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aldehyde Flashcards

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1
Q

what is the strcture of aldehyde

A

trigonal coplanar

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2
Q

carbonyl carbon is
and carbonyl oxygen is

A

electrophile (lewis acid)
nucleaophile (lewis base)

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3
Q

method suitable for volatile alcohol and is of industrial application

A

dehydrogentaion of alcohols

vapours of 1o and 2o are passed over heavy metal catalysts like CU/ Ag

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4
Q

ozonolysis of alkene

A

C=C +(i)O3 /(ii)Zn dust/ h20-> aldehyde or ketone

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5
Q

acids used in acid catalysed hydration af alkyne

A

hgso4 and h2so4

totomerise

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6
Q

rosenmund

A

chlorine chetayi mund PD H BARUNNU

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7
Q

CHROMYL CHLORIDE oxidation of methyl benzene

CrO2Cl2

A

AR-CHO

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8
Q

StepHen ReduCtioN

STANNOUS CHLORIDE

A

R-CN +SnCl2 +HCl-> RCH=NH(imine)
- H3O+ -> RCHO

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9
Q

eTard reaCtiO2n

cs2

A

toulene+ cro2cl2 in CS2-> chromium complex then acid hydrolysis-> AR-CHO

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10
Q

comercial preparation of BENZALDEHYDE

A

SIDE CHAIN CLORINATION + hydrolysis at 373K

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11
Q

subsituteted toulene is coverted to AR-CHO by

A

chromic oxide (cro3)
toulene + cro3+ acetic anhydride heatrtt-> benzylidene diacetate
acid hydrolysis + heeeat
AR-CHO

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12
Q

GATTERMAN KOCH

A

ben + CO. HCl / anh ALCl3 or cucl-> AR-CHO

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13
Q

prepare ketones from:
1. acyl chloride
2. nitrile
3. benzene

A
  1. acyl chloride
    CDCl2 + 2RMgX -> R2Cd
    * 2RCOCl + R2Cd-> 2 ketone + CdCl2
  2. RCN
    * RCN + RMgX (ether)then acid hydrolysis
  3. BEN
    friedel crafts acylation
    r/Ar -c=o cl in presence of anhydrous alcl3
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14
Q

higer bp of in aldehyde is due to

A

dipole dipole interaction which arises weak molecular ass

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15
Q

Arrange the following compounds in increasing order of their boiling points: CH3CHO, CH3CH2OH, CH3OCH3, CH3CH2CH3, CH3COCH3

A
  1. ch3ch2ch3
  2. ch30ch3
  3. ch3oh
  4. ch3coch3
  5. ch3ch2oh
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16
Q

the intermediste formed by nu- addition reaction of RCHO and RCOR’ i s>

A

tetrahedrasl alkoxide

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17
Q

aldehydes are more reactive toward NU +Rnx why?

A
  1. steric
  2. electronic
  3. the presence of 2 bulky alkyl grp hinders the approach of nu- to carbonyl carbon
  4. presence of 2 alkyl group reduces the electrophililitcutof the carbonyl carbonmore effect than in aldehyde
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18
Q

is benzaldehyde more reactive toward nucleophilic substitution reaction than propanal

A

In benzaldehyde, the polarity of carbonyl group decreases due to resonance. so carbon isless electrophilic
so it is less reactive than propanal

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19
Q

ald and ket react with HCN TO GIVE

what to do when the rnx is slow

A

cyanohydrins

it is catalysed by a base which gives cn- (cyanide ion) which is a stronger base readily add to C

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20
Q

WHY IS THE equi in largely to \rhs for alde and lhs for ket

A

due to steric reasons

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21
Q

why are hydrogen sulphite adn compound useful for separation of ald and its pruification

A

bisulphite addition compund is water soluble and can be concerted back to carbonyl comp with dil mineral acid or alkali

22
Q

hemi acetal

A

alkoxy alcohol

23
Q

acetal

A

gem diaalkoxy

24
Q

ethylene glycol ketal

A

ketone + ethylene glycol- HCL gas and dil. HCl-> ethylene glycol ketal

25
Q

why is dry hydrogen chloride used in adition of alcohol to aldehyde an dketone

A

What is the main function of dry HCl in the reaction?
Dry hydrogen chloride protonates the oxygen of the carbonyl compounds and therefore, increases the electrophilicity of the carbonyl carbon facilitating the nucleophilic attack of ethylene glycol

26
Q

ACETALS AND KETALS are hydrolysed with aq mineral acid to form

A

aldehy de adn keto

27
Q

hydroxylamine

A

NH2-OH

28
Q

SCHIFFS BASE

A

substituted imine
c=nR

29
Q

oxime

A

addition of hydroxylamine
C=N-OH

30
Q

nh2nh2

A

hydrazine

31
Q

what is useful for characterising ald an dket

A

2,4 dnp
dinitrophenylhydrazone

32
Q

reduction of ald and ket by zinc amalgam and HCLis

A

clemmenson reduction

33
Q

reduction of ald and ket by HYDRAZINE followed by HEAT WITH KOH/NAOH in high bp solvent like ethylene glycol

A

WOLF KISHNER REDUCTION

34
Q

tollens test
reagent
detects
occurs in

A

SILVER MIRROR PRODUCED BY ALDE DUE TO FORMATION OF SILVER METAL
ammoniacla silver nitrate 2[Ag(NH3)2]+ warm with
ALDEHYDE
alkaline med - 3OH-

35
Q

fehlings test
reagent
detects
medium

A

heat ald with feh reag -> reddish brown ppt due to formation od Cu2O
1.soln a- aq cu2so4
2.soln b- alkaline sodium pottasium tartarate (rochelle salt)
aldhyde (XXXaromatic aldehyde)
alkanie - 5OH-

36
Q

IODOFORM TEST
detects
reagent
does it affect C=C
does it detect CH3CH(OH) then why??

A

ch3-c=o + naOX(sodium hypoiodite)-> sodiun salt of RCOOH with one less carbon
methyl ketone
NaO I
it doesnt affect
yes cause ch3ch(oh)produces ch3 co on oxidation

37
Q

why is alpha H acidic

A

strong electron withdrawinf effect of carbonyl grpand resonance stabilisation gof conjugate base

38
Q

CANNIZARO RNX

A

HCHO AND BECHO basically COOK in ROH

WHEN COOKING HEAT NEEDED

39
Q

for ESR aromatic alde and keton + HNO3/H2SO3

273-283K

A

mNitrobenzaldehyde
cause ALDE AND KET meta directionf and deactivaitng

40
Q

NUMENCLATURE

HOOC-COOH🐂
HOOC-CH2-COOH

A
  1. ETHANEDIOIC ACID
  2. PROPANEDIOIC ACID
41
Q

JONES REAGENT

A

CRO3- H2SO4

42
Q

TEST TO SHOW RCOOH IS MORE ACIDIC THAN PHENOLS

A

Sodium hydrogen carbonate
NaHCO3

43
Q

STRONGEST RCOOH

A

TRIFLUOROACETIC ACID

44
Q

ACIDS OF pKa <1

A

strong acids

45
Q

pKa ~ 1 and 5

A

moderately strong

46
Q

pka>15

A

very weak

47
Q

pka ~ 5 to 15

A

weak

48
Q

why is RCOOH more acidic tha phenol

A
  • the carboxylate ion, the conjugate base of a carboxylic acid is s**tabilized by two equivalent resonance structures **in which the negative charge is effectively delocalized between two more electronegative oxygen atoms.
  • in phenoside ion , the conjugat base is stabilised by 2 non equivalent resonance str
  • negative charge is less effectively delocalized over one oxygen atom and less electronegative carbon atoms in phenoxide ion.
  • Therefore, the carboxylate ion exhibits higher stability in comparison to phenoxide ion and are more acidic
49
Q

how does electron withdrawing group increase the acidity of RCOOh

A

by delocalizing the charge of the carboxylate ion.by inductive or resonance effect

EDG DESTABILISES CARBOXYLATE

AND WEAKENS ACID

50
Q

RCOOH doesnt undero FCA

A

bcz carboxyl group is deactivating and the lewis acid alcl3 gets bonded to carboxyl grp

51
Q

DIRECT ATTACHment of phenyl or vinyl to RCOOH increases the acidity

A

greater electronegativity of sp2 hybridised c of RCOOH

Chemistry (9 decks)

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