Experiments of Carbonyl Compounds Flashcards
Generally referred to as derivatives of water:
alcohol
ether
phenol
readily donates the H bonded to O in the presence of a strong base or Na and K metal making them slightly acidic.
alcohol and phenol
more acidic than alcohol due to the resonance structures of phenoxide ion
phenol
can be classified as primary, secondary and tertiary .
alcohol
has a general formula R-O-R, is less reactive compared to alcohol and phenol
ether
show the general formula of aldehyde and keton
grade yourself accordingly
draw the general formula of types of alcohol
grade yourself accordingly
are characterized by the presence of the carbonyl group -C=O
aldehyde and ketone
Both are polar compounds which explain their relatively higher melting and boiling points compared with hydrocarbons of comparable molecular weight
aldehyde and ketone
Because of their polarity, these are both fairly soluble in water
aldehyde and ketone
test for the presence of aldehydes and ketones wherein both produce yellow crystalline derivatives
2,4-dinitrophenylhydrazine test
can be used to differentiate between aldehydes and ketones
oxidation reactions
are easily oxidized compared to ketones
aldehydes
resistant to oxidation
ketones
commonly used to determine the presence of aldehydes. The test uses silver nitrate and ammonia in water
Tollen’s test
containing methyl group attached to the carbonyl carbon can be determined using the iodoform test.
ketones
test used in experiments of carbonyl compounds
2,4-DNP
Tollen’s test
Iodoform Test
Jones Test
samples to be tested
Benzaldehyde
Acetone
Acetaldehyde
Formaldehyde
2-propanol
2-pentanone
3-pentanone
Cyclohexanone (not done in the video)
reagents used
Tollen’s reagent
10% NaOH
2,4-dinitrophenylhydrazine
95% ethanol
I2 / KI solution
Chromic acid reagent
equipment needed
test tubes
pasteur pipettes
10mL graduated cylinder
procedure for dinitrophenylhydrazine test
add 2 mL of ethanol to each test tube
add 5 drops of acetone to first test tube
add 5 drops of benzaldehyde to the second test tube
add 2 mL of 2,4-dinitrophenylhydrazine
shake and observe
- Tollen’s test procedure
Place 5 mL (3mL) Tollen’s reagent in each test tube
Add 3-4 drops of formaldehyde to the first test tube, observe
Add 3-4 drops of Benzaldehyde to the second test tube, observe
Add 3-4 drops of acetone to third test tube, observe
If there’s no reaction, place test tubes in hot water bath for two minutes
iodoform test procedures
Add 3 mL of 5% sodium hydroxide to each of the four test tubes
Add 10 drops of acetone to the first test tubes
Add 10 drops of 2-propanol to the second test tube
Add 10 drops of 2-pentanone to the third test tube
Add 10 drops of 3-pentanon to the third test tube
Add about 10 mL of iodine solution to each test tube and shake
jones/chromic acid test
Place 1 mL acetaldehyde in a clean dry test tube
Add 4-5 drops of chromic acid solution agitating the test tube with each addition
Let stand for 10 minutes
2,4 DNP result in Benzaldehyde and Acetone
All positive
Tollens test result for Benzaldehyde, Acetone, and Formaldehyde
Benzaldehyde +
Acetone -
Formaldehyde +
Iodoform test for Acetone, 2-propanol, 2-pentanone, 3-pentanone
Acetone +
2-propanol +
2-pentanone +
3-pentanone -
Results in 2,4-diphenylhydrazine test:
Benzaldehyde – positive
Acetone – positive
used to identify the presence of carbonyl functional groups in organic compounds.
2,4-DNP test
Detects aldehydes and ketones
2,4-DNP test
precipitate formed in 2,4-DNP test when it is positive, confirming the presence of a carbonyl group
dinitrophenylhydrazone
added to the mixture of 2,4-DNP and the compound to be tested
mild acid
Results in Tollen’s test:
Benzaldehyde – negative (should be positive)
Acetone – negative
Formaldehyde – positive
is a chemical test used to detect the presence of aldehydes in a given compound. It is named after its developer, Bernhard Tollens
tollen’s test
if this is present, the mixture will undergo oxidation in the presence of Tollens’ reagent. This oxidation reaction converts the aldehyde to a carboxylic acid while simultaneously reducing the silver ions to metallic silver.
aldehyde
what the aldehyde will turn into with the Tollen’s reagent
carboxylic acid
do not give a positive Tollen’s test because they lack the active hydrogen atom required for the oxidation process.
ketones
Iodoform test results:
Acetone – negative (should be positive)
2-propanol – positive (should be positive)
2-pentanone – negative (should be positive)
3-pentanone – negative
used to identify compounds containing the CH3CO- (acetyl) group or compounds that can be oxidized to produce acetyl groups
iodoform test
A small molecule made of two carbon, three hydrogen, and one oxygen atoms
acetyl group
used to detect the presence of primary and secondary alcohols in a compound
Jones test
what’s the composition of the Jones reagent
Chromic acid
Jones reagent is prepared by dissolving this in aqueous sulfuric acid (H2SO4)
Chromium trioxide
process in the Jones test to corresponding aldehydes or ketones
oxidation
If these are present in the compound being tested, it will be oxidized by the Jones reagent.
primary and secondary
primary alcohols are oxidized to this in Jones test
aldehydes
secondary alcohols are oxidized to this in Jones test
ketones
do not undergo oxidation under Jones test
tertiary alcohol
ndicates a positive result in Jones test
green-colored complex
