Alkanes Flashcards

1
Q

Methane Cannot be prepared by which 4 methods?

A

Wurtz Reaction, Sabatier-Senderen’s reaction, Kolbe’s reaction, Frankland’s Reaction

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2
Q

Reactivity order of halogens? Which halogen doesn’t given formation of alkanes from alkyl halides

A

Fluorine>Iodides> Bromides> Chlorides. Florine doesn’t show due to strong bond showing low dissociation

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3
Q

Give Wurtz Reaction

A

Ch3Br + 2na + brch3 GIVES{DRY ETHER} ch3-ch3 + 2nabr

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4
Q

(A)Reactions that give only symmetrical alkanes .(B)Which one give unsymmetrical as well as symmetrical?

A

(A)Wurtz, (B) Corey House

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5
Q

(A)Name all catalysts involved un decarboxylation of carboxylic acids?
(B)Specialty of this reaction wrt to formed carbon compound?
(C) Another name for this reaction?

A

(A)NAOH, Cao to keep NAOH dry due to it’s hygroscopic nature, Heat
(B) Alkanes formed contain one carbon less than original
(C) Soda lime decarboxylation

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6
Q

Write Kobe’s Electrolytic method.

A

2CH3COOH-NA+ + 2H2O GIVES{ELECTROLYSIS} CH3CH3 + 2CO2 + H2 + 2NAOH

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7
Q

2 Reaction which transforms aldehydes and ketones to alkanes? Also give it’s catalysts.

A

Clemmensen Reduction and Woff kishner reduction. Amalgamated zinc-Hg and conc. HCL for Clemmesoon reduction. First step loses 1H2Oand second step C2H5ONA or NOAH and heat for Woff kishner and also hydrazine(Not catalyst)

Tip: Basically number of oxygen-carbon bonds broken, that much number of hydrogen will be added in it’s place.

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8
Q

Catalyst in Frankland’s reaction? Also give its rn

A

Ether which is an inert solvent

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9
Q

General formula of Grignard reactions. Catalysts?

A

R-Mg-X. Undergoes hydrolysis in presences of acid or reacts with ammonia(HNH2 or NH3), alcohols or amines having active hydrogen atom to give alkane corresponding to alkyl group of Grignard reagent

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10
Q

Does eicosane or decane have higher MP?

A

Decane(C10H22) has higher MP than Eicosane(C20H42)

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11
Q

Why do alkanes show low reactivity towards acids, bases, oxidizing and reducing agents?

A

Non polar nature and absence of pi bond

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12
Q

Halogenation Conditions:

A

High temp(300C to 500C) or in presence of Sunlight or UV rays. The extent of halogenation depends on amount of halogen used

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13
Q

Halogens that have special cases when doing halogenation reaction for alkanes.

A

Fluor9nes react violently while Iodination is very slow and reversible and so iodination is carried out in presence of oxidizing agent of HIO3.

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14
Q

When incomplete combustion(Insufficient amount of air) of alkanes occur, what is formed? What is it’s uses?

A

Carbon black. Used for manufacture of ink, printer ink, black pigments and filters

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15
Q

Molecular formula of Iodic acid

A

HIO3

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16
Q

Methanol other names

A

Carbinol and wood spirit

17
Q

Conditions for aromatization?

A

773K, 10-20atm,presence of oxides of vanadium, molybdenum or chromium. The excess H formed when double bonds are formed anre releases out

18
Q

Conditions for isomerisation?

A

Anhyd ALCL3/HCL

19
Q

What is cracking?

A

Pyrolysis

20
Q

When methane and dioxygen is passed over molybdenum oxide, what is obtained and what conditions are needed?

A

543K and 100atm. Methanal is obtained.

21
Q

Alkanes except methane when react with manganese acetate form?

A

Carboxylic acids

22
Q

Alkanes reacting with pottasium permanganate has products?

A

No products as alkanes resist oxidation. Only tertiary alkanes having tertiary H atom can oxidised to from alcohols

23
Q

BR-MG-CH3 + HOC2H5 Gives what? Also what reaction is this and which catalyst is required for such reactions?

A

CH3-H +Mg(BROCH3) where mg has bonds with Br and OCH3. This reaction happens in presence of acid containing an active H+.

24
Q

What is role Lialh4?

A

It is a very strong reducing agent. That means it can add hydrogen. It is used in halogenation reactions for adding hlH to alkanes to transform then into alkanes

25
Q

Stability order of cyclo alkanes

A

Cyclo pentane >Cyclo butane > Cyclo propane. Since cyclo propane is most unstable, it is prone addition reactions

26
Q

Which all reactions increase carbon by one? Which ones decrease one carbon?

A

(A) Wurtz, Corey house

(B) Soda lime decarboxylation

27
Q

NH2NH2

A

Hydrazine

28
Q

Hydrazine uses?

A

Reduction of aldehydes and ketones into hydrocarbons using hydrazine and sodium ethoxide is called Wolf Kishner Reduction

29
Q

How to convert alkanes to Benzene/ Aromatic compounds?

A

Use catlyst Cr2O3/MMo2O3 , 773K, 10-20atm

30
Q

Peculiarity of Vinyl and Aryl Halides?

A

They don’t give Friedel’s craft reaction

31
Q

2 Methyl Butane on oxidation with KMNO4

A

2 Methyl Butan-2-ol