ACT 12 - CARBOXYLIC ACID Flashcards
⮚ occupy a central place among carbonyl compounds
⮚ Not only are they valuable in themselves, they also serve as starting materials for preparing numerous carboxylic acid derivatives such as acid chlorides, esters, amides, and thioesters.
⮚ Present in the majority of biological pathways, in many industrial processes and most biological pathways
⮚ the starting materials from which other acyl derivatives are made
Carboxylic acid has a carbonyl group (C=O) with a hydroxyl group (—OH) bonded to the carbonyl carbon atom. The functional group is represented in three ways.
carboxylic acids
Carboxylic acids are found in nature:
❑ _______, CH3COOH: chief organic component of vinegar
❑______, CH3CH2CH2COOH: rancid odor of sour butter
❑ ______: CH3(CH2)4CO2H: distinct smell of goats and dirty gym socks (the name comes from the Latin caper, meaning “goat”)
❑ ______: a major component of human bile
❑ long-chain aliphatic acids such as _________, CH3(CH2)14COOH, a biological precursor of fats and vegetable oils and other fatty acids in the body
- acetic acid
- butanoic acid
- hexanoic acid (caproicacid)
- cholic acid
- palmitic acid
I. Physical Properties
- Like alcohols, carboxylic acids are:
strongly associated because of hydrogen bonding.
This strong hydrogen-bonding has a noticeable effect on boiling points, making carboxylic acids much ______ boiling than the corresponding alcohols.
- As to solubility with water:
carboxylic acids containing up to 4 carbon atoms are _____ in water because they form H-bond with water.
The solubility _____ with increase in the number of carbon atoms as the larger hydrocarbon part resists the formation of H-bonds.
- higher
- miscible
- decreases
(+) #C
(-) solubility
❑ Carboxylic acids with more than 6 carbons are only ______ soluble in water, but the alkali metal salts of carboxylic acids are often _____ water-soluble.
❑ __________ is nearly insoluble in cold water because of the larger hydrocarbon part.
❑ Carboxylic acids are ______ in less polar organic solvents such as benzene, ether, alcohols etc.
- slightly
- highly
- Benzoic acid
- soluble in less polar organic solvents (benzene, ether, alcohols)
❑ CA ________ carbon atoms are colorless liquids with unpleasant odor.
❑ CA containing ________ carbon atoms are colorless waxy solids and are odorless due to their low volatility
❑ __________ & _________ are odorless solids.
- up to 9
- more than 9
- Aromatic carboxylic acids & dicarboxylic acids
Chemical Properties
- Release of ___________:
⮚ the most obvious property of carboxylic acids is implied by their name: carboxylic acids are acidic.
⮚ React with bases such as ______ & ______ to give _______________
COOH + NaOH, H2O —> RCOO Na+ +H2O
- Hydrogen Ion
- NaOH and NaHCO3
- metal carboxylate salts
- Reaction with metals: also known as _________
⮚react with active metals such as __________ to form their respective salts. In the process they liberate H2 gas.
- Reaction with ALKALIES: also known as __________
⮚ react with strong ______ to produce _____ and ____________ (an ionic compound in which the negative ion is a carboxylate ion)
- Ionization
- Na
- K
- Ca
- Mg
- Neutralization
- bases
- water and a carboxylic
acid salt
- Reaction with Carbonates and Bicarbonates:
- Carboxylic acids decompose carbonate and bicarbonate producing _______
- CO2 gas
- __________________:
- When acids are warmed with alcohols in the presence of conc. H2SO4 (or dry HCl), pleasant fruity smelling esters are formed.
- In this reaction, conc. H2SO4 acts as ______________
💡Application:
- _________ of salicylic acid with methanol results to ____________ or ____________
- Fischer Esterification
- dehydrating agent/acid catalyst
- esterification
- methyl salicylate or oil of wintergreen
alcohol + carboxylic acid <—-> ester + H2O, salicylic acid + CH3OH (H+) —> methyl salicylate + H2O
IV. Pharmaceutic Uses
__________:
❑ Aka: ethanoic acid, ________, ______, ______
❑ manufacture of vitamins, antibiotics, hormones and other products
Acetic Acid
- ethylic acid, vinegar acid, and methane carboxylic acid
___________:
⮚antimicrobial preservative, antifungal, and tablet and capsule lubricant
⮚used in combination with salicylic acid, as in Whitfield’s ointment, for use as an antifungal for athlete’s foot and ringworm
Benzoic Acid
__________:
⮚ treat many skin disorders: acne, dandruff, psoriasis, seborrheic dermatitis of the skin and scalp, calluses, corns, common warts, and plantar warts
⮚ depending on the dosage form and strength of the preparation
Salicylic Acid
