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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Solero on May 19, 2020, 04:14:43 AM

Title: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: Solero on May 19, 2020, 04:14:43 AM

Does someone have experience with the chlorination of vinylacetate to make chloroacetaldehyde?

One article mentions that this reaction is better carried out in two steps. Chlorine is first added to vinylacetate at room temperature with cooling to form 1,2-dichlororethylacetate, which is then hydrolyzed at 50-60°C to form chloroacetaldehyde.

Can someone explain me this two steps reaction?
Do you make HCL in step 1?
In step 2 you make besides chloroacetaldehyde also acetic acid and HCL?

Thanks

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: AWK on May 19, 2020, 05:16:11 AM

Could you try to write reactions in both stages of the synthesis. Then everything will become clear.

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: kriggy on May 19, 2020, 05:17:05 AM

Isnt it better to just buy chloroacetaldehyde from sigma? Its not exactly expensive

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: Solero on May 19, 2020, 06:00:08 AM

It is not the purpose to buy chloroacetaldehyde, we need to make it from vinylacetate.

Step 1: Vinylacetate + Chlorine --> 1,2-dichlororethylacetate
Step 2: 1,2-dichlororethylacetate + H-OH --> chloroacetaldehyde

I do not understand how you can do it in two steps? For the hydrolysis you need and acid but is there HCL formed in step 1? They do not mention to add acid during step 2.
Do you not need to add water + vinylacetate and then chlorine?

I want to add the chemdraw picture from the reactions above but I do not know how to add it in this post.

Regards

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: AWK on May 19, 2020, 07:04:14 AM

Verbally finished recording chemical reactions around 1860. At that time, they were able to present chemical reactions with summary formulas and began thinking about reaction mechanisms. Use structural or at least semi-structural formulas, eg.
CH₂=CH-O-CO-CH₃ + ...

This reaction is usually carried out in ethanol to give immediately diethyl acetal in good yield. The acetal can always be easily hydrolyzed to give aldehyde. Search for old patents.

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: Solero on May 19, 2020, 07:25:38 AM

Thanks

I do need to have chloroacetaldehyde to react it further with thiourea to form 2-aminothiazole.HCL

Title: Re: Chlorination of vinylacetate to form Chloroacetaldehyde
Post by: AWK on May 19, 2020, 08:12:14 AM

Depending on what you want to get next, acetal can be even more useful. In addition, it is more durable and can be stored longer. The aldehyde group can be easily unblocked before the reaction. Just diethyl chloroacetal is a very good reagent for the synthesis of aminothiazole.