Alkanes Flashcards
Methane Cannot be prepared by which 4 methods?
Wurtz Reaction, Sabatier-Senderen’s reaction, Kolbe’s reaction, Frankland’s Reaction
Reactivity order of halogens? Which halogen doesn’t given formation of alkanes from alkyl halides
Fluorine>Iodides> Bromides> Chlorides. Florine doesn’t show due to strong bond showing low dissociation
Give Wurtz Reaction
Ch3Br + 2na + brch3 GIVES{DRY ETHER} ch3-ch3 + 2nabr
(A)Reactions that give only symmetrical alkanes .(B)Which one give unsymmetrical as well as symmetrical?
(A)Wurtz, (B) Corey House
(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)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
Write Kobe’s Electrolytic method.
2CH3COOH-NA+ + 2H2O GIVES{ELECTROLYSIS} CH3CH3 + 2CO2 + H2 + 2NAOH
2 Reaction which transforms aldehydes and ketones to alkanes? Also give it’s catalysts.
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.
Catalyst in Frankland’s reaction? Also give its rn
Ether which is an inert solvent
General formula of Grignard reactions. Catalysts?
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
Does eicosane or decane have higher MP?
Decane(C10H22) has higher MP than Eicosane(C20H42)
Why do alkanes show low reactivity towards acids, bases, oxidizing and reducing agents?
Non polar nature and absence of pi bond
Halogenation Conditions:
High temp(300C to 500C) or in presence of Sunlight or UV rays. The extent of halogenation depends on amount of halogen used
Halogens that have special cases when doing halogenation reaction for alkanes.
Fluor9nes react violently while Iodination is very slow and reversible and so iodination is carried out in presence of oxidizing agent of HIO3.
When incomplete combustion(Insufficient amount of air) of alkanes occur, what is formed? What is it’s uses?
Carbon black. Used for manufacture of ink, printer ink, black pigments and filters
Molecular formula of Iodic acid
HIO3
Methanol other names
Carbinol and wood spirit
Conditions for aromatization?
773K, 10-20atm,presence of oxides of vanadium, molybdenum or chromium. The excess H formed when double bonds are formed anre releases out
Conditions for isomerisation?
Anhyd ALCL3/HCL
What is cracking?
Pyrolysis
When methane and dioxygen is passed over molybdenum oxide, what is obtained and what conditions are needed?
543K and 100atm. Methanal is obtained.
Alkanes except methane when react with manganese acetate form?
Carboxylic acids
Alkanes reacting with pottasium permanganate has products?
No products as alkanes resist oxidation. Only tertiary alkanes having tertiary H atom can oxidised to from alcohols
BR-MG-CH3 + HOC2H5 Gives what? Also what reaction is this and which catalyst is required for such reactions?
CH3-H +Mg(BROCH3) where mg has bonds with Br and OCH3. This reaction happens in presence of acid containing an active H+.
What is role Lialh4?
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
Stability order of cyclo alkanes
Cyclo pentane >Cyclo butane > Cyclo propane. Since cyclo propane is most unstable, it is prone addition reactions
Which all reactions increase carbon by one? Which ones decrease one carbon?
(A) Wurtz, Corey house
(B) Soda lime decarboxylation
NH2NH2
Hydrazine
Hydrazine uses?
Reduction of aldehydes and ketones into hydrocarbons using hydrazine and sodium ethoxide is called Wolf Kishner Reduction
How to convert alkanes to Benzene/ Aromatic compounds?
Use catlyst Cr2O3/MMo2O3 , 773K, 10-20atm
Peculiarity of Vinyl and Aryl Halides?
They don’t give Friedel’s craft reaction
2 Methyl Butane on oxidation with KMNO4
2 Methyl Butan-2-ol
