ALKYL HALIDE · GRIGNARD REAGENT · ALCOHOL · ETHER
All Major Reactions + 50 Tough MCQ

(A) PhCH₂OH (phenylmethanol)

(B) PhCH₂CH₂CH₂OH (3-phenylpropan-1-ol; primary alcohol, chain +2C)

(C) PhCH₂CH₂OH (2-phenylethanol; primary; chain +2C) ✓

(D) PhCHO (benzaldehyde by oxidation)

(A) Retention of configuration (R)-product (SNi)

(B) Inversion to (S)-2-chlorobutane (SN2 via chlorosulfite; pyridine drives backside attack)

(C) Racemisation (SN1 through carbocation)

(D) Elimination to but-2-ene (E2)

(A) Propan-1-ol (1-hydroxypropane)

(B) Propan-1,2-diol with OH at C2 (more substituted) → propylene glycol; nucleophile attacks at C2 (more carbocation character)

(C) Propan-1,3-diol (1,3-propanediol)

(D) Propanal by rearrangement

(A) R–OH (alcohol)

(B) RCHO (aldehyde)

(C) RCOOH (carboxylic acid; one carbon added as –COOH)

(D) R–R (coupling)

(A) PhO–C(CH₃)₃ (t-butyl phenyl ether)

(B) Mainly isobutylene (2-methylpropene) + PhOH (E2 with PhO⁻ acting as base; 3° halide always gives E2 in Williamson)

(C) SN2 product (Ph–O–C(CH₃)₃) via inversion

(D) No reaction; PhO⁻ cannot act as base

(A) Hexanedioic acid (adipic acid)

(B) Hexanal (stops at aldehyde; PCC is mild; does not over-oxidise to acid)

(C) Hexanoic acid (full oxidation)

(D) 2-Hexanone (isomerisation)

(A) PhI + CH₃CH₂OH (aryl C–O cleaved by SN2)

(B) PhOH + CH₃CH₂I (alkyl C–O cleaved; Ar–O bond NOT broken by SN2 at sp² C)

(C) Ph–I + CH₃CH₂OH + I₂

(D) PhOCH₂I + CH₃OH (rearrangement)

(A) SN1 — LiAlH₄ ionises R–Br first

(B) SN2 — H⁻ (hydride) from LiAlH₄ attacks carbon with inversion; Br⁻ departs

(C) Radical mechanism (Al radical transfers H•)

(D) E2 followed by hydrogenation

(A) Acetic acid + methane

(B) 2-Methyl-2-propanol (t-butanol) — two CH₃ groups add to ester; ketone intermediate reacts with second Grignard → 3° alcohol

(C) Methanol + acetaldehyde

(D) 3-Pentanol (wrong carbon count)

(A) I⁻ is a better nucleophile than Cl⁻ in polar aprotic solvents

(B) NaCl precipitates from acetone (insoluble); Le Chatelier principle drives equilibrium toward R–I; combined with I⁻ being softer nucleophile — both factors operate

(C) NaI is more soluble than NaCl in all solvents

(D) SN1 mechanism; I⁻ traps the carbocation faster

(A) SN2 — Cl⁻ displaces OH directly from 3° carbon

(B) SN1 — ZnCl₂ coordinates OH, assists ionisation → 3° carbocation → Cl⁻ attacks; R–Cl (insoluble in reagent) causes turbidity

(C) E2 — water is eliminated first then HCl adds

(D) Radical substitution

(A) Primary alcohol

(B) Aldehyde

(C) Ketone (no α-H on C=O side; oxidation stops at ketone from 2°)

(D) Carboxylic acid (only from primary alcohol)

(A) K₂Cr₂O₇ / H₂SO₄

(B) KMnO₄ / H₂SO₄

(C) PCC (pyridinium chlorochromate) in CH₂Cl₂

(D) MnO₂ is incorrect here; PCC is correct

(A) CH₃OH + (CH₃)₃CBr / NaOH → mainly ether (SN2)

(B) (CH₃)₃CO⁻Na⁺ + CH₃Br / DMSO → t-Bu–O–CH₃ (SN2 on CH₃Br; avoid 3° halide which gives E2)

(C) CH₃O⁻Na⁺ + (CH₃)₃CCl → t-Bu–O–CH₃ (SN2 on 3° — incorrect; gives isobutylene)

(D) (CH₃)₃COH + CH₃OH / H₂SO₄ → direct etherification

(A) Dry ether (solvent)

(B) Any compound with a proton more acidic than R–H (pKa < ~50): H₂O, ROH, RC≡CH, NH₃, carboxylic acids

(C) Only strong acids like HCl

(D) Ketones (react but do not destroy)

(A) 1,2-Propanediol with OH at C2 (more substituted) — via SN1-like

(B) 1,2-Propanediol with OH at C1 (less substituted); OH⁻ attacks less hindered C1 (SN2); inversion at C1

(C) Propan-1-ol by total reduction

(D) Acetaldehyde by Meinwald rearrangement

(A) HCl forms from ethyl chloride impurity

(B) Diethyl ether peroxide (explosive) forms by radical chain autoxidation of α-C–H bonds; must test with starch-iodide paper before use

(C) Diethyl ether polymerises to form a polymer

(D) Ether absorbs water and becomes corrosive

(A) Dimethyl ether (CH₃OCH₃)

(B) Ethanol (CH₃CH₂OH; primary alcohol; Grignard adds 1C to HCHO)

(C) Acetaldehyde (CH₃CHO)

(D) Methanol (CH₃OH)

(A) Inverted to (S); SN2 occurred at C2

(B) Retained as (R); TsCl reacts at S (sulfur of tosyl), not at C2; C–O bond of alcohol is NOT broken; configuration at C2 unchanged

(C) Racemised; radical mechanism at C2

(D) (R) to (S) because pyridine drives inversion

(A) SN1: 1° alcohol ionises to 1° carbocation; second alcohol attacks

(B) SN2: protonated alcohol (oxonium ion) undergoes SN2 by a second alcohol molecule as nucleophile at the primary C; 1° substrates only

(C) E2: both alcohols eliminate water simultaneously

(D) Radical coupling under acidic conditions

(A) Ph₃PH + RCHBr (radical)

(B) Ph₃P + RCHBr₂ → phosphonium salt; then base → ylide (SN2 at C then α-deprotonation)

(C) Ph₃P + RCH₂OH (alcohol)

(D) Ph₃P + RCHO (aldehyde reacts directly)

(A) The more substituted carbon (SN1-like)

(B) The less hindered (less substituted) carbon via SN2; H⁻ attacks least hindered C; inversion at that carbon

(C) Both carbons equally (racemic mixture)

(D) The carbon bearing the oxygen (O attacked, not C)

(A) Inversion → (S)-2-chlorobutane

(B) Retention → (R)-2-chlorobutane (Cl delivered from same face via cyclic 4-centre TS)

(C) Racemisation

(D) No stereoselectivity

(A) PhCHO (aldehyde; no — Grignard reduces not oxidises)

(B) 2-Phenyl-2-propanol (Ph–C(OH)(CH₃)₂; 3° alcohol; Ph adds to ketone C=O)

(C) Diphenylmethanol (requires benzophenone)

(D) Phenol + acetone (decomposition)

(A) R–OH (alcohol)

(B) R–R' (new C–C bond; SN2 by soft cuprate on soft alkyl halide; no elimination)

(C) R–X + R'–X (halogen exchange)

(D) R–O–R' (ether)

(A) Ethanol (primary → gives acid eventually)

(B) 2-Propanol (secondary → acetone, a ketone)

(C) 2-Methyl-2-propanol (tertiary → no oxidation; no α-H to C=O)

(D) Methanol (primary → gives formic acid)

(A) 3° alkyl halides (most stable cation for radical)

(B) Primary alkyl halides (least steric; radical/ionic; gives good yield of symmetrical alkane)

(C) Aryl halides (most reactive)

(D) Tertiary halides give Wurtz exclusively

(A) D₂O oxidises PhMgBr

(B) PhMgBr is a strong base (pKa of Ph–H~43); D₂O (pKa~15.7) is far more acidic; proton (deuteron) transfer gives Ph–D + MgBr(OD); protonolysis

(C) D₂O adds across the phenyl ring (1,4-addition)

(D) No reaction; PhMgBr is stable in D₂O

(A) E2 — H₂SO₄ acts as a base

(B) E1 — protonation of OH → oxonium ion → H₂O leaves → 3° carbocation → proton lost to solvent → alkene

(C) SNi — internal migration

(D) E1cb — carbanion at α-C

(A) Pentan-3-ol (wrong; two Grignards needed)

(B) Pentan-3-one? No — EtMgBr + CH₃CN → CH₃C(=NMgBr)Et → H₃O⁺ → methyl ethyl ketone (CH₃COC₂H₅) via imine hydrolysis

(C) Butanenitrile (no reaction)

(D) Ethylamine + acetic acid

(A) Alkyl groups are electron withdrawing, destabilising the alkoxide

(B) Alkyl groups donate electrons (+I) to oxygen, increasing electron density on O and destabilising the alkoxide anion; water has H (least donating) so H₂O is slightly more acidic than ROH

(C) Alkyl groups block proton removal sterically

(D) Alkoxide is aromatic and hence more stable than hydroxide

(A) C1 (less substituted) via SN2 (acidic conditions)

(B) C2 (more substituted, tertiary) — acid protonates O → more carbocation character at tertiary C2; Br⁻ attacks the more substituted C (Markovnikov-like; SN1 character)

(C) Equal attack at both C1 and C2

(D) Oxygen is attacked, not carbon

(A) The oxidant (Et₃N oxidises the alcohol)

(B) A base that abstracts the α-H from the alkoxysulfonium intermediate, triggering elimination to give the aldehyde (and dimethyl sulfide)

(C) A solvent in the Swern reaction

(D) A catalyst for DMSO activation only

(A) Retention (PPh₃ assists front-face delivery)

(B) Inversion (SN2 — carboxylate attacks the activated oxyphosphonium from backside); this is how Mitsunobu inverts alcohols

(C) Racemisation via radical

(D) Retention only when DIAD is absent

(A) Ag⁺ oxidises the alkyl group

(B) AgNO₂: Ag⁺ coordinates at N, forcing O-end to attack (O is the nucleophile in tight ion pair); KNO₂ in polar aprotic: free NO₂⁻, softer C-end attacks (harder C–N bond forms); ambident nucleophile regiochemistry controlled by cation and solvent

(C) KNO₂ is basic enough to cause E2

(D) Ag⁺ reduces NO₂⁻ to NO which reacts differently

(A) Use of a base to neutralise the acid product

(B) Large excess of alcohol OR azeotropic removal of water (Dean-Stark trap with benzene or toluene); both remove product from equilibrium; H₂SO₄ catalyses but cannot shift equilibrium alone

(C) Use of NaHCO₃ to buffer the acid

(D) High pressure drives the reaction; temperature has no effect on yield

(A) Diethyl iodide + water (two carbons iodinated)

(B) CH₃CH₂OH + CH₃CH₂I (one equivalent HI); I⁻ (soft, good SN2 nucleophile) attacks less hindered C of protonated ether; mechanism: protonation of O → SN2 by I⁻ → ethanol + ethyl iodide

(C) CH₄ + CH₃I + H₂O (complete fragmentation)

(D) Diethyl peroxide + HI (redox reaction)

(A) The Grignard reagent is still formed but more slowly

(B) Water reacts with RMgBr as it forms (protonolysis): RMgBr + H₂O → R–H + Mg(OH)Br; no Grignard accumulates; reaction fails

(C) MgBr₂ precipitates out and cannot react

(D) Water catalyses Grignard formation

(A) PhCHO + 2 CH₃MgBr → H₃O⁺ → Ph–C(CH₃)₂OH? No — 2nd Grignard cannot add after 1st addition to aldehyde gives 2° alcohol; only 1 Grignard adds to aldehyde

(B) PhCHO + 1 CH₃MgBr → H₃O⁺ → PhCH(OH)CH₃ (2° alcohol); to get 3°: use ketone e.g. PhCHO oxidised to PhCOCH₃ then + CH₃MgBr → Ph–C(CH₃)₂–OH (3°)

(C) PhCHO + CH₃MgBr → then + another Grignard → 3° via ester intermediate

(D) PhCHO + 2 equivalents of PhMgBr → triphenylmethanol (3° alcohol) — NOT possible with PhCHO; need PhCOPh (benzophenone)

(A) Swern oxidation

(B) Meerwein-Ponndorf-Verley (MPV) reduction — same Al-mediated 6-membered cyclic TS; H transfers from iPrOH to ketone in MPV; reversed here (H from substrate to acetone)

(C) Baeyer-Villiger oxidation

(D) Wacker oxidation

(A) t-BuOH has a lower pKa so reacts faster

(B) The rate of reaction with Na is KINETIC (access of Na surface to O–H); steric bulk of t-Bu slows approach to Na surface; EtOH less hindered, faster. Thermodynamic acidity (pKa) and kinetic rate are independent for heterogeneous reactions

(C) t-BuONa is more soluble in t-BuOH, retarding the reaction

(D) Na reduces t-BuOH to t-butane

(A) DMSO converts KCN to KNC

(B) In DMSO, CN⁻ is a free ion; softer C-end attacks soft CH₃Br (SN2, soft-soft); AgCN forms tight covalent Ag–N bond at N, forcing the C-end of CN away, and O-end (now N-end) cannot attack — actually Ag coordinates at N(?) — correction: Ag coordinates at C, forcing N-end attack in ion pair → isocyanide

(C) Temperature determines C vs N attack

(D) Methyl iodide is needed for isocyanide; bromide gives nitrile in all conditions

(A) But-1-ene (less substituted; Hofmann product)

(B) But-2-ene (major; Zaitsev; more substituted alkene from E1 via 2° carbocation — partial 1,2-H shift also gives but-2-ene dominantly)

(C) Dibutyl ether (intermolecular; wrong temperature)

(D) Butan-2-one (ketone; wrong reaction type)

(A) Aliphatic C–C bond formation

(B) Synthesis of biaryls (Ar–Ar); Cu couples two aryl halides by radical mechanism; 1° alkyl halides cannot be used

(C) Reduction of aryl halides to arenes

(D) Formation of aryl ethers from two aryl halides

(A) CH₃CH₂O⁻ + (CH₃)₂CHBr [2° halide; SN2 possible; some E2 may occur]

(B) (CH₃)₂CHO⁻ + CH₃CH₂Br [1° ethyl bromide + isopropoxide; best yield; SN2 on 1° with no E2 competition]

(C) (CH₃)₂CHCl + CH₃CH₂ONa [2° chloride; more E2]

(D) (CH₃)₂CHBr + CH₃CH₂ONa [2° bromide; more E2 competition than 1°]

(A) H⁻ adds syn to the epoxide oxygen

(B) H⁻ (hydride) attacks the less hindered carbon of the epoxide from the back (SN2); inversion at the carbon attacked; since both C1 and C2 are equivalent in cyclohexene oxide, attack at either gives trans-cyclohexan-1-ol (racemic) — actually only one alcohol product since only one C–O cleaved

(C) The ring opens without any stereospecificity

(D) LiAlH₄ first reduces epoxide O to OH by direct protonation

(A) EtMgBr + propionaldehyde (CH₃CH₂CHO) → 3-pentanol (not 2-pentanol)

(B) CH₃MgBr + butyraldehyde (CH₃CH₂CH₂CHO) → CH₃CH₂CH₂CH(OH)CH₃ = 2-pentanol ✓ (methyl Grignard + C4 aldehyde)

(C) n-PrMgBr + HCHO → butan-1-ol (primary)

(D) n-BuMgBr + HCHO → pentan-1-ol (primary)

(A) PhO⁻ is a soft nucleophile; 3° halides are soft electrophiles

(B) (CH₃)₃CBr is a 3° halide; PhO⁻ acts as a base (E2) abstracting β-H from the 3° substrate; elimination dominates over substitution; CH₃Br (primary) → SN2 dominates

(C) PhO⁻ is too large to attack (CH₃)₃CBr

(D) PhO⁻ reacts with (CH₃)₃CBr by SN1; PhO⁻ attacks the formed t-Bu cation

(A) SN2 reaction between two acetone molecules

(B) Reductive coupling of two carbonyl compounds via ketyl radicals (C=O + e⁻ → •C–O⁻); two radicals combine at C; gives vicinal diol (1,2-diol)

(C) Aldol condensation under acidic conditions

(D) E2 elimination from a diacetone compound

(A) Pyridine is the nucleophile that attacks Ac₂O; acylpyridinium forms; alcohol then attacks the activated acylpyridinium (better electrophile) → ester + pyridine regenerated

(B) Pyridine is just a solvent

(C) Pyridine deprotonates the alcohol to make a more reactive alkoxide

(D) Pyridine reacts with acetic acid by-product preventing reverse reaction only