chem organic reactions Flashcards
1
Q
free radical substitution rnc
A
limited X2, UV light
2
Q
electrophilic addition rnc
A
br2 in CCl4
3
Q
alkene to CH3-CH2(X)
A
Dry HX(g) / HX on CCl4
4
Q
alkene to alcohol (CH3CH2OH)
A
- Conc H2SO4 followed by boiling/heating with water
2. Heat at high pressure with conc. H3PO4 as catalyst
5
Q
alkene to alkane
A
(reduction)
- H2 gas in the presence of high T and P
- Pd catalyst at rtp
- Pt catalyst at rtp
6
Q
alkene to diol
A
cold alkaline KMNO4 (oxidation)
7
Q
alkene to ketone/carboxylic acid/ carbonic acid then to CO2/H20
A
- hot acidified KMNO4
- hot KMNO4, dilute H2SO4
- hot alkaline KMNO4
8
Q
test for alkenes
A
- Add Br2 in CCl4, rtp in the dark
(decolourisation of orange Br2 solution) - Add cold alkaline KMNO4
(formation of brown ppt of MnO2) - Add hot acidified KMNO4
(decolourisation of purple KMNO4 solution)
9
Q
Alcohol to alkene
A
(elimination)
- Excess conc H2SO4, heat
- Al2O3 catalyst, heat
- Excess conc H3PO4, heat
(IMPORTANT!!)
10
Q
halogenoalkane to alkene
A
(elimination)
NaOH in ethanol, heat
11
Q
benzene to halogenoarene
A
X2 with anhydrous FeX3/AlX3/Fe
12
Q
benzene to nitrobenzene
A
conc HNO3 and conc H2SO4, 55°C
13
Q
benzene to alkylbenzene
A
CH3X with anhydrous FeX3/AlX3
14
Q
alkylbenzene to 2 or 4 nitromethylbenzene
A
conc HNO3 and conc H2SO4, 30°C
(lower temperature is required as compared to benzene due to the presence of the methyl group, which activates the benzene ring, more susceptible to electrophilic substitution)
14
Q
alkylbenzene to 2 or 4 nitromethylbenzene
A
conc HNO3 and conc H2SO4, 30°C
(lower temperature is required as compared to benzene due to the presence of the methyl group, which activates the benzene ring, more susceptible to electrophilic substitution)
15
Q
methylbenzene to 2-chloromethylbenzene or 2-bromomethylbenzene
A
X2 with anhydrous FeX3/AlX3/Fe IN THE DARK
16
Q
methylbenzene to CH2Cl(C6H5)
A
(FRS)
limited Cl2(g), UV light
17
Q
methylbenzene to benzoic acid
A
KMNO4 in dilute H2SO4, heat (oxidation)
18
Q
nucleophilic substitution (Sn2)
A
nucleophile (eg. OH-) with primary halogenoalkane
19
Q
nucleophilic substitution (Sn1)
A
nucleophile (eg. OH-) with tertiary halogenoalkane
20
Q
RX to ROH
A
NaOH (aq), heat
21
Q
RX to ROR’
A
Na in excess alcohol (R’O- Na+), heat
22
Q
RX to RCN
A
KCN in ethanol, heat under reflux
23
Q
RCN to RCOOH
A
HCl(aq) / H2SO4(aq), heat under reflux
24
RCN to RCH2NH2
1. LiAlH4 in dry ether
2. H2 with Ni catalyst, heat
3. H2 with Pd / Pt catalyst
25
RX to RNH2
Excess conc NH3 in ethanol, heat in sealed tube
| IMPORTANT
26
halogenoalkane to alkene
KOH or NaOH in ethanol, heat
27
test for halogenoalkane
heat the compound with NaOH (aq), followed by the addition of dilute HNO3. Add AgNO3
if white ppt -> RCl present
if cream ppt -> RBr present
if yellow ppt -> RI present
28
relative ease of hydrolysis of halogenoalkanes
(slowest) RCl>RBr>RI (fastest)
due to breaking of C-X bond hence depends on C-X bond strength
29
reactivity difference between halogenarenes and halogenoalkanes
For halogenoarenes, C-X bond shorter and stronger than those in halogenoalkanes. Lone pair on X atom is delocalised into the pi electron cloud of the benzene ring, strengthening the C-X bond in the halogenoarenes due to presence of partial double bond character. In addition, the pi electron cloud of the benzene ring will repel the lone pair of electrons of the incoming nucleophile, rendering attack of the nucleophile difficult.
29
reactivity difference between halogenarenes and halogenoalkanes
For halogenoarenes, C-X bond shorter and stronger than those in halogenoalkanes. Lone pair on X atom is delocalised into the pi electron cloud of the benzene ring, strengthening the C-X bond in the halogenoarenes due to presence of partial double bond character. In addition, the pi electron cloud of the benzene ring will repel the lone pair of electrons of the incoming nucleophile, rendering attack of the nucleophile difficult.
30
halogenoalkenes do not undergo NS because ____________
the lone pair on the X atom is delocalised into the pi bond of the adjacent C C double bond, strengthening the C-X bond due to presence of partial double bond character, hence NS do not occur in normal condition.
31
relative ease of hydrolysis of acyl chloride compared to alkyl and aryl chlorides
fastest RCOCH3 > RCL > C6H5Cl (doesnt even occur)
for RCOCH3, the carbonyl atom is bonded to 2 electronegative atoms O and Cl, making carbonyl C atom highly electron deficient and very susceptible to NS.
for RCl, there is only one electronegative Cl bonded to the alkyl C atom. Hence the alkyl C atom is less electron deficient and less susceptible to NS.
for C6H5Cl, the lone pair of electrons on the Cl atom is delocalised into the benzene ring, strengthening the C-X bond due to presence of partial double bond character, hence NS does not occur.
31
relative ease of hydrolysis of acyl chloride compared to alkyl and aryl chlorides
fastest RCOCH3 > RCL > C6H5Cl (doesnt even occur)
for RCOCH3, the carbonyl atom is bonded to 2 electronegative atoms O and Cl, making carbonyl C atom highly electron deficient and very susceptible to NS.
for RCl, there is only one electronegative Cl bonded to the alkyl C atom. Hence the alkyl C atom is less electron deficient and less susceptible to NS.
for C6H5Cl, the lone pair of electrons on the Cl atom is delocalised into the benzene ring, strengthening the C-X bond due to presence of partial double bond character, hence NS does not occur.
32
solubility of alcohols in water decreases as no. of C atoms in the alcohol increases because ___________
the larger non polar R group makes the molecule more hydrophobic in nature. The extent of IDID between R groups of the molecule is more significant than the extent of hydrogen bonding between the alcohol molecules and the water molecules.
33
alcohol to ester
COOH, conc H2SO4 catalyst, heat
34
alcohol to ester pt 2
RCOCl (condensation)
35
alcohol to aldehyde
K2Cr2O7 in dilute H2SO4, heat with immediate distillation
36
alcohol to carboxylic acid
1. K2CrO7 in dilute H2SO4, heat
| 2. KMNO4 in dilute H2SO4, heat
37
aldehyde to carboxylic acid
1. K2CrO7 in dilute H2SO4, heat
| 2. H2SO4 in dilute H2SO4, heat
38
iodoform products for RCH(CH3)(OH) 4I2 and 6NaOH
RCOO-Na+ + CHI3 (yellow ppt) + 5NaI + 5H2O
39
aldehyde to pri alcohol
1. LiAlH4 in dry ether
2. NaBH4 in ethanol
3. H2 in Ni catalyst, high T and P
4. H2 in Pt or Pd
40
ketones to sec alcohol
1. LiAlH4 in dry ether
2. NaBH4 in ethanol
3. H2 in Ni catalyst, high T and P
4. H2 in Pt or Pd
41
tests for alcohols
1. add anhydrous PCl5 to compound
(white fumes of HCl observed)
2. heat the compound with KMNO4 in dilute H2SO4
(decolourisation of purple KMNO4 solution)
42
why is phenol the most acidic amongst water and ethanol?
in phenoxide ion, the lone pair of electrons on the oxygen atom is delocalised into the benzene ring that results in the dispersal of the negative charge on the phenoxide ion, hence stabilising the phenoxide ion.
43
phenol to phenoxide
1. reactive metal (eg. Na and K) to form O-Na+
| 2. NaOH (aq) (neutralisation)
44
phenol does not react with carboxylic acid because ________
phenol is a weaker nucleophile than an alcohol since the lone pair of electrons on the O atom is delocalised into the benzene ring.
45
phenol to ester
ROCl (nucleophilic acyl substitution)
46
phenol more susceptible to ES compared to benzene because ________
in phenol, the lone pair of the electrons on O atom is delocalised into the benzene ring thereby increasing the electron density in the ring, hence increasing reactivity towards ES
47
phenol to 2-nitrophenol or 4-nitrophenol
HNO3 (aq), rtp
48
phenol to 2,4,6-trinitrophenol
conc HNO3
49
test for phenol
1. Br2 (aq)
(decolourisation of orange Br2 (aq) and formation of white 2,4,6-tribromophenol)
2. neutral FeCl3 (aq)
(violet complex observed)
50
Nucleophilic Addition product: hydroxynitrile
HCN with trace amounts of NaOH as catalyst, cold
51
test for carbonyl compounds
2,4-DNPH, heat
| orange ppt
52
test to distinguish ketone and aldehyde
Tollens' reagent, heat
| aldehyde: silver mirror
53
test to distinguish aliphatic and aromatic aldehyde
Fehling's reagent, heat
| aliphatic: brick red ppt
54
iodoform test for RCOCH3
| to form RCOO-Na+ +CHI3 + 3NaI + 3H2O
alkaline I2(aq)
55
concept about acidity
strength of acid depends on the stability of the conjugate base
the more dispersed the negative charge on the carboxylate anion, the more stable the conjugate base and hence stronger acid
56
carboxylic acid is stronger than alcohols and phenols because ______
the carboxylate (COO-) is resonance stabilised by the delocalisation of the negative charge over the C atom and both electronegative O atoms in the anion.
The intensity of the negative charge on the anion is less than that of the phenoxide or alkoxide ion, hence anion more stable.
57
carboxylic acid to pri alcohol
LiAlH4 in dry ether
58
RCOOH to RCOO-Na+
reactive metals (eg. Na , Mg, Ca)
59
RCOOH to RCOO- part 2
NaOH(aq) / KOH(aq) / Ca(OH)2 (aq)
60
RCOOH to 2RCOO-Na+
Na2CO3 (aq)/(s)
61
RCOOH to RCOO-Na+ pt 3 of carbonates
NaHCO3 (aq)/(s)
62
esterification of COOH with OH
RCOOH and OH to form COO
| conc H2SO4 as catalyst, heat
63
RCOOH to RCOCl
1. anhydrous PCl5
2. anhydrous PCl3
3. anhydrous SOCl2
64
HCOOH oxidised to give _______
| methanoic acid
CO2 and H2O
KMNO4 or K2CrO7, dilute H2SO4, heat
65
(COOH)2 oxidised to give ______
| ethanedioic acid
2CO2 + H2O
KMNO4 in dilute H2SO4. heat
NO K2CRO7!!!
66
test for COOH
1. add NaCO3
(effervescence of CO2 that forms white ppt with Ca(OH)2)
2. anhydrous PCl5
(white fumes of HCl)
67
ester to COOH
H2SO4(aq) / HCl (aq), heat under reflux
68
ester to RCOO-Na+
NaOH(aq), heat under reflux
69
amines have higher bp than hydrocarbons with same Mr due to ________
stronger intermolecular hydrogen bonding
70
amines have lower mp than alcohol of similar Mr due to _________
intermolecular hydrogen bonding in amines being weaker than those in alcohol since the N-H bond is less polar than O-H bond
71
pri amide to pri amine
LiAlH4 in dry ether
72
nitrobenzene to phenylamine
Sn in excess conc HCl and heat
followed by NaOH(aq)
(REDUCTION AND IMPORTANT!!!)
73
ethylamine is a stronger base than ammonia because ________
electron donating alkyl group increases the electron density of the lone pair on N atom, hence lone pair on N atom is more available to accept a proton.
74
relative basicity of aliphatic amines in gaseous phase
NH2(CH3) vs NH(CH3)2 vs N(CH3)3
most basic tri>di>methylamine
increase in no. of alkyl groups increases the electron density of the lone pair on N atom, hence lone pair on N atom is more available to form A DATIVE BOND.
75
R-NH2 to R-NH3+
HCl (aq) or H2SO4 (aq)
76
amine to amide
anhydrous RCOCl (condensation)
77
phenylamine to 2,4,6-tribromophenylamine
Br2 (aq) (ES)
(decolourisation of orange Br2 solution with the formation of white ppt
78
why are the conditions required to form 2,4,6-tribromophenylamine from phenylamine mild? (no catalyst required)
phenylamine is more reactive then benzene towards ES as the -NH2 group activates the ring towards ES. This is due to lone pair on N atom being delocalised into the benzene ring hence increasing electron density in the ring
79
amides are neutral and no basic because__________
the lone pair on N atom is delocalised into the pi bond of the adjacent C O double bond hence reducing the electron density on the N atom, lone pair on N atom is less available to accept a proton
80
amides to RCOOH and NH4+
HCl (aq) / H2SO4 (aq), heat under reflux
81
amides to RCOO-Na+ and NH3
NaOH(aq), heat under reflux
| PUNGENT NH3 CONFIRMS AMIDE IS PRIMARY
82
test for amides , NH4+X and amine
NaOH(aq)
| turn moist red litmus paper blue as NH3 gas is produced
