17.3 Flashcards
what is the group for carboxylic acids
COOH
name the compound CH3CH2COOH
propanoic acid
name the compound HOOCCOOH
ethanedioic acid
what is the structure of formic acid
HCOOH
what is the structure of acetic acid
CH3COOH
what is the structure of oxalic acid
HOOCCOOH
what is the structure of benzoic acid
C6H5COOH
how many polar bonds are there in a carboxylic acid
3 (all of them)
what forms a carboxylate ion (COO-)
loss of a hydrogen from a carboxylic acid
what are the physical characteristics of carboxylic acids
distinctive smells and sour tastes
explain why carboxylic acids have high melting and boiling points
the 3 polar bonds mean that they have strong intermolecular forces (hydrogen bonding) which require large amounts of energy to overcome
what is the trend in melting and boiling points as chain length of carboxylic acids increases
melting and boiling points increase as chain length increases because London forces between non-polar hydrocarbon chains increase which require more energy to overcome
how do dimers form in carboxylic acids
in the absence of water hydrogen bonds form between carboxylic acid groups on shorter chain carboxylic acids
what is the trend between solubility and chain length of carboxylic acids and why
solubility decreases as chain length increases because shorter chain carboxylic acids can form hydrogen bonds with water molecules whereas longer chain carboxylic acids can’t
what is formed when carboxylic acids are reduced
primary alcohols
what is formed when carboxylic acids in a neutralization reaction
carboxylate salt
what is formed when carboxylic acids in a halogenation reaction
acyl chloride
what is formed when carboxylic acids in an esterification reactions
ester
how are carboxylic acids formed from oxidation
oxidation of primary alcohols or aldehydes using acidified potassium dichromate (VI) and heated under reflux
then fractionally distil the product to obtain a pure sample
what does [O] represent in an equation for the formation of a carboxylic acid
the oxygen supplied by acidified potassium dichromate (VI)
how are carboxylic acids formed from hydrolysis
nitriles under go hydrolysis under reflux with dilute acid or aqueous alkali which breaks the CN triple bond and produces a carboxylic acid and ammonia or an ammonium ion
what occurs in the acidic hydrolysis of nitriles
heated under reflux with a dilute acid producing a carboxylic acid and ammonium _______ (e.g. HCl acid gives ammonium chloride)
what occurs in the alkaline hydrolysis of nitriles and how can you produce a carboxylic acid from this reaction
heated under reflux with sodium hydroxide solution sodium salt and ammonia gas are produced
the products must then be acidified with a strong acid to create a carboxylic acid
why can carboxylic acids not be reduced to aldehydes
because aldehydes are more easily reduced than carboxylic acids so any aldehyde produced will be immediately reduced to a primary alcohol
what are the conditions and reducing agent for the reduction of carboxylic acids
lithium tertahydridoaluminate in a solvent of dry ether
what is used in neutralizing carboxylic acids
aqueous alkali
what is the reagent and conditions for the halogenation of carboxylic acids
phosphorus(V) chloride in anhydrous conditions
why must anhydrous conditions be used for the halogenation of carboxylic acids
because the acyl chloride product and reagent (phosphorus(V) chloride) react with water
what is produced and what can be observed in the halogenation of carboxylic acids
phosphorus trichloride oxide and acyl chloride is in solution and must be fractionally distilled to get pure products
misty fumes produced from hydrogen chloride gas given off
what are the uses of esters in industry
solvents
polymers (polyesters)
what are the reagents for the esterification of carboxylic acids
alcohol and an acid catalyst (concentrated sulfuric acid)
what is the general formula for acyl chlorides
RCOCl
how are acyl chlorides produced form carboxylic acids
the OH group in COOH is replaced by Cl
how does the structure of acyl chlorides effect how it reacts
the central carbon atom is attached to 2 electronegative atoms so it becomes electron deficient (&+) therefor it will readily react with nucleophiles (often molecules containing an O or N)
how do acyl chlorides react with water
react vigorously with cold water producing a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off
how do acyl chlorides react with alcohols
react readily and produce a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off
what is the first stage of the reaction between acyl chloride and concentrated ammonia solution
an amide and hydrogen chloride gas is produced which can be seen as misty fumes given off
what is the second stage of the reaction between acyl chloride and concentrated ammonia solution
the amide acts as a base and hydrogen chloride is an acidic gas therefor they react together to produce ammonium chloride
what is the general formula for primary amines
RNH2
what is formed in the reaction between a primary amine and acyl chloride
N-substituted amide
what does N-substituted amide mean in a molecule
shows that there is a alkyl group attached to the N not the C
what is the general formula for secondary amines
R2NH
what is formed in the reaction between a secondary amine and acyl chloride
two substituted amide
N-N-dimethylethanamide
what is the general formula for tertiary amines
R3N
why do acyl chlorides not react with tertiary amines
because there is no H atom to react with Cl to form hydrogen chloride
what are the physical properties of esters
colourless liquids
low mp & bp
insoluble in water
why are esters insoluble
all of the hydrogen atoms are attached to carbon atoms therefor hydrogen bonding cannot occur
what are esters often used in
perfumes
food flavorings
solvents
anesthetic
biofuels
define hydrolysis
the breaking of a compound by water
describe the hydrolysis of esters in acidic conditions
warm with water and sulfuric acid (acts as a catalyst) to form a carboxylic acid and an alcohol
describe the hydrolysis of esters in alkaline solution
heated under reflux with sodium hydroxide to form a carboxylate salt and an alcohol
how can a carboxylate salt produced from the alkaline hydrolysis of esters be converted to a carboxylic acid
add dilute acid
define condensation polymerisation
the formation of a polymer by the reaction of two different monomers in which a small molecule is also formed (usually water)
what is the difference between addition and condensation polymerisation
condensation polymerisation involves 2 different monomers and a small molecule is produced (usually water)
what is a diol
molecule has a hydroxyl group on each end