Question

Ethyl orthoformate is formed by heating ________ with sodium ethoxide.
A. ${\text{CHC}}{{\text{l}}_3}$
B. ${{\text{C}}_2}{{\text{H}}_5}{\text{OH}}$
C. ${\text{HCOOH}}$
D. ${\text{C}}{{\text{H}}_2}{\text{CHO}}$

Answer 1

Hint: The chemical formula of ethyl orthoformate is ${\text{CH(O}}{{\text{C}}_2}{{\text{H}}_5}{{\text{)}}_3}$ and the chemical formula of sodium ethoxide is ${{\text{C}}_2}{{\text{H}}_5}{\text{ONa}}$. Remember that in the formation of Ethyl orthoformate the role of leaving the group is important. The better the leaving group, the more stable the product will be.

Complete step-by-step answer:
The reaction is a simple substitution reaction under some amount of heat.
Sodium ethoxide is formed by reacting sodium metal or sodium hydroxide with ethyl alcohol (ethanol), this reaction gives a liquid state of sodium ethoxide.
Now, it is evident from the question that we need two reactants for the formation of Ethyl orthoformate. One is sodium ethoxide and to get an idea of the reactant we have to search for the best leaving group among the given option,
Almost all the options have oxygen in them, now understand that we have oxygen in sodium ethoxide too, this oxygen will attack the other reactant in presence of heat, and form ethyl orthoformate.
The presence of oxygen in the other reactant does not favor the reaction, and the only option without oxygen is chloroform (${\text{CHC}}{{\text{l}}_3}$), also chlorine will act as a good leaving group by forming NaCl as the byproduct.
The reaction for the following can be written as:
${\text{3}}{{\text{C}}_2}{{\text{H}}_5}{\text{ONa }} + \,{\text{ CHC}}{{\text{l}}_3}\xrightarrow{\Delta }{\text{ CH(O}}{{\text{C}}_2}{{\text{H}}_5}{{\text{)}}_3} + {\text{ 3NaCl}}$

Hence, the correct answer is option (A) i.e., ${\text{CHC}}{{\text{l}}_3}$

Note: Ethyl orthoformate is often called triethyl orthoformate, because of the presence of 3-ethyl group ( -${{\text{C}}_2}{{\text{H}}_5}$) both names are completely valid and accepted, hence avoid confusion in the same. Also, the process of formation of sodium ethoxide given in the solution is not the only method used, for e.g., we can sodium ethoxide by reacting anhydrous ethanol with sodium hydroxide.