The general methods of preparation for aliphatic hydrocarbons include several key techniques. Alkanes can be synthesized through hydrogenation of unsaturated hydrocarbons, such as alkenes and alkynes, using catalysts like nickel, palladium, or platinum under specific temperature conditions. Another method involves the reaction of alkyl halides with zinc in the presence of an acid, which leads to the formation of alkanes. Additionally, alkanes can be produced via decarboxylation of monocarboxylic acids when their sodium salts are heated with soda-lime, or through Kolbe's electrolytic method, which generates symmetrical alkanes from the electrolysis of sodium or potassium salts of carboxylic acids. These methods highlight the versatility in synthesizing various aliphatic hydrocarbons
What is the general method for preparing alkanes from alkenes?
Alkanes can be prepared from alkenes through catalytic hydrogenation, where alkenes react with hydrogen in the presence of a catalyst like nickel, palladium, or platinum at elevated temperatures
How can alkynes be synthesized from vicinal dihalides?
Alkynes can be synthesized by the dehydrohalogenation of vicinal dihalides using a strong base, which eliminates two molecules of hydrogen halides from adjacent carbon atoms
What role does zinc play in the preparation of alkanes?
Zinc is used in the reaction of alkyl halides with an aqueous acid to produce alkanes, facilitating the reduction of the halide
Describe the Kolbe's electrolytic method for preparing alkanes.
Kolbe's electrolytic method involves the electrolysis of sodium or potassium salts of carboxylic acids, which leads to the formation of symmetrical alkanes
What is the significance of the Sabatier-Senderens reaction in hydrocarbon preparation?
The Sabatier-Senderens reaction is significant for the hydrogenation of unsaturated hydrocarbons, allowing for the conversion of alkenes and alkynes into alkanes, which is important in both laboratory and industrial applications
Which of the following methods is used to prepare alkanes from alkenes?
a) Dehydrohalogenation
b) Hydrogenation
c) Halogenation
d) Nitration
Answer: b) Hydrogenation
In Kolbe's electrolytic method, which compounds are electrolyzed to produce alkanes?
a) Alcohols
b) Carboxylic acid salts
c) Alkenes
d) Alkyl halides
Answer: b) Carboxylic acid salts
What is the primary catalyst used in the hydrogenation of alkenes?
a) Iron
b) Nickel
c) Copper
d) Zinc
Answer: b) Nickel
Which reaction involves the elimination of water from alcohols to form alkenes?
a) Hydrogenation
b) Dehydration
c) Halogenation
d) Nitration
Answer: b) Dehydration
What is the product of the reaction between an alkyl halide and zinc in the presence of an acid?
a) Alkene
b) Alkyne
c) Alkane
d) Alcohol
Answer: c) Alkane