topic 17b: carbonyls
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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aldehyde
r-c=o-h
ketone
r-c=o-r’
naming aldehyde
• no need to include number • prefix-anal
naming ketone
-prefix-an-number-one
carbonyls IMFs
• LFs • permanent dipole due to delta positive C, delta negative O
compare a carbonyl to an alcohol with similar MR?
• same LF • alcohol has HYDROGEN BONDING
CARBONYLS H bonding with water
• delta negative O, lone pairs H bond with delta positive H on water
small carbonyls solubility
soluble in water due to H bonds; delta h in water attracted to lone pair on oxygen atom of carbonyl
LARGER carbonyls solubility
• less soluble • longer hydrocarbon chains which are hydrophobic and NON POLAR(can’t h bond w water) • proportion of molecule that can H bond w water smaller • strength of H bond with water weaker than IMFs between each molecule • so energetically unfavourable
aldehydes + acidified potassium dichromate (VI)
• OXIDATION • to form carboxylic acid • orange to green (cr2o7 2- to cr3+)
ketone + acidified potassium dichromate (vi)
NO CHANGE, stays orange - ketons are resistant to oxidation - no readily available h atom
tollens reagent is …
ammoniacal silver nitrate
tollens + aldehyde
• heat • oxidation of aldehyde • silver mirror formed
what is produced with tollens
• reduction of Ag+ to Ag • aledhyde oxidised to carboxylic acid
what is fehlings
• cu2+ in sodium hydroxide
what is benedicts
cu2+ in sodium carbonate
aldehyde + fehling/benedicts
HEAT - reduction. of cu2+ to cu+ -blue to brick red ppt - aldehyde oxidised to carboxylic acidf
aldehydes reduce to…
primary alcohol
ketones reduce to
secondary alcohol
reduction of carbonyl
• LiAlH4 in dry ether • EQN: + 2[H] • nucleophilic addition
carbonyl + HCN in the presence of KCN
• nucleophilic addition • c(OH)(CN)(R2)
carbonyl + 2,4 DNP
• orange ppt USEFUL AS COXYLIC ACIDS AND ESTER DONT GIVE POSITIVE
Iodoform test
• iodine + carbonyl + add sodium hydroxide until iodine decolourises • pale yellow PPT formed • ‘medical’ Smell
iodoform test product
CHI3