Q.65. Given below are two statements : Statement-I : Methane can be prepared by decarboxylation of sodium ethanoate, Kolbe's electrolysis of sodium acetate and reaction of CHMgBr with water. Statement

Question

Q.65. Given below are two statements : Statement-I : Methane can be prepared by decarboxylation of sodium ethanoate, Kolbe's electrolysis of sodium acetate and reaction of CHMgBr with water. Statement-II: Methane cannot be prepared from unsaturated hydrocarbons and by Wurtz reaction. In the light of the above statements, choose the correct answer from the options given below.

FirstInTest · Accepted Answer

Correct answer: D. Statement-I: Methane can be prepared by decarboxylation of sodium ethanoate (soda lime decarboxylation) and by the reaction of CH$_3$MgBr (Grignard reagent) with water. However, Kolbe's electrolysis of sodium acetate (sodium ethanoate) yields ethane (CH$_3$-CH$_3$), not methane. Therefore, Statement-I is false.

Statement-II: Methane cannot be prepared from unsaturated hydrocarbons (alkenes/alkynes) by hydrogenation to form methane (it would form higher alkanes if starting from higher unsaturated hydrocarbons, or ethane from ethene, etc.). Also, the Wurtz reaction (2RX + 2Na $\rightarrow$ R-R + 2NaX) forms alkanes with an even number of carbon atoms by coupling two alkyl halides. If R is methyl (CH$_3$), it would form ethane (CH$_3$-CH$_3$), not methane. Therefore, Statement-II is true.

Thus, Statement-I is false but Statement-II is true.

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