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https://www.cliffsnotes.com/study-guides/chemistry/organic-chemistry-ii/aldehydes-and-ketones/reactions-of-aldehydes-and-ketones#:~:text=Aldehydes%20and%20ketones%20undergo%20a,mention%20a%20few%20representative%20examples.

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Aldehydes and ketones undergo a variety of reactions that lead to many different products. The most common reactions are nucleophilic addition reactions, which lead to the formation of alcohols, alkenes, diols, cyanohydrins (RCH(OH)C&tbond;N), and imines R ₂ C&dbond;NR), to mention a few representative examples.

Reactions of carbonyl groups

The main reactions of the carbonyl group are nucleophilic additions to the carbon‐oxygen double bond. As shown below, this addition consists of adding a nucleophile and a hydrogen across the carbon‐oxygen double bond.

Due to differences in electronegativities, the carbonyl group is polarized. The carbon atom has a partial positive charge, and the oxygen atom has a partially negative charge.

Aldehydes are usually more reactive toward nucleophilic substitutions than ketones because of both steric and electronic effects. In aldehydes, the relatively small hydrogen atom is attached to one side of the carbonyl group, while a larger R group is affixed to the other side. In ketones, however, R groups are attached to both sides of the carbonyl group. Thus, steric hindrance is less in aldehydes than in ketones.

Electronically, aldehydes have only one R group to supply electrons toward the partially positive carbonyl carbon, while ketones have two electron‐supplying groups attached to the carbonyl carbon. The greater amount of electrons being supplied to the carbonyl carbon, the less the partial positive charge on this atom and the weaker it will become as a nucleus.

Addition of water

The addition of water to an aldehyde results in the formation of a hydrate.

The formation of a hydrate proceeds via a nucleophilic addition mechanism.

1. Water, acting as a nucleophile, is attracted to the partially positive carbon of the carbonyl group, generating an oxonium ion.

2. The oxonium ion liberates a hydrogen ion that is picked up by the oxygen anion in an acid‐base reaction.

Small amounts of acids and bases catalyze this reaction. This occurs because the addition of acid causes a protonation of the oxygen of the carbonyl group, leading to the formation of a full positive charge on the carbonyl carbon, making the carbon a good nucleus. Adding hydroxyl ions changes the nucleophile from water (a weak nucleophile) to a hydroxide ion (a strong nucleophile). Ketones usually do not form stable hydrates.

Addition of alcohol

Reactions of aldehydes with alcohols produce either hemiacetals (a functional group consisting of one -OH group and one -OR group bonded to the same carbon) or acetals (a functional group consisting of two -OR groups bonded to the same carbon), depending upon conditions. Mixing the two reactants together produces the hemiacetal. Mixing the two reactants with hydrochloric acid produces an acetal. For example, the reaction of methanol with ethanal produces the following results:

A nucleophilic substitution of an OH group for the double bond of the carbonyl group forms the hemiacetal through the following mechanism:

1. An unshared electron pair on the alcohol's oxygen atom attacks the carbonyl group.

2. The loss of a hydrogen ion to the oxygen anion stabilizes the oxonium ion formed in Step 1.

The addition of acid to the hemiacetal creates an acetal through the following mechanism:

1. The proton produced by the dissociation of hydrochloric acid protonates the alcohol molecule in an acid‐base reaction.

2. An unshared electron pair from the hydroxyl oxygen of the hemiacetal removes a proton from the protonated alcohol.

3. The oxonium ion is lost from the hemiacetal as a molecule of water.

4. A second molecule of alcohol attacks the carbonyl carbon that is forming the protonated acetal.

5. The oxonium ion loses a proton to an alcohol molecule, liberating the acetal.

Stability of acetals

Acetal formation reactions are reversible under acidic conditions but not under alkaline conditions. This characteristic makes an acetal an ideal protecting group for aldehyde molecules that must undergo further reactions. A protecting group is a group that is introduced into a molecule to prevent the reaction of a sensitive group while a reaction is carried out at some other site in the molecule. The protecting group must have the ability to easily react back to the original group from which it was formed. An example is the protection of an aldehyde group in a molecule so that an ester group can be reduced to an alcohol.

In the previous reaction, the aldehyde group is converted into an acetal group, thus preventing reaction at this site when further reactions are run on the rest of the molecule.

Notice in the previous reaction that the ketone carbonyl group has been reduced to an alcohol by reaction with LiAlH ₄. The protected aldehyde group has not been reduced. Hydrolysis of the reduction product recreates the original aldehyde group in the final product.

Addition of hydrogen cyanide

The addition of hydrogen cyanide to a carbonyl group of an aldehyde or most ketones produces a cyanohydrin. Sterically hindered ketones, however, don't undergo this reaction.

The mechanism for the addition of hydrogen cyanide is a straightforward nucleophilic addition across the carbonyl carbony oxygen bond.

Addition of ylides (the Wittig reaction)

The reaction of aldehydes or ketones with phosphorus ylides produces alkenes of unambiguous double‐bond locations. Phosphorous ylides are prepared by reacting a phosphine with an alkyl halide, followed by treatment with a base. Ylides have positive and negative charges on adjacent atoms.

The following illustration shows the preparation of 2‐methylbutene by a Wittig reaction.

Addition of organometallic reagents

Grignard reagents, organolithium compounds, and sodium alkynides react with formaldehyde to produce primary alcohols, all other aldehydes to produce secondary alcohols, and ketones to produce tertiary alcohols.

Addition of ammonia derivatives

Aldehydes and ketones react with primary amines to form a class of compounds called imines.

The mechanism for imine formation proceeds through the following steps:

1. An unshared pair of electrons on the nitrogen of the amine is attracted to the partial‐positive carbon of the carbonyl group.

2. A proton is transferred from the nitrogen to the oxygen anion.

3. The hydroxy group is protonated to yield an oxonium ion, which easily liberates a water molecule.

4. An unshared pair of electrons on the nitrogen migrate toward the positive oxygen, causing the loss of a water molecule.

5. A proton from the positively charged nitrogen is transferred to water, leading to the imine's formation.

Imines of aldehydes are relatively stable while those of ketones are unstable. Derivatives of imines that form stable compounds with aldehydes and ketones include phenylhydrazine, 2,4‐dinitrophenylhydrazine, hydroxylamine, and semicarbazide.

Oximes, 2,4‐dinitrophenylhydrazones, and semicarbazones are often used in qualitative organic chemistry as derivatives for aldehydes and ketones.

Oxidations of aldehydes and ketones

Aldehydes can be oxidized to carboxylic acid with both mild and strong oxidizing agents. However, ketones can be oxidized to various types of compounds only by using extremely strong oxidizing agents. Typical oxidizing agents for aldehydes include either potassium permanganate (KMnO ₄) or potassium dichromate (K ₂Cr ₂O ₇) in acid solution and Tollens reagent. Peroxy acids, such as peroxybenzoic acid:

Baeyer‐Villiger oxidation is a ketone oxidation, and it requires the extremely strong oxidizing agent peroxybenzoic acid. For example, peroxybenzoic acid oxidizes phenyl methyl ketone to phenyl acetate (an ester).

Aldol reactions

In addition to nucleophilic additions, aldehydes and ketones show an unusual acidity of hydrogen atoms attached to carbons alpha (adjacent) to the carbonyl group. These hydrogens are referred to as α hydrogens, and the carbon to which they are bonded is an α carbon. In ethanal, there is one α carbon and three α hydrogens, while in acetone there are two α carbons and six α hydrogens.

Although weakly acidic (K a 10 −19 to 10 −20), α hydrogens can react with strong bases to form anions. The unusual acidity of α hydrogens can be explained by both the electron withdrawing ability of the carbony group and resonance in the anion that forms. The electron withdrawing ability of a carbonyl group is caused by the group's dipole nature, which results from the differences in electronegativity between carbon and oxygen.

The anion formed by the loss of an α hydrogen can be resonance stabilized because of the mobility of the π electrons that are on the adjacent carbonyl group.

The resonance, which stabilizes the anion, creates two resonance structures - an enol and a keto form. In most cases, the keto form is more stable.

Halogenation of ketones

In the presence of a base, ketones with α hydrogens react to form α haloketones.

Likewise, when methyl ketones react with iodine in the presence of a base, complete halogenation occurs.

The generation of sodium hypoiodate in solution from the reaction of iodine with sodium hydroxide leads to the formation of iodoform and sodium benzoate, as shown here.

Because iodoform is a pale yellow solid, this reaction is often run as a test for methyl ketones and is called the iodoform test.

Aldol condensation

Aldehydes that have α hydrogens react with themselves when mixed with a dilute aqueous acid or base. The resulting compounds, β‐hydroxy aldehydes, are referred to as aldol compounds because they possess both an aldehyde and alcohol functional group.

The aldol condensation proceeds via a carbanion intermediate. The mechanism of base‐catalyzed aldol condensation follows these steps:

1. The base removes an α hydrogen.

2. The carbanion undergoes nucleophilic addition with the carbonyl group of a second molecule of ethanal, which leads to formation of the condensation product.

3. A reaction with water protonates the alkoxide ion.

If the aldol is heated in basic solution, the molecule can be dehydrated to form an α β‐unsaturated aldehyde.

Cross-aldol condensation

An aldol condensation between two different aldehydes produces a cross‐aldol condensation. If both aldehydes possess α hydrogens, a series of products will form. To be useful, a cross‐aldol must be run between an aldehyde possessing an α hydrogen and a second aldehyde that does not have α hydrogens.

Ketonic aldol condensation

Ketones are less reactive towards aldol condensations than alde‐hydes. With acid catalysts, however, small amounts of aldol product can be formed. But the Aldol product that forms will rapidly dehydrate to form a resonance‐stabilized product. This dehydration step drives the reaction to completion.

The acid‐catalyzed aldol condensation includes two key steps: the conversion of the ketone into its enolic form, and the attack on a protonated carbonyl group by the enol. The mechanism proceeds as follows:

1. The oxygen of the carbonyl group is protonated.

2. A water molecule acting as a base removes an acidic α hydrogen, which leads to an enol.

3. The enol attacks a protonated carbonyl group of a second ketone molecule.

Cyclizations via aldol condensation

Internal aldol condensations (condensations where both carbonyl groups are on the same chain) lead to ring formation.

The mechanism for cyclization via an aldol proceeds through an enolate attack on the aldehyde carbonyl.

1. The hydroxy ion removes a hydrogen ion α to the ketone carbonyl.

2. The enolate ion attacks the aldehyde carbonyl, closing the ring.

3. The alkoxide ion abstracts a proton from water in an acid‐base reaction.

4. The base removes a hydrogen ion to form a resonance‐stabilized molecule.

The benzoin condensation

Aromatic aldehydes form a condensation product when heated with a cyanide ion dissolved in an alcohol‐water solution. This condensation leads to the formation of α hydroxy ketones.

The cyanide ion is the only known catalyst for this condensation, because the cyanide ion has unique properties. For example, cyanide ions are relatively strong nucleophiles, as well as good leaving groups. Likewise, when a cyanide ion bonds to the carbonyl group of the aldehyde, the intermediate formed is stabilized by resonance between the molecule and the cyanide ion. The following mechanism illustrates these points.

The benzoin condensation reaction proceeds via a nucleophilic substitution followed by a rearrangement reaction.

1. The cyanide ion is attracted to the carbon atom of the carbonyl group.

2. The carbanion is resonance‐stabilized.

3. The carbanion attacks a second molecule of benzaldehyde.

4. The alkoxide ion removes a proton from the hydroxide group.

5. A pair of electrons on the alkoxide ion are attracted to the carbon bonded to the cyanide group, which then leaves to generate the product.

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Aldehydes and ketones undergo a variety of reactions that lead to many different products. The most common reactions are nucleophilic addition reactions, which lead to the formation of alcohols, alkenes, diols, cyanohydrins (RCH(OH)C&tbond;N), and imines R 2 C&dbond;NR), to mention a few representative examples.

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https://en.wikipedia.org/wiki/Ketone#:~:text=In%20chemistry%2C%20a%20ketone%20%2F%CB%88,C(O)CH3.

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In chemistry, a ketone is a functional group with the structure R ₂C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl), with the formula CH ₃C(O)CH ₃. Many ketones are of great importance in biology and in industry. Examples include many sugars ( ketoses), many steroids (e.g., testosterone), and the solvent acetone.

According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix -ane of the parent alkane to -anone. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names, although some introductory chemistry textbooks use systematic names such as "2-propanone" or "propan-2-one" for the simplest ketone ( C H ₃−C O−CH ₃) instead of "acetone".

The derived names of ketones are obtained by writing separately the names of the two alkyl groups attached to the carbonyl group, followed by "ketone" as a separate word. The names of the alkyl groups are written in order of increasing complexity: for example, methyl ethyl ketone. According to the rules of IUPAC nomenclature, the alkyl groups are written alphabetically, i.e., ethyl methyl ketone. When the two alkyl groups are the same, the prefix "di-" is added before the name of alkyl group. The positions of other groups are indicated by Greek letters, the α-carbon being the atom adjacent to carbonyl group.

Although used infrequently, oxo is the IUPAC nomenclature for the oxo group (=O) and used as prefix when the ketone does not have the highest priority. Other prefixes, however, are also used. For some common chemicals (mainly in biochemistry), keto refer to the ketone functional group.

The ketone carbon is often described as "sp ² hybridized", a description that includes both their electronic and molecular structure. Ketones are trigonal planar around the ketonic carbon, with C−C−O and C−C−C bond angles of approximately 120°. Ketones differ from aldehydes in that the carbonyl group (CO) is bonded to two carbons within a carbon skeleton. In aldehydes, the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. Ketones are also distinct from other carbonyl-containing functional groups, such as carboxylic acids, esters and amides.

The carbonyl group is polar because the electronegativity of the oxygen is greater than that for carbon. Thus, ketones are nucleophilic at oxygen and electrophilic at carbon. Because the carbonyl group interacts with water by hydrogen bonding, ketones are typically more soluble in water than the related methylene compounds. Ketones are hydrogen-bond acceptors. Ketones are not usually hydrogen-bond donors and cannot hydrogen-bond to themselves. Because of their inability to serve both as hydrogen-bond donors and acceptors, ketones tend not to "self-associate" and are more volatile than alcohols and carboxylic acids of comparable molecular weights. These factors relate to the pervasiveness of ketones in perfumery and as solvents.

Ketones are classified on the basis of their substituents. One broad classification subdivides ketones into symmetrical and unsymmetrical derivatives, depending on the equivalency of the two organic substituents attached to the carbonyl center. Acetone and benzophenone (C ₆H ₅C(O)C ₆H ₅) are symmetrical ketones. Acetophenone (C ₆H ₅C(O)CH ₃) is an unsymmetrical ketone.

Many kinds of diketones are known, some with unusual properties. The simplest is diacetyl (CH ₃C(O)C(O)CH ₃), once used as butter-flavoring in popcorn. Acetylacetone (pentane-2,4-dione) is virtually a misnomer (inappropriate name) because this species exists mainly as the monoenol CH ₃C(O)CH=C(OH)CH ₃. Its enolate is a common ligand in coordination chemistry.

Unsaturated ketones

Ketones containing alkene and alkyne units are often called unsaturated ketones. The most widely used member of this class of compounds is methyl vinyl ketone, CH ₃C(O)CH=CH ₂, which is useful in the Robinson annulation reaction. Lest there be confusion, a ketone itself is a site of unsaturation; that is, it can be hydrogenated.

Cyclic ketones

Many ketones are cyclic. The simplest class have the formula (CH ₂)nCO, where n varies from 2 for cyclopropanone to the tens. Larger derivatives exist. Cyclohexanone, a symmetrical cyclic ketone, is an important intermediate in the production of nylon. Isophorone, derived from acetone, is an unsaturated, asymmetrical ketone that is the precursor to other polymers. Muscone, 3-methylpentadecanone, is an animal pheromone. Another cyclic ketone is cyclobutanone, having the formula C ₄H ₆ O.

Ketones that have at least one alpha-hydrogen, undergo keto-enol tautomerization; the tautomer is an enol. Tautomerization is catalyzed by both acids and bases. Usually, the keto form is more stable than the enol. This equilibrium allows ketones to be prepared via the hydration of alkynes.

Acid/base properties of ketones

C-H bonds adjacent to the carbonyl in ketones are more acidic ( ≈ 20) than the C-H bonds in alkane (p K a ≈ 50). This difference reflects resonance stabilization of the enolate ion that is formed upon deprotonation. The relative acidity of the α-hydrogen is important in the enolization reactions of ketones and other carbonyl compounds. The acidity of the α-hydrogen also allows ketones and other carbonyl compounds to react as nucleophiles at that position, with either stoichiometric and catalytic base. Using very strong bases like lithium diisopropylamide (LDA, p K a of conjugate acid ~36) under non-equilibrating conditions (-78 °C, 1.1 equiv LDA in THF, ketone added to base), the less-substituted kinetic enolate is generated selectively, while conditions that allow for equilibration (higher temperature, base added to ketone, using weak or insoluble bases, e.g., NaOEt in EtOH, or NaH) provides the more-substituted thermodynamic enolate.

Ketones are also weak bases, undergoing protonation on the carbonyl oxygen in the presence of Brønsted acids. Ketonium ions (i.e., protonated ketones) are strong acids, with p K a values estimated to be somewhere between -5 and -7. Although acids encountered in organic chemistry are seldom strong enough to fully protonate ketones, the formation of equilibrium concentrations of protonated ketones is nevertheless an important step in the mechanisms of many common organic reactions, like the formation of an acetal, for example. Acids as weak as pyridinium cation (as found in pyridinium tosylate) with a p K a of 5.2 are able to serve as catalysts in this context, despite the highly unfavorable equilibrium constant for protonation ( K eq < 10 −10).

An aldehyde differs from a ketone in that it has a hydrogen atom attached to its carbonyl group, making aldehydes easier to oxidize. Ketones do not have a hydrogen atom bonded to the carbonyl group, and are therefore more resistant to oxidation. They are oxidized only by powerful oxidizing agents which have the ability to cleave carbon-carbon bonds.

Ketones and aldehydes absorb strongly in the infra-red spectrum near 1700 . The exact position of the peak depends on the substituents.

Whereas spectroscopy is generally not useful for establishing the presence of a ketone, spectra exhibit signals somewhat downfield of 200 ppm depending on structure. Such signals are typically weak due to the absence of nuclear Overhauser effects. Since aldehydes resonate at similar chemical shifts, multiple resonance experiments are employed to definitively distinguish aldehydes and ketones.

Ketones give positive results in Brady's test, the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with Tollens' reagent or with Fehling's solution. Methyl ketones give positive results for the iodoform test. Ketones also give positive results when treated with m-dinitrobenzene in presence of dilute sodium hydroxide to give violet coloration.

Many methods exist for the preparation of ketones in industrial scale and academic laboratories. Ketones are also produced in various ways by organisms; see the section on biochemistry below.

In industry, the most important method probably involves oxidation of hydrocarbons, often with air. For example, a billion kilograms of cyclohexanone are produced annually by aerobic oxidation of cyclohexane. Acetone is prepared by air-oxidation of cumene.

For specialized or small scale organic synthetic applications, ketones are often prepared by oxidation of secondary alcohols:

Typical strong oxidants (source of "O" in the above reaction) include potassium permanganate or a Cr(VI) compound. Milder conditions make use of the Dess-Martin periodinane or the Moffatt-Swern methods.

Many other methods have been developed, examples include:

By hydration of alkynes. Such processes occur via enols and require the presence of an acid and . Subsequent enol-keto tautomerization gives a ketone. This reaction always produces a ketone, even with a terminal alkyne, the only exception being the hydration of acetylene, which produces acetaldehyde.

From Weinreb Amides using stoichiometric organometallic reagents.

Aromatic ketones can be prepared in the Friedel-Crafts acylation, the related Houben-Hoesch reaction, and the Fries rearrangement.

Ozonolysis, and related dihydroxylation/oxidative sequences, cleave alkenes to give aldehydes or ketones, depending on alkene substitution pattern.

In the Kornblum-DeLaMare rearrangement ketones are prepared from peroxides and base.

In the Ruzicka cyclization, cyclic ketones are prepared from dicarboxylic acids.

In the Nef reaction, ketones form by hydrolysis of salts of secondary nitro compounds.

In the Fukuyama coupling, ketones form from a thioester and an organozinc compound.

The Dakin-West reaction provides an efficient method for preparation of certain methyl ketones from carboxylic acids.

Ketones can also be prepared by the reaction of Grignard reagents with nitriles, followed by hydrolysis.

By decarboxylation of carboxylic anhydride.

Ketones can be prepared from haloketones in reductive dehalogenation of halo ketones.

In ketonic decarboxylation symmetrical ketones are prepared from carboxylic acids.

Oxidation of amines with iron(III) chloride.

Acid-catalysed rearrangement of 1,2-diols.

Ketones engage in many organic reactions. The most important reactions follow from the susceptibility of the carbonyl carbon toward nucleophilic addition and the tendency for the enolates to add to electrophiles. Nucleophilic additions include in approximate order of their generality:

Ketones are pervasive in nature. The formation of organic compounds in photosynthesis occurs via the ketone ribulose-1,5-bisphosphate. Many sugars are ketones, known collectively as ketoses. The best known ketose is fructose; it exists as a cyclic hemiketal, which masks the ketone functional group. Fatty acid synthesis proceeds via ketones. Acetoacetate is an intermediate in the Krebs cycle which releases energy from sugars and carbohydrates.

In medicine, acetone, acetoacetate, and beta-hydroxybutyrate are collectively called ketone bodies, generated from carbohydrates, fatty acids, and amino acids in most vertebrates, including humans. Ketone bodies are elevated in the blood ( ketosis) after fasting, including a night of sleep; in both blood and urine in starvation; in hypoglycemia, due to causes other than hyperinsulinism; in various inborn errors of metabolism, and intentionally induced via a ketogenic diet, and in ketoacidosis (usually due to diabetes mellitus). Although ketoacidosis is characteristic of decompensated or untreated type 1 diabetes, ketosis or even ketoacidosis can occur in type 2 diabetes in some circumstances as well.

Ketones are produced on massive scales in industry as solvents, polymer precursors, and pharmaceuticals. In terms of scale, the most important ketones are acetone, methylethyl ketone, and cyclohexanone. They are also common in biochemistry, but less so than in organic chemistry in general. The combustion of hydrocarbons is an uncontrolled oxidation process that gives ketones as well as many other types of compounds.

Although it is difficult to generalize on the toxicity of such a broad class of compounds, simple ketones are, in general, not highly toxic. This characteristic is one reason for their popularity as solvents. Exceptions to this rule are the unsaturated ketones such as methyl vinyl ketone with of 7 mg/kg (oral).

Media related to Ketones at Wikimedia Commons

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In chemistry, a ketone is a functional group with the structure R 2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl), with the formula CH 3C(O)CH 3.

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https://www.britannica.com/science/resin

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resin, any natural or synthetic organic compound consisting of a noncrystalline or viscous liquid substance. Natural resins are typically fusible and flammable organic substances that are transparent or translucent and are yellowish to brown in colour. They are formed in plant secretions and are soluble in various organic liquids but not in water. Synthetic resins comprise a large class of synthetic products that have some of the physical properties of natural resins but are different chemically. Synthetic resins are not clearly differentiated from plastics.

Most natural resins are exuded from trees, especially pines and firs. Resin formation occurs as a result of injury to the bark from wind, fire, lightning, or other cause. The fluid secretion ordinarily loses some of its more volatile components by evaporation, leaving a soft residue at first readily soluble but becoming insoluble as it ages. The ancient Chinese, Japanese, Egyptians, and others used resins in preparation of lacquers and varnishes.

Natural resins may be classified as spirit-soluble and oil-soluble. Among the former are balsams, long popular as a healing agent; turpentines used as solvents; and mastics, dragon's blood, dammar, sandarac, and the lacs, all used as components of varnishes. The oil-soluble resins include rosin, derived along with turpentine from the long-leaf pine and long used for a variety of applications, including soapmaking; copals, used in varnishes; amber, the hardest natural resin, fabricated into jewelry; Oriental lacquer, derived from a tree native to China; and cashew-nutshell oil, derived from cashew nuts.

In modern industry natural resins have been almost entirely replaced by synthetic resins, which are divided into two classes, thermoplastic resins, which remain plastic after heat treatment, and thermosetting resins, which become insoluble and infusible on heating.

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Resin | Synthetic, Polymerization, Thermosetting

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Resin, any natural or synthetic organic compound consisting of a noncrystalline or viscous liquid substance. Natural resins are typically fusible and flammable organic substances that are transparent or translucent and are yellowish to brown in colour. They are formed in plant secretions and are

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USES
They are most widely used as solvents, especially in industries manufacturing explosives, lacquers, paints, and textiles. Ketones are also used in tanning, as preservatives, and in hydraulic fluids. The most important ketone is acetone (CH ₃ COCH ₃), a liquid with a sweetish odour.

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REACTIONS

ketones undergo a variety of reactions that lead to many different products. The most common reactions are nucelophilic adition reactions, which lead to the formation of alcohols, alkenes, diols, cyanohydrins (RCH(OH)C&tbond;N), and imines R 2C&dbond;NR), to mention a few representative examples

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STRUCTURES
In chemistry, a ketone /ˈkiːtoʊn/ is a functional group with the structure R ₂ C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl), with the formula CH ₃ C(O)CH ₃.

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STRUCTURES

testosterone
muscone
vainilil
citral
cortisone

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KETONES

ketone, any of a class of organic compounds characterized by the presence of a carbonyl group in which the carbon atom is covalently bonded to an oxygen atom. The remaining two bonds are to other carbon atoms or hydrocarbon radicals (R): Ketone compounds have important physiological properties