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Carbonyl Compounds: Nomenclature, Nucleophilic Addition, and More

Many of the materials we use in our daily lives contain carbonyl compounds–from pharmaceutical agents to cosmetic products. This article will discuss carbonyl compounds, focusing on their structures and chemical reactions. A particularly important group of carbonyl compounds, known as carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates, will also be discussed in this article.

Last updated: 7 Mar, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Carbonyl Compounds

In organic chemistry, carbonyl compounds are a functional group consisting of a carbon atom with a double bond to an oxygen atom. Many different kinds of carbonyl compounds are present in nature. They all contain an acyl group (R-C=O) with another substituent attached to it. The R part of the structure can be any alkyl, alkenyl, or alkynyl, or have other functional groups attached to it.

Bonded to the other side of the acyl group is either hydrogen, carbon, oxygen, nitrogen Nitrogen An element with the atomic symbol n, atomic number 7, and atomic weight [14. 00643; 14. 00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth’s atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells. Urea Cycle, sulfur, or a halogen. Depending on the different substituents attached to the acyl group, different types of compounds can be formed.

Different types of carbonyl compounds with their general chemical structures

Different types of carbonyl compounds with their general chemical structures

Image by Mark Xavier Bailon.

Carbonyl compounds are generally divided into 2 groups. One category is composed of the aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates, the other composed of the carboxylic acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance and their derivatives. These two groups generally differ in their kinds of chemistry and reactions.

Aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates are functions in the second degree of oxidation. They are considered derivatives of a hydrocarbon with substitution of 2 hydrogen atoms in the same carbon for one of oxygen, giving rise to an oxo group (=O). If the substitution takes place on a primary carbon, the resulting compound is an aldehyde and is named with the ending -al. If the substitution takes place on a secondary carbon, it is a ketone and is named with the suffix -one.

Aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates, having an H or a C bonded to the acyl group, can’t participate in nucleophilic substitution reactions because these two atoms cannot stabilize a negative charge. These substituents cannot participate as a leaving group in nucleophilic substitution reactions due to their inability to stabilize negative charges.

For carboxylic acid and its derivatives, the atom directly attached to the acyl group (oxygen, nitrogen Nitrogen An element with the atomic symbol n, atomic number 7, and atomic weight [14. 00643; 14. 00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth’s atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells. Urea Cycle, sulfur, halogen) can stabilize negative charges and, therefore, can participate in nucleophilic substitution reactions.

Carbonyl Structure

The carbonyl group is a functional group composed of carbon and oxygen atoms connected by a double bond. The hybridization Hybridization The genetic process of crossbreeding between genetically dissimilar parents to produce a hybrid. Blotting Techniques of the carbon atom is sp2 and therefore forms three σ bonds and one π bond. The oxygen atom, on the other hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy, forms one σ and π bond with the carbonyl carbon and has 2 non-bonding pairs of electrons.

The difference between the electronegativity values of carbon and oxygen produces a strongly polarized double bond. The oxygen atom is more electronegative and, therefore, has a higher tendency to attract electrons, creating a partially negative end. In turn, the carbon atom becomes partially positive from the pull of electrons toward the oxygen atom.

Nomenclature of Aldehydes and Ketones

In naming aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and  ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates, the terminal –e of the corresponding alkane is replaced by – al AL Amyloidosis or –one, respectively. For aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates, the parent chain should contain the –CHO group. If the aldehyde functional group is the functional group of highest priority, the carbonyl carbon is assigned as carbon 1. For example, in the case of propane, when two of the hydrogen atoms on the terminal carbon are replaced by an oxygen atom double bonded to the carbon atom, the name of the aldehyde described is propanal.

A cyclic aldehyde is a compound where an aldehyde group is directly attached to a ring. In naming these types of compounds, the suffix –carbaldehyde is added to the name of the cyclic compound. For example, a cyclopentane with an aldehyde group attached to it will be named cyclopentanecarbaldehyde. The figure below shows different aldehyde compounds with their names.

Structures and names of some aldehydes

Structures and names of some aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates

Image by Mark Xavier Bailon.

Ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates are named by replacing the terminal –e of the parent hydrocarbon with –one. For compounds containing ketone as the functional group of highest priority, the parent chain is the longest chain containing the ketone functional group. The assignment of a carbon number proceeds in the direction giving the carbonyl carbon the lowest possible number. In the new International Union of Pure and Applied Chemistry (IUPAC) system of naming, the locant number is placed before the suffix.

The parent compound is pentane as it is a 5-carbon alkane. The lowest possible number for the carbonyl carbon is 2 when counting is started from the rightmost carbon atom. In this case, the name of the compound will be pent-2-one.

Chemical structure of pent-2-one

Nucleophilic Addition

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 Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates 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 Attachment The binding of virus particles to virus receptors on the host cell surface, facilitating virus entry into the cell. Virology, 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 Product A molecule created by the enzymatic reaction. Basics of Enzymes. Below is the mechanism of the nucleophilic addition reaction.

Mechanism of nucleophilic addition reaction of aldehyde

Mechanism of nucleophilic addition reaction of aldehyde

Image by Mark Xavier Bailon.

Carbohydrates

Carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of 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. In photosynthesis, plants Plants Cell Types: Eukaryotic versus Prokaryotic facilitate the reaction between carbon dioxide and water, in the presence of solar energy, through enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes present in the plant’s cells, producing carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates and oxygen molecules.

Carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates are a broad class of polyhydroxylated aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates and are generally called sugars. The term carbohydrate was derived from glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance having the molecular formula of C6H12O6 and was originally thought to be a hydrate of carbon.

The presence of the hydroxyl group in glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance enables it to form a ring instead of being an open-chain aldehyde. In the case of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance, 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 Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance 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 Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment their reactivity and ability to be metabolized by the body.

Carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates provide more than 50% of the energy needed for metabolism, growth, repair, secretion Secretion Coagulation Studies, absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption, excretion, and mechanical work. Metabolism of carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates includes reactions experienced by carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates from food sources or those formed from compounds of other carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates. The oxidation of this type of carbohydrate allows energy storage in the form of glycogen, synthesis Synthesis Polymerase Chain Reaction (PCR) of non-essential amino acids Non-essential amino acids Basics of Amino Acids, and production of fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance in the presence of an excess of carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates.

Oxidation and Reduction

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 Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates are more reactive than ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates because they are less hindered due to the presence of only an H atom instead of an alkyl group as their substituent. Therefore, aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates can also participate in other types of reactions depending on the reaction conditions.

In the presence of strong oxidants like potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia permanganate and potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia dichromate, aldehyde can be oxidized to produce carboxylic acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance. For example, when propanal is oxidized by potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia dichromate, propanoic acid is produced.

Oxidation of propanal

Oxidation of propanal

Image by Mark Xavier Bailon.

On the other hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy, both aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates can undergo reduction reactions. Both can react with reducing agents, such as sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia borohydride or hydrogen gas, in the presence of a Lindlar’s catalyst to produce alcohol. Aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates produce primary alcohols through reduction, while ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates produce secondary alcohols.

Reduction reactions of aldehydes and ketones

Reduction reactions of aldehydes Aldehydes Organic compounds containing a carbonyl group in the form -cho. Basics of Carbohydrates and ketones Ketones Organic compounds containing a carbonyl group =C=O bonded to two hydrocarbon groups. Basics of Carbohydrates

Image by Mark Xavier Bailon.

References

  1. McMurry, J. (2008). Organic Chemistry. 7th ed. USA. Brooks/Cole, Thomson Learning Inc.
  2. Carey, F. (2000). Organic Chemistry. 4th ed. USA. McGraw-Hill Companies, Inc.

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