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Chemistry > 17.3 > Flashcards

17.3 Flashcards

1
Q

what is the group for carboxylic acids

A

COOH

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2
Q

name the compound CH3CH2COOH

A

propanoic acid

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3
Q

name the compound HOOCCOOH

A

ethanedioic acid

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4
Q

what is the structure of formic acid

A

HCOOH

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5
Q

what is the structure of acetic acid

A

CH3COOH

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6
Q

what is the structure of oxalic acid

A

HOOCCOOH

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7
Q

what is the structure of benzoic acid

A

C6H5COOH

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8
Q

how many polar bonds are there in a carboxylic acid

A

3 (all of them)

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9
Q

what forms a carboxylate ion (COO-)

A

loss of a hydrogen from a carboxylic acid

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10
Q

what are the physical characteristics of carboxylic acids

A

distinctive smells and sour tastes

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11
Q

explain why carboxylic acids have high melting and boiling points

A

the 3 polar bonds mean that they have strong intermolecular forces (hydrogen bonding) which require large amounts of energy to overcome

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12
Q

what is the trend in melting and boiling points as chain length of carboxylic acids increases

A

melting and boiling points increase as chain length increases because London forces between non-polar hydrocarbon chains increase which require more energy to overcome

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13
Q

how do dimers form in carboxylic acids

A

in the absence of water hydrogen bonds form between carboxylic acid groups on shorter chain carboxylic acids

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14
Q

what is the trend between solubility and chain length of carboxylic acids and why

A

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

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15
Q

what is formed when carboxylic acids are reduced

A

primary alcohols

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16
Q

what is formed when carboxylic acids in a neutralization reaction

A

carboxylate salt

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17
Q

what is formed when carboxylic acids in a halogenation reaction

A

acyl chloride

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18
Q

what is formed when carboxylic acids in an esterification reactions

A

ester

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19
Q

how are carboxylic acids formed from oxidation

A

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

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20
Q

what does [O] represent in an equation for the formation of a carboxylic acid

A

the oxygen supplied by acidified potassium dichromate (VI)

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21
Q

how are carboxylic acids formed from hydrolysis

A

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

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22
Q

what occurs in the acidic hydrolysis of nitriles

A

heated under reflux with a dilute acid producing a carboxylic acid and ammonium _______ (e.g. HCl acid gives ammonium chloride)

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23
Q

what occurs in the alkaline hydrolysis of nitriles and how can you produce a carboxylic acid from this reaction

A

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

24
Q

why can carboxylic acids not be reduced to aldehydes

A

because aldehydes are more easily reduced than carboxylic acids so any aldehyde produced will be immediately reduced to a primary alcohol

25
Q

what are the conditions and reducing agent for the reduction of carboxylic acids

A

lithium tertahydridoaluminate in a solvent of dry ether

26
Q

what is used in neutralizing carboxylic acids

A

aqueous alkali

27
Q

what is the reagent and conditions for the halogenation of carboxylic acids

A

phosphorus(V) chloride in anhydrous conditions

28
Q

why must anhydrous conditions be used for the halogenation of carboxylic acids

A

because the acyl chloride product and reagent (phosphorus(V) chloride) react with water

29
Q

what is produced and what can be observed in the halogenation of carboxylic acids

A

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

30
Q

what are the uses of esters in industry

A

solvents
polymers (polyesters)

31
Q

what are the reagents for the esterification of carboxylic acids

A

alcohol and an acid catalyst (concentrated sulfuric acid)

32
Q

what is the general formula for acyl chlorides

A

RCOCl

33
Q

how are acyl chlorides produced form carboxylic acids

A

the OH group in COOH is replaced by Cl

34
Q

how does the structure of acyl chlorides effect how it reacts

A

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)

35
Q

how do acyl chlorides react with water

A

react vigorously with cold water producing a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off

36
Q

how do acyl chlorides react with alcohols

A

react readily and produce a carboxylic acid and hydrogen chloride gas which can be seen as misty fumes given off

37
Q

what is the first stage of the reaction between acyl chloride and concentrated ammonia solution

A

an amide and hydrogen chloride gas is produced which can be seen as misty fumes given off

38
Q

what is the second stage of the reaction between acyl chloride and concentrated ammonia solution

A

the amide acts as a base and hydrogen chloride is an acidic gas therefor they react together to produce ammonium chloride

39
Q

what is the general formula for primary amines

A

RNH2

40
Q

what is formed in the reaction between a primary amine and acyl chloride

A

N-substituted amide

41
Q

what does N-substituted amide mean in a molecule

A

shows that there is a alkyl group attached to the N not the C

42
Q

what is the general formula for secondary amines

A

R2NH

43
Q

what is formed in the reaction between a secondary amine and acyl chloride

A

two substituted amide
N-N-dimethylethanamide

44
Q

what is the general formula for tertiary amines

A

R3N

45
Q

why do acyl chlorides not react with tertiary amines

A

because there is no H atom to react with Cl to form hydrogen chloride

46
Q

what are the physical properties of esters

A

colourless liquids
low mp & bp
insoluble in water

47
Q

why are esters insoluble

A

all of the hydrogen atoms are attached to carbon atoms therefor hydrogen bonding cannot occur

48
Q

what are esters often used in

A

perfumes
food flavorings
solvents
anesthetic
biofuels

49
Q

define hydrolysis

A

the breaking of a compound by water

50
Q

describe the hydrolysis of esters in acidic conditions

A

warm with water and sulfuric acid (acts as a catalyst) to form a carboxylic acid and an alcohol

51
Q

describe the hydrolysis of esters in alkaline solution

A

heated under reflux with sodium hydroxide to form a carboxylate salt and an alcohol

52
Q

how can a carboxylate salt produced from the alkaline hydrolysis of esters be converted to a carboxylic acid

A

add dilute acid

53
Q

define condensation polymerisation

A

the formation of a polymer by the reaction of two different monomers in which a small molecule is also formed (usually water)

54
Q

what is the difference between addition and condensation polymerisation

A

condensation polymerisation involves 2 different monomers and a small molecule is produced (usually water)

55
Q

what is a diol

A

molecule has a hydroxyl group on each end

Chemistry (46 decks)

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