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Esterification

acid reaction esters acetic

Esterification is the chemical process for making esters, which are compounds of the chemical structure R-COOR', where R and R' are either alkyl or aryl groups. The most common method for preparing esters is to heat a carboxylic acid, R-CO-OH, with an alcohol, R'-OH, while removing the water that is formed. A mineral acid catalyst is usually needed to make the reaction occur at a useful rate.

Esters can also be formed by various other reactions. These include the reaction of an alcohol with an acid chloride (R-CO-Cl) or an anhydride (R-CO-O-COR'). Early studies into the chemical mechanism of esterification, concluded that the ester product (R-CO-OR') is the union of the acyl group (R-C=O-) from the acid, RCO-OH, with the alkoxide group (R'O-) from the alcohol, R'-OH rather than other possible combinations.

The chemical structure of the alcohol, the acid, and the acid catalyst used in the esterification reaction all effect its rate. Simple alcohols such as methanol (CH3OH) and ethanol (CH3CH2OH) react very fast because they are relatively small and contain no carbon atom sidechains that would hinder their reaction. These differing rates of reaction were first reported by Nikolay Menschutkin (1842-1907) in 1879-83. He also noted that simple acids such as acetic acid or vinegar (CH3CO2H) form esters very easily. The most common acid catalysts are hydrochloric acid, HCl, and sulfuric acid, H2SO4, because they are very strong acids. At the end of the esterification reaction, the acid catalyst has to be neutralized in order to isolate the product. German chemists, during World War II, developed solid acid catalysts or ion exchange resins for use in the manufacture of esters. These solid catalysts work well with acid sensitive esters because they can be separated from the product by filtration and therefore, the catalyst does not spend very much time in contact with the acid unstable product.

The esterification process has a broad spectrum of uses from the preparation of highly specialized esters in the chemical laboratory to the production of millions of tons of commercial ester products. These commercial compounds are manufactured by either a batch or a continuous synthetic process. The batch procedure involves a single pot reactor that is filled with the acid and alcohol reactants. The acid catalyst is added and the water removed as the reaction proceeds. This method is most often used by chemists in the laboratory, but in a few cases, it is used by industry to make large quantities of esters. This batch process usually requires reactors that hold extremely large volumes of reactants. Butyl acetate is commonly prepared from butanol and acetic acid by this method. The continuous process for making esters was first patented in 1921 and has been used extensively in the manufacture of large quantities of esters. This procedure involves the mixing of streams of the reactants into a reaction chamber while the product is removed at the same time. Continuous esterification has the advantage that larger quantities of products can be prepared in shorter periods of time. This procedure can be run for days or weeks without interruption, but requires special equipment and special chemical engineering considerations. The continuous esterification process is used industrially to make methyl acetate from acetic acid and methanol and ethyl acetate from acetic acid and ethanol.

The alternative process of making esters from the reaction of an alcohol with an anhydride is important in the manufacture of drugs. This reaction gives an acid as a by-product.

Acetic anhydride, CH3-CO-O-CO-CH3, a derivative of acetic acid, the acid in vinegar, is the most commonly used anhydride reactant. Phenyl acetate, one ester prepared industrially by this method, is an important intermediate in the synthesis of acetaminophen. Aspirin, or acetylsalicylic acid, is also prepared in large scale by the esterification reaction of an alcohol with acetic anhydride. This anhydride is important in the production of cellulose acetate by the esterification of cellulose or cotton. Cellulose acetate was first prepared in 1865 and was used extensively during World War I to coat airplane wings. Today, cellulose acetate finds its largest application as the fibrous material used in cigarette filters. It is also used in various yarns and textiles and to make the tips of felt-tip pens. Phthalic anhydride, an anhydride derivative of a benzene or phenyl ring, yields dimethyl phthalate when reacted with methanol in a reaction to that described for acetic anhydride. Dimethyl phthalate is used as a mosquito repellent and in the manufacture of certain polyesters. It is also a component in hair sprays and is added to plastics to soften them.

See also Carboxylic acids.

Resources

Books

Kirk-Othmer Encyclopedia of Chemical Technology. New York: Wiley, 1991.

Loudon, G. Mark. Organic Chemistry. Oxford: Oxford University Press, 2002.

Patai, S., ed. Synthesis of Carboxylic Acids, Esters and Their Derivatives. New York: Wiley, 1991.


Andrew J. Poss

KEY TERMS

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Acetates

—Esters that are based on acetic acid or vinegar as their acid component.

User Comments

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almost 4 years ago

I want to know more about esterification

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almost 4 years ago



I need a continuous process flow sheet of manufacturing butyl acetate by using acetic acid and ethanol (esterification method with packing column).



Can you tell me how to calculate steam required for this entire process. Whats a process temperature? Give me a process details. I need it.

Sincerely

H.Ghafouri





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over 6 years ago

it was helpful. i love to read it. references are great.



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almost 5 years ago

I need a process flow sheet of manufacturing ethyl acetate by using acetic acid and ethanol (esterification method).

Can you tell me how to calculate steam required for this entire process. Whats a process temperature? Give me a process details. I need it.



Sincerely

Veena

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over 3 years ago

I like it that way you presented the answer

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2 months ago

thank you

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almost 2 years ago

I want the exact ratio of alcohol and catalyst to be mixed with the oil.

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almost 2 years ago

I want the exact ratio of alcohol and catalyst to be mixed with the oil

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almost 2 years ago

I want the exact ratio of alcohol and catalyst to be mixed with the oil

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about 2 years ago

please i need your help on the of organic chemistry esp on this esterification. thanks

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about 2 years ago

please help me with the equations of the following ; Isopropyl acetate,
Methyl acetate ,Tert butyl acetate,
Phenyl acetate

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about 2 years ago

please help me with the equations of the following ; Isopropyl acetate,
Methyl acetate ,Tert butyl acetate,
Phenyl acetate

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about 2 years ago

please help me with the equations of the following ; Isopropyl acetate,
Methyl acetate ,Tert butyl acetate,
Phenyl acetate

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over 2 years ago

quelles précaution doit-on prendre en manipulant l'anhydride éthanoïque et l'acide sulfurique concentré?

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almost 3 years ago

ขอบคุณค่ะ(Thank you)

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about 3 years ago

i wantto know the reaction procedure of acetyl tri butyl citrate. other than matel catalyst for DI ALLYL PHTHALATE. Also i want know procedure for Di Allyl Phthalate from allyl acetaye.

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over 3 years ago

I need process flow sheet of manufacturing butyl acetate by using acetic acid and ethanol & sulphuric acid as a catalyst. (esterification method with packing column).





Can you please tell me how to calculate steam required for this entire process. Whats a process temperature & pressure? I need all the process details.

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over 3 years ago

sir, can you suugest any easter which can easilly mix with polyol. we are usung polyol for maqking sole

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over 3 years ago

sir, can you suugest any easter which can easilly mix with polyol. we are usung polyol for maqking sole

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almost 4 years ago

i want esterification chart of squash

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about 4 years ago

Hi,

i need procedure of acetyl-salicyl-salicylicacid, that is the esterification of aspirin carboxylic group with hydroxyl group of salicylic acid.......

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about 4 years ago

i need prosses of esterification from salicylic acid and ethanol

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over 4 years ago

Hi,

I would like to seek the information regarding to the production of butyl acetate. currently there are extensive research in continuous process. Does the batch process is valid now days?

Do you have the statistic of manufacturer of butyl acetate?

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almost 5 years ago

I need a process flow sheet of esterification method for ethanol & 2-carbaxy benzaldihyde

. Whats a process temperature? Give me a process details. I need i

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over 6 years ago

this page is soooooo skeeeet. i love it very much thanks for making it so skeet to use its very helpful.