OBC project by Kyaw Kyaw Thaung Myint /CBE

Aldehydes and Ketones

s102039262 — 2021-07-03 06:56:39 UTC

Organic compounds who have a carbonyl group(C=O). The functional group of an aldehyde consist of carbon, hydrogen and an alkyl group. The functional group of a ketone consist of 2 different alkyl groups flanking an oxygen molecule.

experiment to identify ketones and aldehydes. (similar to benedict & fehling: cu(ii) ions and tollen test: agno3. (all the strong OA)

2021-07-03 07:23:37 UTC

- acidified potassium dichromate
presence of aldehydes will change the solution from orange to green. ( this is due to the reduction of orange dichromate(vi) ions to green chronium (iii) ions. the aldehyde is then oxidised to become carboxylic acid. )
1/2 : Cr2O2−7+14H++6e−→2Cr3++7H2O(3)
1/2 : RCHO+H2O→RCOOH+2H++2e−
final 2RCHO+Cr2O2−7+8H+→3RCOOH+2Cr3++4H2O

reactions of aldehydes/ketones

2021-07-03 07:39:18 UTC

hydration( forming of hydrates):
1. formaldehyde+H2O > hydrate(2 OH, 2 H)
2. acetone+H2O < hydrate (2 OH, 2 R)
3.acetaldehyde+ H2O > hydrate (2 OH, 1 H, 1 R)

oxidation of aldehydes and ketones

2021-07-03 08:21:23 UTC

oxidation (forming of hemiacetals and hemiketals):
hemiacetals (RH)
1. aldehyde/ketone +OH < hemiacetal (1 R, 1 H, 1 R"O, 1 OH)
2. aldehyde&OH(oxo alcohol) +OH > cyclic hemiacetal

Preparation of aldehydes

s10203897 — 2021-07-03 08:34:06 UTC

Oxidation of primary alcohols
Partial reduction of esters

oxidation and reduction of ketones and aldehydes

2021-07-03 08:44:54 UTC

aldehydes are protonated because of the hydrogen hence making it easier for them to be oxidised.
ketones are more inert to oxidation reactions. however it can be oxidised still, but require certain conditons such as a strong OA (H2O, hot alkaline KMnO4, NaOH). the strong oxidising agent breaks the c=c bond into 2 cooh

References

s10203897 — 2021-07-03 09:12:11 UTC

Khan academy (n.d.) Unit: Aldehydes and Ketones https://www.khanacademy.org/science/organic-chemistry/aldehydes-ketones

Jim C (2020) Oxidation of Aldehydes and Ketones
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Aldehydes_and_Ketones/Reactivity_of_Aldehydes_and_Ketones/Oxidation_of_Aldehydes_and_Ketones

McMurry: Organic Chemistry, 9th edition. Aldehydes and Ketones https://ng.cengage.com/static/nb/ui/evo/index.html?eISBN=9781305084414&id=37380118&snapshotId=136806&

Anon, 2019. Interesting Aldehydes and Ketones
https://chem.libretexts.org/@go/page/30581

Anon, 2020. Properties of Aldehydes and Ketones
https://chem.libretexts.org/@go/page/16050

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further oxidation of aldehydes and ketones.

2021-07-03 09:57:11 UTC

upon first oxidation of aldehydes, it will give a hydrate. when hydrates are further oxidised, the end result would give a carboxylic acid.
-for benzaldehydes, first oxidation with cyanide ion will turn it into a tetrahedral intermediate that is protonated by hydrogen cyanide to give a cyanohydrin product plus regenerated cyanide ion.

2021-07-03 10:00:11 UTC

Oxidation of primary alcohols using DMP gives aldehyde

s102039262 — 2021-07-03 10:03:41 UTC

The reaction is often carried out using the Dess–Martin periodinane reagent in dichloromethane solvent at room temperature:

Partial reduction of an ester using diisobutylaluminum hydride (DIBAH, or DIBAL-H) gives aldehyde

s102039262 — 2021-07-03 10:04:15 UTC

Important laboratory-scale method of aldehyde synthesis, and mechanistically related processes also occur in biological pathways. The reaction is normally carried out at (dry-ice temperature, -78^oC in toluene solution.

2021-07-03 10:09:31 UTC

s102039262 — 2021-07-03 10:25:20 UTC

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s102039262 — 2021-07-03 10:46:14 UTC

isomerism of ketones and aldehydes

2021-07-03 17:09:47 UTC

=positional, chain, geometric
Condensations of cyanoacetate with aliphatic and aromatic aldehydes give (E)-product

E isomers: the higher priority groups are on opposite sides of the double bond.
Z isomers: the higher priority groups are on the same side of the double bond.

fun facts

2021-07-04 03:24:28 UTC

aldehydes and ketones are seen very commonly in nature. they are usually bonded with other functional groups.
- ketones specifically are found in human bodies.
they show up in many important hormones such as progesterone (a female sex hormone) and testosterone (a male sex hormone)
The ketone functionality also shows up in the anti-inflammatory steroid, Cortison.
this shows how subtle differences in structure can cause drastic changes in biological activity.
-aldehydes and ketones are famous for its fragrance and odors, specifically the scent they produce.
eg: formaldehydes: disinfectant
benzaldehyde: almond oil
heptanone: blue cheese

solubility due to polarity of aldehydes and ketones

2021-07-04 03:29:31 UTC

Due to the polarity of the carbonyl group, the oxygen atom of the aldehyde or ketone engages in hydrogen bonding with a water molecule.

The solubility of aldehydes and ketones are therefore about the same as that of alcohols and ethers. Formaldehyde (HCHO), acetaldehyde (CH3CHO), and acetone ((CH3)2CO) are soluble in water. As the carbon chain increases in length, solubility in water decreases.

2021-07-04 03:40:27 UTC

progesterone

s102224381 — 2021-07-04 05:21:50 UTC

female sex hormone

testosterone

s102224381 — 2021-07-04 05:22:14 UTC

male sex hormone

s102224381 — 2021-07-04 05:24:02 UTC

s102224381 — 2021-07-04 05:38:36 UTC