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Neet 2024 > Haloalkanes And Haloarenes > Flashcards

Haloalkanes And Haloarenes Flashcards

1
Q

Which is most stable radical? Pg 88 qus 16

A

Allyl free radical is highly stable due to hyperconjugation

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2
Q

Preparation of alkyl halides from alkenes follow which mechanism?( Markovnikov rule)

A

Electrophilic addition and carbocation intermediate formation

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3
Q

Anti markovnikov rule follows which mechanism

A

Free radical addition

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4
Q

How can you prepare alkyl iodide

A

By halogen exchange method
Finkelstein reaction
In presence of acetone

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5
Q

Wat type of reaction is Finkelstein reaction

A

Nucleophilic substitution (SN2)

nacL / nabr being insoluble in acetone shift the equilibrium forward

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6
Q

How can you prepare alkyl fluorides

A

By swarts reaction
In presence of heavy metal fluorides ( ex - SbF3. Hg2F2 AgF)

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7
Q

Characteristic reactions of haloalkanes is

A

Nucleophilic substitution reaction

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8
Q

Wat is darzen’s process

A

Most preferred to prepare alkyl chloride

Uses thinoyl chloride (SOCL2)

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9
Q

Lucas reagent? Wat is use of lucas test?

A

Anhydrous ZnCL2. + Conc HCL

Lucas test distinguishes between primary secondary and tertiary alcohol

Primary mein turbidity mein time lagta
Tertiary mei nhi lagta

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10
Q

Wat is goorves precess

A

Reaction of alcohol with HCL to form alkyl halides in presence of anhydrous ZnCL2

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11
Q

Dipole moment of alkyl halides

A

R-CL. > R-F> R-Br > R-I

Although reactivity and boiling point RI ki sabse zyada

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12
Q

Why is grignard’s reagent prepared under anhydrous conditions?

A

Coz GR reacts with any source of acidic H to give alkane (ie reduction)

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13
Q

Which is the best departing halide?

A

Iodide

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14
Q

Ambidentate nucleophiles

A

CN- and NO2-
Posses two nucleophilic centres

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15
Q

Wat is williamson synthesis?

A

Preparation of ether (R-O-R’) from alkyl halide in presence of sodium alkoxide ie (R’O-Na+)

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16
Q

R-X with KCN will give?

A

R-CN ie alkyl cyanide

17
Q

R-X with AgCN will give?

A

R-NC ie alkyl isocyanide or carbyl amine

18
Q

RX with KNO2 will give?

A

R-ONO ie alkyl nitrite

19
Q

RX with AgNO2 will give

A

R-NO2 ie nitro alkane

20
Q

Tell about SN1 reaction

A

Rate only depends on concentration of alkly halide

Occur in polar protic solvents like water coz hydration energy se carbocation stable hote!!

Occurs in two steps. First is slow and rds and carbocation intermediate is formed

21
Q

Reactivity of alkly halides in SN1

A

3° > 2°> 1° one to sn1 dikhate hi nhi

This order is due to carbocation stability

22
Q

Benzylic and allylic halides prefer which nucleophilic substitution mechanism?

A

SN1 coz their carbocations are resonance stabilised

23
Q

Tell about SN2

A

Occur in single step

Complete inversion of configuration ie Walden inversion

In polar aprotic like dmf dmso

Rate depends on both nucleophile and alkyl halide ki concentration

24
Q

Give reactivity order for alkyl halide in SN2

A

1°>2°>3° due to steric hindrance

25
Q

Wat are expections to styzeff rule

A

If the base is bulky.. Hoffmann is major

If hindrance around beta hydrogen is large then Hoffmann

In case of Alkyl fluorides Hoffman is always major (mechanism E2)

26
Q

In which conditions is elimination preferred over substitution

A

When base(nucleophile )is bulky

When base is strong like OH- NH2-

When large steric hindrance in alkyl halide

Reaction conditions like high temperature

27
Q

Do primary alkyl halide prefer substitution or elimination?

A

Primary prefer substitution
While
Tertiary prefer elimination
(Due to steric hindrance)

Agar steric hindrance hogi to elimination prefer kiya jaata hai

28
Q

Wat is solvolysis

A

A reaction in which the substrate reacts with the solvent

29
Q

Which indergoes nucleophilic substitution exclusively by SN1

A

Benzyl chloride

30
Q

Boiling point of ortho para Meta ie aryl halides

A

Nearly the same but

O> p> m

31
Q

Melting point of arly halides

A

Para has much higher melting point.

P» o> m

32
Q

Orientation of attacking electrophile is governed by which effect?

A

+R effect

33
Q

Incoming electrophile attacks which positions?

A

Ortho and para

34
Q

Why don’t aryl and vinylic halides give nucleophilic substitution reaction under normal conditions

A

Partial double bond character of c-x bond

C(sp2)-x bond length is short and hence difficult to break

35
Q

Wat is the effect of EWG on reactivity of arly halides in nucleophilic substitution

A

EWG at ortho and para increases reactivity by stabilising the intermediate carbanion

36
Q

Wat is NBS

A

N bromo succinimide

Most preferred reagent for bromination of allylic free radical subsi .. taaki addition na ho coz ye limited bromine hi provide krega

37
Q

Chloropicrin is obtained by the reaction of

A

Nitric acid on chloroform

38
Q

Nbs is a specific reagent for?

A

Allylic substitution
N bromo succinimide

Neet 2024 (9 decks)

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