However, as with any equilibrium process, the reaction can be driven in one direction by changing the concentration, pressure, temperature, or volume of the reagents. When the concentration of one of the reactants is increased, the equilibrium shifts in the direction that will decrease its concentration.
Thus, by increasing the concentration of one reactant, the equilibrium produces more of the product, thereby resulting in a higher yield of the ester product.
One common method utilized in organic chemistry labs is to provide an excess of one of the reagents, typically the alcohol. As mentioned earlier, Fisher esterification can utilize sulfuric acid as a catalyst. However, one of the other functions of sulfuric acid is to act as a dehydrating agent, sequestering water molecules away from the reaction.
This increases the yield of the ester formed. To learn more about our GDPR policies click here. If you want more info regarding data storage, please contact gdpr jove. Your access has now expired. Provide feedback to your librarian. If you have any questions, please do not hesitate to reach out to our customer success team. Login processing Esterification Reaction Esters are formed from an esterification reaction, with simple esters being formed through Fisher esterification.
If you want the mechanism for the reaction involving alcohols you can find it by following this link. The phenol mechanism is similar, although hindered by the interaction between the lone pair on the oxygen of the -OH group and the ring electrons. If you aren't sure about using this symbol for a benzene ring , you could follow this link to find out all about it.
It is likely to take you some time, though, and you may have to visit several other pages as well. It isn't particularly important in the context of the current page. All you need to know is that at each corner of the hexagon there is a carbon atom, together with a hydrogen atom apart from where the oxygen is attached. The -COCl group is attached directly to a benzene ring. It is much less reactive than simple acyl chlorides like ethanoyl chloride.
The phenol is first converted into the ionic compound sodium phenoxide sodium phenate by dissolving it in sodium hydroxide solution.
The phenoxide ion reacts more rapidly with benzoyl chloride than the original phenol does, but even so you have to shake it with benzoyl chloride for about 15 minutes. Solid phenyl benzoate is formed. This reaction can again be used to make esters from both alcohols and phenols. The reactions are slower than the corresponding reactions with acyl chlorides, and you usually need to warm the mixture.
In the case of a phenol, you can react the phenol with sodium hydroxide solution first, producing the more reactive phenoxide ion. There is a slow reaction at room temperature or faster on warming. There is no visible change in the colourless liquids, but a mixture of ethyl ethanoate and ethanoic acid is formed. The reaction with phenol is similar, but will be slower.
Phenyl ethanoate is formed together with ethanoic acid. This reaction isn't important itself, but a very similar reaction is involved in the manufacture of aspirin covered in detail on another page - link below. It works well because the ester has the lowest boiling point of anything present.
The ester is the only thing in the mixture which doesn't form hydrogen bonds, and so it has the weakest intermolecular forces. Larger esters tend to form more slowly. In these cases, it may be necessary to heat the reaction mixture under reflux for some time to produce an equilibrium mixture. The ester can be separated from the carboxylic acid, alcohol, water and sulfuric acid in the mixture by fractional distillation.
Jim Clark Chemguide. Making esters Esters are produced when carboxylic acids are heated with alcohols in the presence of an acid catalyst. The equation for the reaction between an acid RCOOH and an alcohol R'OH where R and R' can be the same or different is: So, for example, if you were making ethyl ethanoate from ethanoic acid and ethanol, the equation would be: Doing the reactions Carboxylic acids and alcohols are often warmed together in the presence of a few drops of concentrated sulfuric acid in order to observe the smell of the esters formed.
You would normally use small quantities of everything heated in a test tube stood in a hot water bath for a couple of minutes. However having some ball park of how long would be useful. Is it on the order of hrs, days, months, years? Go and check it yourself, after all. Chemistry is an experimental science. Show 2 more comments. Active Oldest Votes. Improve this answer. Add a comment. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
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