alkyne Flashcards

1
Q

NaNH2, R-MgX, LDA, NH2-

dbond given

A

anti elimnation and forms alkyne (tb)

strong base take away from anti sides

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2
Q

alc KOH/ heat

gmp of alkyne, nh2- added afterwards @geminal

A

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-

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3
Q

triple bond in cyclic(benzenes)
yes/no

A

not possible

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4
Q

tri halo derivativeof CH3

A

The halo form- CH3-X

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5
Q

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

A

CH3-I test forms yellow ppt

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6
Q

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

A

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

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7
Q

How to form Higher alkyne

A
  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’
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8
Q

Which metal carbide forms ethyne?

A

CaC2 + H2O—> Ca(OH)2 + c(tb)c

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9
Q

Which metal carbide is used to from propyne?

A

Mg2C3 +H2O–> Mg(OH)2 + c-c(tb)c

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10
Q

By which method only ethyne can be prepaired?

A

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

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11
Q

Alkynes are odourless, except for?

A

Ethyne

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12
Q

Test of alkyne with Br2/H2O

A

reddish brown

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13
Q

Test of alkyne with alk. KMno4(baeyers solution)

A

Purple pink

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14
Q

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

A

white ppt

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15
Q

Ammonical cuprous chloride gves alkyne test

A

( 2CuCl4+ 2 NH4OH)
Red ppt

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16
Q

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

e+ addition

A

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)

17
Q

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

A

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

18
Q

Cl2, chlorine+ H20
(halogen-ine)

A

X2/H2O
X+ & OH-

19
Q

R-C(tb)CH + H2SO4/HgSO4

A

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

KUCHEROV Reaction

20
Q

HBO on Alkyne

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

H2O2 also used

A

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

21
Q

R- C(TB)-R’

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

oxidation of alkyne

A
  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
22
Q

R-C(tb)C-C —NaNH2/heat—> ??

R-C(tb)C-C <—???

A

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

ISOMERISATION

23
Q

A-NH2 in liq NH3 +Alkyne
NaNH2/ LiNH2

A

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

24
Q

Cu tube + Alkyne
* ethyne
* propyne

A

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

polymerization