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alcohols Flashcards

1
Q

why is the c-o-h bonde angle less in alcohola as compared to tetrahedral angle (109.28)

A

due to repusionbtwn unshaired e- pairs of O2

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2
Q

why is bond lenght in phenol slightly less than in methanol

A

This is due to partial double bond character on account of the conjugation of unshared electron pair of oxygen with the aromatic ring and a sp2 hybridised state of carbon to which oxygen is attached.

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3
Q

in ethers bond angle is slightly more than tetrahedral angle

A

repulsive interaction of bulky R grp

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4
Q

mechanism of acid catalysed hydration

marks rule

A
  1. protonation of C=C to form C+ by electrophilic attacvk of H2O
  2. NU:- attack of H2O on C+
  3. deprotonation to form alcohol
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5
Q

addition product of renx of diborane(H-BH2)2 with C=C

anti mark

A

trialkyl borane

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6
Q

COMErcial preparation of alchol from RCOOH

LiAlH4 is expensive

A
  1. add lil R’OH / H+
  2. RCOOR’
  3. CATALYTIC HYDROGENATION
  4. RCH2OH + R’OH
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7
Q

carbolic avid

A

phenol

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8
Q

comercial preparation of phenol

A

cumene
isopropyl benzene

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9
Q

benzene sulphonic acid is prepared by

A

benxene + oleum

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10
Q

nitrous acid used in preparation of diazonium salt at 273- 273K is

ride - warm water

A

NaNO2 + HCl

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11
Q

by product o phenol prepared by cumene is

A

acetone

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12
Q

oxidation of cumene in presence of air

A

cumene hydroperoxide

after that H+/ H20-> phenol + acetone

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13
Q

what happens when elimination competes over subtitution in dehydration of alcohols

A

alkenes are formed

ROH + h2so4 in 443K

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14
Q

dehydration of alcohol to form ether at 413K in prsene of protic acid like h2so4 is which mechanism

A

sn2

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15
Q
A
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16
Q

how are phenols converted to ethers

A

williamson

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17
Q

in BP no. of C atom increases what happens to van der waals force

A

increases

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18
Q

why does with increase in branching BP decrease

A

vander waals force decrease

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19
Q

high BP of R-OH is due to

ROH> ROR’ > RR

A

intermolecular H bonding

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20
Q

why does with increase in alkyl part solubility decreases

A

due to increase in HYDROPHOBIC CHARACTER of alkyl grp

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21
Q

which bond is broken when alco🪓hol is nuclephile

A

oh

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22
Q

which bond is broken when alc🪓ohol is electrophile

A

co

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23
Q

how is polarity related to acid strenght

A

polarity decreases acid strenght decreases

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24
Q

test to show phenols more acidic than ROH

A

Ar -O -H +NaOH-> Ar-ONa +H2O

sodium phenoxide +water

25
how do u explain the acidic strength of ROH 1o>2o>30
as ERG (-ch3, c2h5) increase e- density on O this decrease polarity of O- H bond this decreases acid strenght
26
show water is more acidic than alcohol
R::O:- + H-:O:-H -> ROH + :::OH base + acid -> conjugate acid + conjugate base
27
why does alcohol act as bronsted bases
Due to presence of lone pair of electrons on oxygen atom, alcohols accept a proton which makes them Bronsted base
28
Alcohols act as Bronsted acid and Bronsted base both Explain
Due to presence of lone pair of electrons on oxygen atom, alcohols accept a proton which makes them Bronsted base and due to acidic hydogen they donate the proton to strong base which makes them Bronsted acid.
29
why does polarity of O-H in phenol increases
due to high electronegativity of sp2 C to which O-H is attached e- density decrease and polarity increases
30
why is thepresence of EWG enhance the acidic strength more pronanciicng at *o and p* posts
due to effective delocatisation of -ve charge in phenoxide ion when substituent is at *o and p* post
31
what does reactind RCOOH, RCOCl, (RCO)2with ROH gives
ESTER RCOOR'
32
THE rnc with RCOOH and (RCO)2 is carried out in the presence of small amount of conc H2SO4but RCOCl is carried out in pyridine whyy
to neutralise HCL and shift EQUILIBRIUM to RHS
33
ACETYLATION
THE INTRO OF ACETYL GROP CH3CL in alcohols or phenols
34
acetylation of salicylic acid gives
ASPIRIN (acetyl salicylic acid)
35
how do u differentiate 1o 2o and 3o alcohols
by lucas test (HCl +ZnCl2) 3o- turbidity immediately 2o - turbidity after few mins 1o - X turbidity at rooom temp
36
which bond is cleaved when phenol react with zn
c-o
37
by product of R-OH reacted with phosphorus trihalide
H3PO3
38
Ethanol + heat at 443K + con h2so4gives
ethene undergoes DEHYDRATION
39
PROPAN-2-Ol with 85% h3po4 at 440K
ch3-ch=ch2 + h2o
40
2 methylpropan-2-ol react with 20% h3po4 at 358K
2 methylpropene
41
mechanism of DEHYDRATION | 3o>2o>1o
1. formation of protonated alchol 2. formation of C+ (slowes and rate deter) 3. formation of ethene by elimination of proton ## Footnote to drive hte equi to the right ethene is removed
42
which all bond are cleaved in alcohol to for C=O durind oxin and is called
C-H and O-H dehydrogenation
43
under high temp and strong oxi agents tertiary alcohols cleave various C-C bond to forms >?
mixture of RCOOH containing lesser no. of C atoms
44
what happens when vapors of 1. 1o 2. 2o 3. 3o alcohols are passed over heated cu at **573K**
1. RCHO 2. RC=OR' 3. dehydration: alkene is formed
45
how OH group **activates** the incoming electrophile to *o and p* posts
OH group exerts +R effect on the benzene ring. So, electron density in the ring increases particularly at the ortho and para positions
46
phenol + dil nitric acid gives | 298K
phenol + dil.HNO3-> o and p- nitro phenol
47
phenol + con nitric acid gives
phenol + dil.HNO3-> 2,4,6-Trinitro phenol aka picric acid
48
how do u separate o and p- nitro phenol
separated by steam distillation * *o *- nitroph is steam volatiledue to intramolecular h bonding * *p* - nitroph is less volatile due to intermolecular h bonding which causes association of molecules
49
phenol + halogen in chcl3/CS2 ->
monohalophenols
50
why is halogenation of phenols occur in the absence of lewis acid feBr3
in usual halogentaion of benzene the lewis acid polarises the halogen molecule due to high activating effect oF OH grp polarisation of bromine occurs even wothout lewis acis FeBr3
51
when ph is reacted with bromine water
2,4,6-tribromoph + 3HBr white ppt
52
kolbe's rnx
ph+ NaOH-> ph-ONa+ -(i)CO2/(ii)H+-> **SALICYLIC ACID** ## Footnote phenoxide is more reactive so it undergoes ESR wih CO2. a weak electrophile
53
REIMER - TEIMANN
ph+ chcl3 +aq NAOH-> intermediate- NAOH->phONa+&CHO -H+-> **SALICYLALDEHYDE**
54
IN PRESENCE OF AIR, phenols are oxidised to dark coloured mixture :
quinones
55
🌴👻 | colourlss and bp-337K
methanol ch3oh | catalytic hydrogention with zno+cr203 ## Footnote 200-300atm and 573 to 673K
56
what is added to ethanol(bp- 351K) to denature its colour and smell
colour- copper sulphate smell - pyridine
57
which alkyl grpsin 1o and 2o are attacked by iodine(nucleophile)by SN2 mechanism
the lower on*ch3I*
57
alkyl aryl ethers are cleaved at the alkyl O2 bond??
due to stability of aryl O2 bond
58
or GROUP IS ACTIVATING AN D--- directing
*o and p*

Chemistry (9 decks)

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