Haloalkanes/Arenes

Question 1

Haloalkane classification basis?

Answer 1

Hybridization and no. Of H atoms

Question 2

On basis of no.of X?

Answer 2

Mono,dia,tri

Question 3

Diaalkylhalide futher classified into?

Answer 3

Geminal and vicinal

Question 4

Geminal and vicinal ?

Answer 4

Geminal: jb ek carbon pr do x attach ho
Vicinal: jb do adjacent carbons pr X attach ho(dono pr)

Question 5

Hybridization classification?

Answer 5

Sp2 and sp3

Question 6

Sp2 is divided into?

Answer 6

Vinylic and aryl

Question 7

Vinylic and aryl?

Answer 7

Vinylic: X directly ek doubly bonded C se attach hota h
Aryl: X directly benzene ring se attached h

Question 8

Sp3 is divided into?

Answer 8

Allylic and benzylic

Question 9

Allylic and benzylic?

Answer 9

Allylic: X ek aise C se attach ho jo further ek doubly bonded C se attach ho
Benzylic: X ek C se attach h jo directly benzene ring se attached h

Question 10

Name the methods of preparation of haloalkanes[RX]? 4methods

Answer 10

(1) From alcohol[ROH]
(2)From hydrocarbon[HC]
(3) Finkelstein
(4)Swarts

Question 11

All prep from ROH?

Answer 11

1. ROH me HX (x=cl,br,I) in presence of zncl2 gives RX. {If hcl is added with zncl2 it’s lucas reagent}
   2.ROH me pcl3 add krne pr RX milega and h3po3 byproduct
   3.ROH me pcl5 add krne pr RX milega and pocl3 byproduct
   4.ROH me socl2(thionylchloride) add krne pr RX milega and so2 ,hcl byproduct{only way to get pure RX as gases a liberated}

Question 12

All prep from HC?

Answer 12

1. From alkane
   >Free radical halogenation (X=cl,br) occurs in presence of sunlight only{X=F not possible as F is higly reactive and X=I not possible as it’s reversible very slow rxn}
   2.From alkenes
   > Bromination in which using markonikov major product is formed them using antimarkonikov minor product is formed {necessary to mention both}
   3.From alkenes
   >If only HX is given apply markonikov if with HX peroxide is present apply antimarkonikov

Question 13

For prep of RI?

Answer 13

Finkelstein: RX reacts with NaI in presence of dry ether to give RI {X=cl,br}

Question 14

For prep of RF?

Answer 14

Swarts: RX reacts with (AgF,CoF2,Hg2F2,SbF3) to give RF

Question 15

Name all the prep methods for haloarenes?

Answer 15

1.Diazonium salt
2. Halogenation

Question 16

Mop of haloarenes by halogenation?

Answer 16

1. Benzene reacts with cl2 in presence of FeCl2 within dark and cold conditions to give haloarenes.
2. Toluene reacts with cl2 in presence of Fe within dark and cold conditions to give ortho and para isomers of chlorotoluene

Question 17

Mop of haloarenes by diazonium salt?

Answer 17

For making diazoinium salt
In aniline we add NaNO2+HCl (at 273-278k) gives➡️benzene diazoinium chloride (BDC)

1.Sandmeyers
>BDC reacts with Cu2X2 + HCl (X=F,Cl) to give ➡️haloarene
2.Gatterman
>BDC reacts with Cu + HX(X=cl,br) to give ➡️ haloarene
3.BDC when heated in presence of HBF4 give ➡️fluorobenzene(haloarene)
4.BDC when heated in presence of KI give ➡️ iodobenzene (haloarene)

Question 18

Physical properties of haloalkanes/arenes?

Answer 18

1.Melting point is directly proportional to symmetry

2. Boiling points {directly proportional to Vander waal forces} and {directly proportional to molecular mass} and {inversely proportional to branching}

3.Order of BP in haloarenes is :
O>p>m

4.Order of mp in haloarenes is :
P>o>m

Question 19

Physical property ➡️ solubility

Answer 19

Halokanes are less soluble in water as the energy released after the formation of new H bond isn’t much and so these new bonds are not strong between haloalkane molecule and water molecules leading to less or no solubility at all.

Question 20

Name the Chemical properties of haloalkanes and arenes ?

Answer 20

1. Nucleophilic substitution rxn
2. Elimination rxn
3. Rxn with metals

Question 21

Two types of Nu-substitution rxn ?

Answer 21

SN1 and SN2

Question 22

SN1

Answer 22

when the two products are formed it is known as resmic mixture.

Two step process
Decreasing stability order or reactivity order {3°>2°>1°}

[1 step] carbocation formation
RX placed in polar protic solvent (H2O) breaks X bond to form a carbocation.

[2 step] attack of nu-
As carbocation is formed i.e C acquires +ve charge nu- attches itself to the carbon forming product.

Attachment of nu- is in two ways
it attaches from right a similar product as of reactant known as retained product is obtained
and the nu- attaches itself from backside inverted product is formed.

Question 23

SN2

Answer 23

alc. NaOH is not used here it is used in elimination rxn

Single step process
Decreasing stability order or reactivity order {1°>2°>3°}

RX in presence of aq. NaOH reacts in [polar aprotic solvent]
OH is a strong nu-
An intermediary step occurs ➡️ attack of OH grp and leaving of X takes place simultaneously where C shows pentvalency (unstable)
As X leaves and nu- is attached from the backside inverted product is formed

Question 24

Mohrs salt formula (double salt)

Answer 24

FeSO4.(NH4)2SO4.6H2O