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Is Ketone Neutral?

Addition Of Alcohols To Form Hemiacetals And Acetals

Addition Of Alcohols To Form Hemiacetals And Acetals

In this organic chemistry topic, we shall see how alcohols (R-OH) add to carbonyl groups. Carbonyl groups are characterized by a carbon-oxygen double bond. The two main functional groups that consist of this carbon-oxygen double bond are Aldehydes and Ketones. Introduction It has been demonstrated that water adds rapidly to the carbonyl function of aldehydes and ketones to form geminal-diol. In a similar reaction alcohols add reversibly to aldehydes and ketones to form hemiacetals (hemi, Greek, half). This reaction can continue by adding another alcohol to form an acetal. Hemiacetals and acetals are important functional groups because they appear in sugars. To achieve effective hemiacetal or acetal formation, two additional features must be implemented. First, an acid catalyst must be used because alcohol is a weak nucleophile; and second, the water produced with the acetal must be removed from the reaction by a process such as a molecular sieves or a Dean-Stark trap. The latter is important, since acetal formation is reversible. Indeed, once pure hemiacetal or acetals are obtained they may be hydrolyzed back to their starting components by treatment with aqueous acid and an excess of water. Acetals are geminal-diether derivatives of aldehydes or ketones, formed by reaction with two equivalents (or an excess amount) of an alcohol and elimination of water. Ketone derivatives of this kind were once called ketals, but modern usage has dropped that term. It is important to note that a hemiacetal is formed as an intermediate during the formation of an acetal. Mechanism for Hemiacetal and Acetal Formation The mechanism shown here applies to both acetal and hemiacetal formation 1) Protonation of the carbonyl 2) Nucleophilic attack by the alcohol 3) Deprotonation to form a hemi Continue reading >>

A Monocarboxylate Transporter Required For Hepatocyte Secretion Of Ketone Bodies During Fasting

A Monocarboxylate Transporter Required For Hepatocyte Secretion Of Ketone Bodies During Fasting

Abstract To find new genes that influence liver lipid mass, we performed a genetic screen for zebrafish mutants with hepatic steatosis, a pathological accumulation of fat. The red moon (rmn) mutant develops hepatic steatosis as maternally deposited yolk is depleted. Conversely, hepatic steatosis is suppressed in rmn mutants by adequate nutrition. Adult rmn mutants show increased liver neutral lipids and induction of hepatic lipid biosynthetic genes when fasted. Positional cloning of the rmn locus reveals a loss-of-function mutation in slc16a6a (solute carrier family 16a, member 6a), a gene that we show encodes a transporter of the major ketone body β-hydroxybutyrate. Restoring wild-type zebrafish slc16a6a expression or introducing human SLC16A6 in rmn mutant livers rescues the mutant phenotype. Radiotracer analysis confirms that loss of Slc16a6a function causes diversion of liver-trapped ketogenic precursors into triacylglycerol. Underscoring the importance of Slc16a6a to normal fasting physiology, previously fed rmn mutants are more sensitive to death by starvation than are wild-type larvae. Our unbiased, forward genetic approach has found a heretofore unrecognized critical step in fasting energy metabolism: hepatic ketone body transport. Since β-hydroxybutyrate is both a major fuel and a signaling molecule in fasting, the discovery of this transporter provides a new direction for modulating circulating levels of ketone bodies in metabolic diseases. Continue reading >>

Why Are Aldehydes And Ketones Neutral And Not Acidic/basic?

Why Are Aldehydes And Ketones Neutral And Not Acidic/basic?

This question is quite general, and as other answers have pointed out, depends on what you mean by acidic/basic. The other answers have already covered the Lewis bit, so I will focus a bit more on the Bronsted-Lowry and Arrhenius definitions. In water, almost all aldehydes and ketones do not dissociate to give the H+ or OH- ion, which is the Arrhenius definition. However, the alpha position of acetylacetone is considered acidic by the Bronsted-Lowry definition, and can be deprotonated by strong bases to give the conjugated enone after tautomerism. This is due to the stability of the conjugate base. Continue reading >>

1. Nomenclature Of Aldehydes And Ketones

1. Nomenclature Of Aldehydes And Ketones

Aldehydes and ketones are organic compounds which incorporate a carbonyl functional group, C=O. The carbon atom of this group has two remaining bonds that may be occupied by hydrogen or alkyl or aryl substituents. If at least one of these substituents is hydrogen, the compound is an aldehyde. If neither is hydrogen, the compound is a ketone. The IUPAC system of nomenclature assigns a characteristic suffix to these classes, al to aldehydes and one to ketones. For example, H2C=O is methanal, more commonly called formaldehyde. Since an aldehyde carbonyl group must always lie at the end of a carbon chain, it is by default position #1, and therefore defines the numbering direction. A ketone carbonyl function may be located anywhere within a chain or ring, and its position is given by a locator number. Chain numbering normally starts from the end nearest the carbonyl group. In cyclic ketones the carbonyl group is assigned position #1, and this number is not cited in the name, unless more than one carbonyl group is present. If you are uncertain about the IUPAC rules for nomenclature you should review them now. Examples of IUPAC names are provided (in blue) in the following diagram. Common names are in red, and derived names in black. In common names carbon atoms near the carbonyl group are often designated by Greek letters. The atom adjacent to the function is alpha, the next removed is beta and so on. Since ketones have two sets of neighboring atoms, one set is labeled α, β etc., and the other α', β' etc. Very simple ketones, such as propanone and phenylethanone (first two examples in the right column), do not require a locator number, since there is only one possible site for a ketone carbonyl function. Likewise, locator numbers are omitted for the simple dialdehyde at t Continue reading >>

Chapter 16: Aldehydes And Ketones (carbonyl Compounds)

Chapter 16: Aldehydes And Ketones (carbonyl Compounds)

The Carbonyl Double Bond Both the carbon and oxygen atoms are hybridized sp2, so the system is planar. The three oxygen sp2 AO’s are involved as follows: The two unshared electorn pairs of oxygen occupy two of these AO’s, and the third is involved in sigma bond formation to the carbonyl carbon. The three sp2 AO’s on the carbonyl carbon are involved as follows: One of them is involved in sigma bonding to one of the oxygen sp2 AO’s, and the other two are involved in bonding to the R substituents. The 2pz AO’s on oxygen and the carbonyl carbon are involved in pi overlap, forming a pi bond. The pi BMO, formed by positive overlap of the 2p orbitals, has a larger concentration of electron density on oxygen than carbon, because the electrons in this orbital are drawn to the more electronegative atom, where they are more highly stabilized. This result is reversed in the vacant antibonding MO. As a consequence of the distribution in the BMO, the pi bond (as is the case also with the sigma bond) is highly polar, with the negative end of the dipole on oxygen and the positive end on carbon. We will see that this polarity, which is absent in a carbon-carbon pi bond, has the effect of strongly stabilizing the C=O moiety. Resonance Treatment of the Carbonyl Pi Bond 1.Note that the ionic structure (the one on the right side) has one less covalent bond, but this latter is replaced with an ionic bond (electrostatic bond). 2.This structure is a relatively “good” one, therefore, and contributes extensively to the resonance hybrid, making this bond much more thermodynamically stable than the C=C pi bond, for which the corresponding ionic structure is much less favorable (negative charge is less stable on carbon than on oxygen). 3.The carbonyl carbon therefore has extensive car Continue reading >>

Reactions Of Secondary Amine Derivatives

Reactions Of Secondary Amine Derivatives

Step 1: An acid/base reaction. Protonation of the carbonyl activates it and makes it more susceptible to attack by a neutral nucleophilic like the N of a secondary amine Step 2: Attack of the N nucleophile at the electrophilic C of the C=O group with the electrons from the π bond going to the +ve O. Step 3: An acid/base reaction. Removal of the proton neutralises the +ve charge on the N and forms the carbinolamine intermediate. Step 4: To form the enamine we need to dehydrate. However, before -OH leaves it needs to be protonated, so a simple acid/base reaction. Step 5: Removal of a proton from an adjacent C allows the C=C π bond to form and loss of the leaving group, a neutral water molecule, creating the enamine. Step 1: An acid/base reaction. Since there is only a weak nucleophile we need to activate the carbonyl by protonating on O. Step 2: The nucleophilic O in the water attacks the electrophilic C in the C=O, breaking the π bond and giving the electrons to the positive O Step 3: An acid/base reaction. Deprotonation of the oxonium ion neutralises the charge giving the hydrate. Reactions of Alcohols to give Acetals Reaction type: Nucleophilic Addition then nucleophilic substitution Summary Typical reagents : excess ROH, catalytic p-toluenesulfonic acid (often written as TsOH) in refluxing benzene. Aldehydes and ketones react with two moles of an alcohol to give 1,1-geminal diethers more commonly known as acetals. The term "acetal" used to be restricted to systems derived from aldehydes and the term "ketal" applied to those from ketones, but chemists now use acetal to describe both. Acetals are biologically important due to their role in the chemistry of carbohydrates. Acetals are important chemically due to their role as "protecting groups" The equilibrium is shif Continue reading >>

Is A Ketone An Acid Or A Base?

Is A Ketone An Acid Or A Base?

Ketones are in fact weak acids. This comes from an ability to shift the places of the double bond and one of the hydrogen atoms, resulting in an alcohol compound with a double bond between two of the carbon atoms. This is called an enol, and is less stable than the ketone - the two are in rapid equilibrium. This enol may lose a hydrogen ion to become an enolate. This happens only when a ketone is reacted with a strong base. Continue reading >>

Ketone Synthesis Under Neutral Conditions. Cu(i) Diphenylphosphinate-mediated, Palladium-catalyzed Coupling Of Thiol Esters And Organostannanes

Ketone Synthesis Under Neutral Conditions. Cu(i) Diphenylphosphinate-mediated, Palladium-catalyzed Coupling Of Thiol Esters And Organostannanes

Abstract A versatile approach to ketone synthesis is described. The reaction relies on the palladium-catalyzed, copper diphenylphosphinate-mediated coupling of thiol esters with organostannanes under neutral reaction conditions. This reaction complements the previously described coupling of thiol esters with boronic acids that used dual thiophilic−borophilic activation methodology. Citation data is made available by participants in Crossref's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search inSciFinder. Continue reading >>

General Chemistry

General Chemistry

(3) Amide formation, as illustrated by the reaction below, is the reaction of a carboxylic acid with an amine to yield a new class called an amide. c. Uses of Carboxylic Acids. Many acids, such as acetic, salicylic, and lactic, are used topically to treat local conditions. Others are used systemically. Still others, like citric acid, which is found naturally in lemons, are used to flavor syrups for Aldehydes result from the first oxidation of alcohols and have the general themselves, they have lower boiling points than corresponding alcohols or acids. Again, as with the other classes or organic compounds in table 3-3, the lower- molecular-weight aldehydes (up to five carbons) are soluble in water. Aldehydes are neutral in pH and undergo both oxidation and reduction reactions. They are easily oxidized to acids and reduced to alcohols. Some aldehydes, such as vanillin and benzaldehyde, are frequently used in the pharmacy as flavoring agents. Ketones result from the oxidation of a secondary alcohol and have the general a. Ketones are similar to aldehydes in their boiling points, which are lower than b. Ketones are neutral compounds, being neither acids nor bases. They undergo the process of reduction, by which they are converted to secondary alcohols. c. The ketone functional group appears in the structure of many complex of acetone, are seldom used. Acetone is used as a solvent and cleaning fluid. Esters, as previously mentioned, are formed from the reaction of a carboxylic a. Properties of Esters. The simplest esters are liquids and have fragrant odors. An example is ethyl acetate, CH3-CH2-OOC-CH3, which has the odor of they have boiling points similar to alkanes of similar molecular weight. They can form b. Reactions of Esters. Esters are neutral in pH and undergo two i Continue reading >>

Ketones On Acid

Ketones On Acid

Acids are like an aphrodisiac for carbonyl compounds: it makes them more likely to react with nucleophiles. Let me explain. I said the last two days that carbonyl carbons are important electrophiles: they bear a partial positive charge. Now, I’m going to show how you can make them even more electrophilic – more reactive. This means that reactions that normally wouldn’t happen, will now happen. First, a question: How do we make electrophiles more electrophilic? Simple: we take electrons away from them! How can we take electrons away? With carbonyls, the answer might be a bit counterintuitive. We’re going to add acid to the oxygen, and this will make the carbon more electron-poor. Sounds weird, but it actually makes sense when you think about it. Think about the resonance forms of the carbonyl: its most stable resonance form has a carbon-oxygen double bond (neutral) and the less stable resonance form has a positive charge on carbon and a negative charge on oxygen. So the “resonance hybrid” has a small partial positive charge on carbon, because of that resonance form on the right. Now let’s add acid – say, H+ . The oxygen will go from “owning” a pair of electrons, to “sharing” it with the hydrogen. So it formally “loses” an electron to give a positively charged oxygen. (Watch out though: remember that “formal charge” doesn’t tell us about electron densities: electronegativity does. So even though there’s a “formal charge” of +1 on the oxygen, it’s still electron-rich compared to hydrogen and carbon) With me so far? If this isn’t clear, write me! If everything is OK, let’s keep going. Think about what this does to the resonance forms. Now, both resonance forms have a charge of +1 . This means that the right-hand resonance form ( Continue reading >>

Contrasting C- And O-atom Reactivities Of Neutral Ketone And Enolate Forms Of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones.

Contrasting C- And O-atom Reactivities Of Neutral Ketone And Enolate Forms Of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones.

Abstract The mechanisms of intramolecular cyclization of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones (1) under basic (DABCO and t-BuOK) and acidic (AcOH and TFA) conditions were investigated by means of experimental and computational methods. The ketone, enol, and enolate forms of 1 can afford different intramolecular cyclization products (2, 3, 4), depending on the conditions. The results of the reaction of 1 under basic conditions suggest intermediacy of neutral enol (DABCO) and anionic enolate (t-BuOK), while the results under acidic conditions (AcOH and TFA) indicate involvement of neutral ketones, which exhibit reactivities arising from both the oxygen lone-pair electrons (O atom reactivity) and carbon σ-electrons (C atom reactivity). The neutral enol in DABCO afforded 2H-azirine 4. On the other hand, the products (isoxazole 2 and oxazole 3) generated from the ketone form and from the enolate form are the same, but the reaction mechanisms are apparently different. The results demonstrate ambident-like reactivity of neutral ketone in the 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanone system. Continue reading >>

Contrasting C- And O-atom Reactivities Of Neutral Ketone And Enolate Forms Of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones

Contrasting C- And O-atom Reactivities Of Neutral Ketone And Enolate Forms Of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones

Abstract The mechanisms of intramolecular cyclization of 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanones (1) under basic (DABCO and t-BuOK) and acidic (AcOH and TFA) conditions were investigated by means of experimental and computational methods. The ketone, enol, and enolate forms of 1 can afford different intramolecular cyclization products (2, 3, 4), depending on the conditions. The results of the reaction of 1 under basic conditions suggest intermediacy of neutral enol (DABCO) and anionic enolate (t-BuOK), while the results under acidic conditions (AcOH and TFA) indicate involvement of neutral ketones, which exhibit reactivities arising from both the oxygen lone-pair electrons (O atom reactivity) and carbon σ-electrons (C atom reactivity). The neutral enol in DABCO afforded 2H-azirine 4. On the other hand, the products (isoxazole 2 and oxazole 3) generated from the ketone form and from the enolate form are the same, but the reaction mechanisms are apparently different. The results demonstrate ambident-like reactivity of neutral ketone in the 3-sulfonyloxyimino-2-methyl-1-phenyl-1-butanone system. Continue reading >>

Rotational Barriers In Aldehydes And Ketones Coordinated To Neutral Lewis Acids

Rotational Barriers In Aldehydes And Ketones Coordinated To Neutral Lewis Acids

Note: In lieu of an abstract, this is the article's first page. This user does not have a subscription to this publication. Please contact your librarian to recommend that your institution subscribe to this publication. Purchase temporary access to this content. Use your free ACS Member Universal Access (if available) Continue reading >>

Ketone

Ketone

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. They are found in several sugars and in compounds for medicinal use, including natural and synthetic steroid hormones. Molecules of the anti-inflammatory agent cortisone contain three ketone groups. Only a small number of ketones are manufactured on a large scale in industry. They can be synthesized by a wide variety of methods, and because of their ease of preparation, relative stability, and high reactivity, they are nearly ideal chemical intermediates. Many complex organic compounds are synthesized using ketones as building blocks. 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 (CH3COCH3), a liquid with a sweetish odour. Acetone is one of the few organic compounds that is infinitely soluble in water (i.e., soluble in all proportions); it also dissolves many organic compounds. For this reason—and because of its low boiling point (56 °C [132.8 °F]), which makes it easy to remove by evaporation when no longer wanted—it is one of the most important industrial solvents, being used in such products as paints, varnishes, resins, coatings, and nail-polish removers. The International Union of Pure and Applied Chemistry (IUPAC) name of a ketone is derived by selecting as the parent the longest chain of carbon atoms that contains the carbonyl group. The parent chain is numbered from the end that Continue reading >>

Water-promoted Organic Reactions. Michael Addition Of Nitroalkanes To Methylvinylketone Under Neutral Conditions

Water-promoted Organic Reactions. Michael Addition Of Nitroalkanes To Methylvinylketone Under Neutral Conditions

Nitromethane and nitroethane when diluted in water, under neutral conditions, react easily, without any catalyst, with Michael acceptors, such as methylvinylketone. The rate of the reaction is enhanced in sugar aqueous solutions. Graphical abstracts Water as solvent promotes the uncatalyzed Michael reaction of nitroalkanes with methylvinylketone; the rate is enhanced in sugar solutions. View more articles Continue reading >>

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