4.1.2- Carbonyl Compounds Flashcards
What observation is seen by acidified dichromate ions
Orange to Green
What oxidising agent is used in the preparation of carbonyls?
Acidified dichromate ions (eg mix of K2Cr2O7 and H2SO4), denoted [O]
State the condition for oxidising primary alcohol to aldehyde
Distil the product/aldehyde immediately to prevent further oxidation
State the condition for oxidising primary alcohol to carboxylic acid
Heat under Reflux (continual boiling and condensing of reaction mixture to make sure reaction takes place without the contents of the flask boiling dry)
What reducing agent is used in the reduction of carbonyls?
NaBH4 (sodium borohydride)
What reaction is used for the reduction of carbonyls
Nucleophilic addition
What is a nucleophile
An atom or group of atoms attracted to an electron deficient centre, where it donates a pair of electrons, to form a covalent bond
What is the chemical test for an aldehyde/Ketone and it’s observation
2,4-DNPH, orange precipitate. (Sometimes called Brady’s reagent)
How do you identify the specific carbonyl compound
The precipitate from the test with 2,4-DNPH is a 2,4-DNPH derivative, filter it off and recrystallise to purify it, determine it’s melting point and compare against known values in a data book.
What is the chemical test for distinguishing between aldehydes and ketones and it’s observation. (Also, how does it work)
Tollens’ reagent, silver mirror/silver solid with aldehydes.
This works as Tollens’s reagent is a week oxidising agent and since only aldehydes can be oxidised further, only they can reduce the silver Ines to silver metal producing the positive observation.
