alkyne

Question 1

NaNH2, R-MgX, LDA, NH2-

dbond given

Answer 1

anti elimnation and forms alkyne (tb)

strong base take away from anti sides

Question 2

alc KOH/ heat

gmp of alkyne, nh2- added afterwards @geminal

Answer 2

double bond formation structure chosen where anti elimantion is possible

Pehle X(1) Alc KOH leke jayega and then X(2) ko strong base NH2-

Question 3

triple bond in cyclic(benzenes)
yes/no

Answer 3

not possible

Question 4

tri halo derivativeof CH3

Answer 4

The halo form- CH3-X

Question 5

CH3-(C=O)-
Acetyl gives which test

Answer 5

CH3-I test forms yellow ppt

Question 6

GMP of triple bond,, by terta halides
-(X2)C-C(X2). Reagent used?

Answer 6

2(Zn) is used to eliminate 4X to form 2(ZnX2)

Question 7

How to form Higher alkyne

Answer 7

1. take a tb
2. add base (oh-/nh2-)
3. Take out H2O to form carboanion R-C(tb)C(-)
4. Add R’-X where R’ is 1’ or 2’

Question 8

Which metal carbide forms ethyne?

Answer 8

CaC2 + H2O—> Ca(OH)2 + c(tb)c

Question 9

Which metal carbide is used to from propyne?

Answer 9

Mg2C3 +H2O–> Mg(OH)2 + c-c(tb)c

Question 10

By which method only ethyne can be prepaired?

Answer 10

From
Graphite(solid) +H2–silent electric discharge–> C2H2

Question 11

Alkynes are odourless, except for?

Answer 11

Ethyne

Question 12

Test of alkyne with Br2/H2O

Answer 12

reddish brown

Question 13

Test of alkyne with alk. KMno4(baeyers solution)

Answer 13

Purple pink

Question 14

Ammonical Silver Nitrate( Tollen reagent) gives Alkyne(@terminal) test

Answer 14

white ppt

Question 15

Ammonical cuprous chloride gves alkyne test

Answer 15

( 2CuCl4+ 2 NH4OH)
Red ppt

Question 16

Alkyne+
1. HCL[H+CL-]
2. CH3COO- H+
3. H+CN-

e+ addition

Answer 16

Seperate H+ and add remaining to broken tb (+) side
* Cl addition in HCL on Double bond
more stable c+ –major (markonikov)
less stable c+ –minor(anti-markonikov)

Question 17

Alkyne
1. HBr/CCI4
2. Br2/CCI4
3. I2/CCl4

Answer 17

2moles of each used to reduce the tb to single bond
1. [H+ & Br-] syn add (br-br @ geminal)
2. [Br- & Br+] anti add to avoid steric hinderance (4Br)
3. 1 mole of I2 used since in the third step due to large I size steric hinderance will be observed

Question 18

Cl2, chlorine+ H20
(halogen-ine)

Answer 18

X2/H2O
X+ & OH-

Question 19

R-C(tb)CH + H2SO4/HgSO4

Answer 19

Acetyl
[enol –> keto] R-(Me)-C=O
(triple bond breaks to single bond and =o is added to C+)

KUCHEROV Reaction

Question 20

HBO on Alkyne

B2H6[BH2+ & H-] / ** HF**

H2O2 also used

Answer 20

*terminal *alkyne–>aldehyde keto form
Tb breaks to form single bond and =O is added to terminal C(anti markonikov)

Question 21

R- C(TB)-R’

1.cold alk.KMnO4
2.+ glyoxal
3.hot KMnO4

oxidation of alkyne

Answer 21

1. 2mole of KMnO4
   R-(O=C-C=0)-R
2. RO-(O=C-C=O)-OR
3. Carboxylic acid[ R-(O=)C-OH] + R’COOH

Question 22

R-C(tb)C-C —NaNH2/heat—> ??

R-C(tb)C-C <—?—??

Answer 22

??-R-C-C(tb)C
?- alc KOH/heat

ISOMERISATION

Question 23

A-NH2 in liq NH3 +Alkyne
NaNH2/ LiNH2

Answer 23

R-C-C(tb)C-A+
* C-C(tb)C(-ve)Na+
* C-C(tb)C(-ve)Li+

Question 24

Cu tube + Alkyne
* ethyne
* propyne

Answer 24

cyclic
* benzene
* 1,3,5, trimethyl benzene (mesitylene)

polymerization