because of this, litmus paper is widely used
to distinguish between acids and bases.
References:
https://antoine.frostburg.edu/chem/senese/101/organic/faq/ethanoic-acid.shtml
https://en.wikipedia.org/wiki/Amide
https://en.wikipedia.org/wiki/Ester
https://en.wikipedia.org/wiki/Acid_anhydride
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Acid
_Halides