Are sulfonate esters good leaving groups?

Summary. It is not favourable for alcohols to undergo elimination and nucleophilic substitution reactions, because hydroxyl groups are poor leaving groups. However, alcohols can be made to undergo these reactions by converting them into sulfonate esters, which are much better leaving groups.

Why is sulfonate a good leaving group?

Triflate, tosylate, and mesylate ions are excellent leaving groups, because the sulfonate ions can stabilize the negative charge via resonance. Good leaving groups are weak bases. These ions are weak bases because they are the conjugate bases of very strong sulfonic acids.

Which leaving group is known as good leaving group?

Weak Bases are the Best Leaving Groups A strong bases wants to donate electrons; therefore, the leaving group must be a weak base.

What is the leaving group in esterification?

In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters such as tosylate (TsO−).

Why are sulfonate esters a good leaving group?

Protonating a hydroxyl group makes it into a far better leaving group (water is a weak base). Another way that alcohols can be made into good leaving groups is by converting them into sulfonate esters. Similar to the relationship between (carboxylic acid) esters and carboxylic acids, sulfonic esters are derivatives of sulfonic acids.

What kind of bond does a sulfonate ester have?

Sulfonate esters contain a sulfur with two double bonds to oxygen, a single bond to an R group, and a single bond to an OR group (where the R groups are usually alkyl or aryl groups).

How to make sulfonate ester from methyl alcohol?

3. The product from Step 2 (15.4 mmol) was added to a solution of paratoluenesulfonic acid monohydrate (0.25 g in 37.5 ml ethyl alcohol), refluxed 6 hours, then cooled. The resulting white solid was re-crystallized from methyl alcohol/CH 2 Cl 2, 2:1, and the product isolated in 100% yield. 1 H- and 13 C-NMR data supplied.

How is sulfonate ester converted to a ketone?

The intermediate trienes often cannot be isolated as the cycloaddition is so facile. Further functionalization is possible by conversion of the sulfonyl group into a ketone by oxidative desulfurization via the α-borinate, the vinyl sulfonate ester then acting as a masked ketone <89AG (E)202, 92SL985, 93SL399 >.

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