chapter 26 Flashcards
how do you make an aldehyde from a primary alcohol?
distillation
H+ /Cr2O7 2-
how do you make a ketone from a secondary alcohol?
reflux
H+ /Cr2O7 2-
what happens when you reflux a tertiary alcohol?
no reaction
what is the aldehyde functional group?
CHO
what is the ketone functional group?
CO
what happens when you oxidise aldehydes?
produces carboxylic acid
with H+ /Cr2O7 2-
why do carbonyls react with nucleophiles?
C=O bond is polar due to electronegativity difference
delta positive charge on carbon reacts with nucleophiles
aldehyde + 2[H]
alcohol
with NaBH4/H2O
ketone + 2[H]
alcohol
with NaBH4/H2O
what happens when carbonyls react with nucleophiles?
H- 2 electrons arrow to carbon atom
C=O bond to O atom
C=O has delta pos and neg charges
O- with two electrons arrow to H from water
H-O bond to O atom
produces alcohol + OH-
what happens to carbonyls when they are reacted with hydrogen cyanide (HCN)?
NC- triple bond arrow to carbon atom
C=O bond to oxygen atom
delta pos and neg charges on C=O
now single bond oxygen and extra carbon with triple bond to N
O- with two electrons arrow to H+
produces alcohol group
what happens when you add bradys’ reagent to aldehyde or ketone?
forms orange precipitate
dissolved in methanol and sulfuric acid
what happens when you add tollens’ reagent to aldehyde or ketone?
when added to aldehydes produces silver mirror
no reaction when added to ketones
Ag+ + e- –> Ag
what happens when compounds contain two carboxylic acid groups?
-dioic acid
what can carboxylic acids do with their O-H bond?
polar bond means it can hydrogen bond to themselves and water
as number of atoms in non-polar carbon chain increases, solubility increases
what are carboxylic acids are also classified as?
weak acids so partially dissociate when dissolved in water
what happens when carboxylic acids react with metals?
produces salt + H2
salt ends in -oate
redox reaction
what happens when carboxylic acids react with a base?
produces salt + water (neutralisation)
what are some examples of carboxylic acids reacting with a base?
ethanoic acid + CaO –> calcium ethanoate + water
methanoic acid + Na2CO3 –> sodium methanoate + CO2 + water
what are carboxylic acid derivatives?
compounds that can be hydrolysed to form the parent carboxylic acid
what are examples of carboxylic acid derivatives?
esters
acyl chloride
amide
acid anhydride
how do you name an acyl chloride?
named after parent carboxylic acid
e.g. ethanoyl chloride
how do you name an amide?
named after parent carboxylic acid
e.g. butanamide
what is a property of an acyl chloride?
very reactive so are easily converted back into carboxylic acids + derivatives
what happens when you add SOCl2 to a carboxylic acid?
acyl chloride + SO2 + HCl
what happens when acyl chlorides react with nucleophiles?
lose chloride ion
retains C=O double bond
(addition followed by elimination)
what happens when an acyl chloride reacts with water?
reacts violently to form carboxylic acid and hydrogen chloride gas
what can amines and ammonia do with acyl chlorides?
amines and ammonia can act as nucleophiles so react with acyl chloride
+ ammonia —> primary amide + NH4Cl
+ amide —> secondary amide + CH3NH3Cl
what happens when an acyl chloride reacts with an alcohol?
produces ester + HCl
how does an acid anhydride form?
by loss of water from two molecules of carboxylic acid
what happens when an acid anhydride reacts with a phenol?
phenyl ethanoate (ester) + ethanoic acid (carboxylic acid)
what is the functional group of esters?
-COO-
how do you name esters?
whats attached to the O atom is at the start e.g. methyl
then the rest of the chain is the end e.g. ethanoate
what happens when you react an alcohol and carboxylic acid?
produces ester + water
called esterification
what smell does esters have?
fruity smell
what does acyl chloride + alcohol make?
ester + HCl
what does acid anhydride + alcohol make?
ester + carboxylic acid
how come carboxylic acids don’t react with phenols to form esters?
carboxylic acids not reactive enough to produce esters with phenols
so must use acyl chlorides and acid anhydrides to form esters with phenols
what is ester hydrolysis?
esters react very slowly with water
what is reverse esterification?
ester is heated under reflux with dilute aqueous acid
ester + water –> carboxylic acid + alcohol
what is alkaline hydrolysis?
ester is heated under reflux with aqueous hydroxide ions to form carboxylate ion and alcohol
what is the test for a carboxyl group (carboxylic acid)?
add sodium carbonate
effervescence will occur
