All GRE Subject Test: Chemistry Resources
Example Question #24 : Reactions By Product
Which of the following reactions would NOT produce a carboxylic acid?
PCC is considered a weak oxidizing agent. The reaction of a primary alcohol with PCC would only yield an aldehyde, while reaction with a secondary alcohol will yield a ketone. PCC will not be used to generate carboxylic acids.
A stronger oxidation, like or , is required to oxidize up to the carboxylic acid. Treatment of an ester with a base or treatment of carbon dioxide with a Grignard reagent are other ways of making carboxylic acids.
Example Question #25 : Reactions By Product
Which one of the following compounds can produce a carboxylic acid only when reacted with sodium dichromate and sulfuric acid?
After recognizing the reagents given, we know we need to begin with an alcohol. The alcohol choices differ only by how substituted they are.
For a carboxylic acid to form from a reaction with sodium dichromate and sulfuric acid, a primary alcohol needs to be available. Therefore, 1-pentanol is the correct answer.
Example Question #3 : Carboxylic Acid Chemistry
When 3-chloroheptane undergoes malonic ester synthesis, the final product is __________.
a ten-carbon ketone
None of the other answers
The malonic ester is deprotonated at the most acidic hydrogen, the one on the carbon between the two oxygens. The electrons from that bond to the hydrogen form a carbon-carbon double bond while electrons from the oxygen-carbon double bond go to the oxygen atom. This is the enolate form. The chlorine leaves the 3-chloroheptane and the electrons from the carbon-carbon double bond bond to the carbon that the chlorine left. At the same time, the carbonyl is reformed. After deesterfication, 3-ethylheptanoic acid is formed.