In this case, the name of the compound will be pentone. A nucleophile is any chemical species that has a high electron density and is attracted to an electrophilic atom in another molecule, such as the low electron density of the carbonyl carbon.
The carbonyl group provides a site for nucleophilic addition also known as nucleophilic attack and increases the acidity of the hydrogen atoms attached to alpha carbon. These two effects are consistent with the structure of the carbonyl groups and are due to the ability of oxygen to incorporate a negative charge.
Reactions of aldehydes and ketones are limited to nucleophilic addition reactions only. The attack of the nucleophile is through the electrophilic carbon atom of the target molecule. The electrophilic carbon atom becomes somewhat electron-deficient due to the pull of electrons toward the oxygen atoms. Because of this, the carbonyl carbon becomes highly susceptible to a nucleophilic attack. Only addition of the nucleophile occurs since the H and C atom in the substituent is not a good leaving group.
In the process of attachment, the double bond between carbon and oxygen is removed, and a localized negative charge transfers to the oxygen atom forming an alkoxide intermediate.
Protonation of the intermediate results in the formation of a neutral alcohol addition product. Below is the mechanism of the nucleophilic addition reaction:. Carbohydrates are an important carbonyl compound found in nature. They are composed of a long carbon chain as well as a carbonyl group or groups and are mainly synthesized by a process called photosynthesis.
Carbohydrates are a broad class of polyhydroxylated aldehydes and ketones and are generally called sugars. The term carbohydrate was derived from glucose having the molecular formula of C 6 H 12 O 6 and was originally thought to be a hydrate of carbon. The presence of the hydroxyl group in glucose enables it to form a ring instead of being an open-chain aldehyde. In the case of glucose, the hydroxyl group attached to carbon 5 attacks the carbonyl carbon through the nucleophilic addition mechanism.
Since the attack can occur from the top or from the bottom, the cyclic form of glucose can either be in alpha or beta form. When the —OH group in the anomeric carbon original carbonyl carbon is down, the molecule is in alpha form, and when the —OH group is up, it is in its beta form. The specific forms also known as conformations of these sugar molecules are important as they affect their reactivity and ability to be metabolized by the body.
Metabolism of carbohydrates includes reactions experienced by carbohydrates from food sources or those formed from compounds of other carbohydrates. The oxidation of this type of carbohydrate allows energy storage in the form of glycogen, synthesis of non-essential amino acids, and production of fatty acids in the presence of an excess of carbohydrates. Oxidation and reduction reactions occur simultaneously when electrons are transferred. When a molecule is oxidized, it gives up an electron to a neighboring molecule which becomes reduced upon gaining the electron.
In general, aldehydes are more reactive than ketones because they are less hindered due to the presence of only an H atom instead of an alkyl group as their substituent. Therefore, aldehydes can also participate in other types of reactions depending on the reaction conditions. In the presence of strong oxidants like potassium permanganate and potassium dichromate, aldehyde can be oxidized to produce carboxylic acids.
For example, when propanal is oxidized by potassium dichromate, propanoic acid is produced. Keywords: Carboxypeptidase , Esterases , Serine proteases , Thermolysin. Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service.
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