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Synthesis Of Ketones From Carboxylic Acids

Preparation Of Ketones From The Reaction Of Organolithium Reagents With Carboxylic Acids

Preparation Of Ketones From The Reaction Of Organolithium Reagents With Carboxylic Acids

Abstract The reaction of organolithium reagents and carboxylic acids constitutes a simple general method for the synthesis of ketones. This preparative route is the method of choice for direct conversion of carboxylic acid to ketones. It is the purpose of this chapter to evaluate critically the scope and limitations of this reaction and to recommend optimal conditions for its applications. The reaction of organolithium reagents with carboxylic acid is limited to the preparation of acyclic ketones. Although the objective of this reaction, the formation of unsymmetrical ketones, the method is clearly applicable to the synthesis of symmetrical ketones. Two different routes are possible and are discussed. To date, the reaction has been applied only to the preparation of monoketones. Continue reading >>

Reactions Of Carboxylic Acids

Reactions Of Carboxylic Acids

Reactions with Organolithium Compounds and Metal Hydrides Carboxylic acids are both Brønsted acids and Lewis acids. Their Lewis acid qualities may be attributed not only to the acidic proton, but also to the electrophilic carbonyl carbon, as they are both able to act as an electron acceptor. However, if a carboxylic acid is treated with an organolithium compound, an acid-base reaction first takes place. In such a reaction, the acidic proton is abstracted by the organolithium compound's alkyl or aryl anion, as alkyl and aryl anions are extremely strong bases. Nevertheless, alkyl and aryl anions are also efficient nucleophiles. As a result, the carbonyl carbon of the carboxylate anion which is formed in the first reaction step is nucleophilically attacked by an additional alkyl or aryl anion. The result of a subsequent hydrolysis is the protonation of the dianion. This yields a geminal diol and lithium hydroxide. The geminal diol represents a ketone's hydrate. Thus, it spontaneously eliminates water to yield the ketone. The reaction may be carried out with primary, secondary, and tertiary alkyllithium compounds, as well as with aryllithium compounds. In order to obtain a ketone in this reaction, two equivalents of the organolithium compound to one equivalent of carboxylic acid must be applied, as the first equivalent is consumed by the acid-base reaction which cannot be prevented. Due to the negative charge of the carboxylate anion, the electrophilicity of a ketone's carbonyl carbon is comparatively higher. Nevertheless, the ketone does not react with the organolithium compound, as it is not formed until the workup with water through which the remaining organolithium compound is also hydrolyzed. In contrast with lithium aluminum hydride, carboxylic acids are reduced to t Continue reading >>

Aldehydes, Ketones, Carboxylic Acids, And Esters

Aldehydes, Ketones, Carboxylic Acids, And Esters

Learning Objectives By the end of this section, you will be able to: Describe the structure and properties of aldehydes, ketones, carboxylic acids and esters Another class of organic molecules contains a carbon atom connected to an oxygen atom by a double bond, commonly called a carbonyl group. The trigonal planar carbon in the carbonyl group can attach to two other substituents leading to several subfamilies (aldehydes, ketones, carboxylic acids and esters) described in this section. Aldehydes and Ketones Both aldehydes and ketones contain a carbonyl group, a functional group with a carbon-oxygen double bond. The names for aldehyde and ketone compounds are derived using similar nomenclature rules as for alkanes and alcohols, and include the class-identifying suffixes –al and –one, respectively: In an aldehyde, the carbonyl group is bonded to at least one hydrogen atom. In a ketone, the carbonyl group is bonded to two carbon atoms: In both aldehydes and ketones, the geometry around the carbon atom in the carbonyl group is trigonal planar; the carbon atom exhibits sp2 hybridization. Two of the sp2 orbitals on the carbon atom in the carbonyl group are used to form σ bonds to the other carbon or hydrogen atoms in a molecule. The remaining sp2 hybrid orbital forms a σ bond to the oxygen atom. The unhybridized p orbital on the carbon atom in the carbonyl group overlaps a p orbital on the oxygen atom to form the π bond in the double bond. Like the C=O bond in carbon dioxide, the C=O bond of a carbonyl group is polar (recall that oxygen is significantly more electronegative than carbon, and the shared electrons are pulled toward the oxygen atom and away from the carbon atom). Many of the reactions of aldehydes and ketones start with the reaction between a Lewis base and Continue reading >>

A New Practical Ketone Synthesis Directly From Carboxylic Acids: First Application Of Coupling Reagents In Palladium Catalysis

A New Practical Ketone Synthesis Directly From Carboxylic Acids: First Application Of Coupling Reagents In Palladium Catalysis

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On The Reaction Between Methyllithium And Carboxylic Acids

On The Reaction Between Methyllithium And Carboxylic Acids

In 1933, Gilman showed that on carbonation phenyllithium yielded 70% benzophenone and no benzoic acid, which is the main product on carbonation of the corresponding magnesium compound. They found that the reason for the high yield of ketone was the higher reactivity of the organolithium compound. If an aryllithium compound was allowed to react with carbon dioxide at temperatures between -50°C and -80°C the following reaction occurred: RLi + CO2 RCOOLi At a higher temperature (room temperature) another reaction took place. To the lithium salt of ArCOOH was added one mole of aryllithium, and a dilithium salt of a dihydroxymethane was obtained, which on hydrolysis yielded a ketone in accordance with the following general reaction: Only in one case, hitherto, has any comparison been made between the use of the free acid or its lithium salt: In the case of benzophenone Gilman and van Ess have made two syntheses. One started with the lithium benzoate, which was allowed to react with one mole of phenyllithium, and was found to give a 70% yield of ketone and no tertiary alcohol; the second experiment started with benzoic acid and two moles of phenyllithium and yielded 37.2% of ketone and 14.1% of triphenylcarbinol. Two possible explanations are given for the formation of the tertiary alcohol. The first is that benzoic acid is dehydrated by phenyllithium to give benzoic anhydride. This would react with one mole of phenyllithium to give lithium benzoate and "free" benzophenone, which would enter the ordinary reaction of a ketone yielding triphenylcarbinol: 2 C6H5COOH + 2 C6H5Li (C6H5CO)2O (C6H5CO)2O + C6H5Li (C6H5)2CO + C6H5COOLi (C6H5)2CO + C6H5Li (C6H5)3COLi -> (C6H5)3COH Another explanation is suggested, in which the phenyllithium is supposed to be added directly to the carb Continue reading >>

Reactions At The Α-carbon

Reactions At The Α-carbon

Many aldehydes and ketones were found to undergo electrophilic substitution at an alpha carbon. These reactions, which included halogenation, isotope exchange and the aldol reaction, take place by way of enol tautomer or enolate anion intermediates, a characteristic that requires at least one hydrogen on the α-carbon atom. In this section similar reactions of carboxylic acid derivatives will be examined. Formulas for the corresponding enol and enolate anion species that may be generated from these derivatives are drawn in the following diagram. Acid-catalyzed alpha-chlorination and bromination reactions proceed more slowly with carboxylic acids, esters and nitriles than with ketones. This may reflect the smaller equilibrium enol concentrations found in these carboxylic acid derivatives. Nevertheless, acid and base catalyzed isotope exchange occurs as expected; some examples are shown in equations #1 and #2 below. The chiral alpha-carbon in equation #2 is racemized in the course of this exchange, and a small amount of nitrile is hydrolyzed to the corresponding carboxylic acid. Acyl halides and anhydrides are more easily halogenated than esters and nitriles, probably because of their higher enol concentration. This difference may be used to facilitate the alpha-halogenation of carboxylic acids. Thus, conversion of the acid to its acyl chloride derivative is followed by alpha-bromination or chlorination, and the resulting halogenated acyl chloride is then hydrolyzed to the carboxylic acid product. This three-step sequence can be reduced to a single step by using a catalytic amount of phosphorus tribromide or phosphorus trichloride, as shown in equation #3. This simple modification works well because carboxylic acids and acyl chlorides exchange functionality as the reactio Continue reading >>

Preparation Of Alcohols Using Lialh4

Preparation Of Alcohols Using Lialh4

In the last video, we saw that sodium borohydride will reduce aldehydes or ketones to form primary or secondary alcohols. And if we look at this general reaction, this is either an aldehyde or a ketone over here. If we add lithium aluminum hydride in the first step and then a source of protons in the second step-- which is water-- we will form either a primary or a secondary alcohol, depending on our starting materials. So in that respect, lithium aluminum hydride will react in the same way as sodium borohydride. However, sodium borohydride will only reduce aldehydes or ketones. It won't reduce carboxylic acids or esters. And that's what lithium aluminum hydride does. So we can see that-- if this is an OH right here-- that would be a carboxylic acid functional group. And if we take off the H and put in an alkyl group in our prime group there, we would have an ester. So lithium aluminum hydride, not only reduces aldehydes and ketones, it also reduces carboxylic acids and esters since it's more reactive, which is also why we have to separate these two. We can't have water in the same reaction vessel as our lithium aluminum hydride because it will react with that faster. And so once again, our product will depend on what our starting material is. So the mechanism for the reduction of aldehydes or ketones with lithium aluminum hydride is just like the one for sodium borohydride. So we'll move on to a mechanism for the reduction of an ester. So let's go ahead and do that. So let's start with an ester down here. So we have our carbonyl. Like that. So we'll put in our lone pairs. And down here, we have our R prime group. Like that. So there's our ester. And we add lithium aluminum hydride in excess. So in terms of molar equivalence, let's go ahead and put lithium aluminum hydr Continue reading >>

Aldehyde, Ketones And Carboxylic Acids

Aldehyde, Ketones And Carboxylic Acids

Aldehyde and  Ketones Preparation of Aldehydes  a. Oxidation of primary alcohols a) Oxidation of Secondary alcohols: a)  Aldol condensation Aldehydes and ketones having alpha hydrogen atom: Aldehydes and ketones having  no alpha hydrogen atom:   Esters having a-hydrogen on treatment with a strong base e.g. C2H5ONa. Undergo self condensation to produce b-keto esters. This reaction is Claisen Condensation. d)   Reformatsky Reaction This is the reaction of a-haloester, usually an a-bromoester with an aldehyde or ketone in the presence of Zinc metal to produce b-hydroxyester. e) Pinacol-pinacolone Rearrangement The acid catalysed rearrangement of 1,2 diols (Vicinal diols) to aldehydes or ketones with the elimination of water is known as pinacol pinacolone rearrangement. Aldehydes and Ketones react with phosphorus Ylides to yield alkenes and triphenyl phosphine oxide. An Ylide is a neutral molecule having a negative carbon adjacent to a positive hetero atom. Phosphorus ylides are also called phosphoranes. Preparation of Ylides Above things happens in BVO (Bayer Villiger oxidation). Reagents are either per acetic acid or perbenzoic acid or pertrifluoroacetic acid or permonosulphuric acid. e)   Addition of cyanide h)   Addition of Alcohols; Acetal Formation In H3O+, RCHO is regenerated because acetals undergo acid catalyzed cleavage much more easily than do ethers. Since acetals are stable in neutral or basic media, they are used to protect the – CH = O group. All aldehydes can be made to undergo the Cannizzaro reaction by treatment with aluminium ethoxide. Under these conditions the acids and alcohols are combined as the ester, and the reaction is then known as the Tischenko reaction; eg, acetaldehyde gives ethyl acetate, and propionaldehyde gives propyl propi Continue reading >>

Organic Chemistry/ketones And Aldehydes

Organic Chemistry/ketones And Aldehydes

Aldehydes () and ketones () are both carbonyl compounds. They are organic compounds in which the carbonyl carbon is connected to C or H atoms on either side. An aldehyde has one or both vacancies of the carbonyl carbon satisfied by a H atom, while a ketone has both its vacancies satisfied by carbon. 3 Preparing Aldehydes and Ketones Ketones are named by replacing the -e in the alkane name with -one. The carbon chain is numbered so that the ketone carbon, called the carbonyl group, gets the lowest number. For example, would be named 2-butanone because the root structure is butane and the ketone group is on the number two carbon. Alternatively, functional class nomenclature of ketones is also recognized by IUPAC, which is done by naming the substituents attached to the carbonyl group in alphabetical order, ending with the word ketone. The above example of 2-butanone can also be named ethyl methyl ketone using this method. If two ketone groups are on the same structure, the ending -dione would be added to the alkane name, such as heptane-2,5-dione. Aldehydes replace the -e ending of an alkane with -al for an aldehyde. Since an aldehyde is always at the carbon that is numbered one, a number designation is not needed. For example, the aldehyde of pentane would simply be pentanal. The -CH=O group of aldehydes is known as a formyl group. When a formyl group is attached to a ring, the ring name is followed by the suffix "carbaldehyde". For example, a hexane ring with a formyl group is named cyclohexanecarbaldehyde. Aldehyde and ketone polarity is characterized by the high dipole moments of their carbonyl group, which makes them rather polar molecules. They are more polar than alkenes and ethers, though because they lack hydrogen, they cannot participate in hydrogen bonding like Continue reading >>

(cf3co)2o/cf3so3h-mediated Synthesis Of 1,3-diketones From Carboxylic Acids And Aromatic Ketones

(cf3co)2o/cf3so3h-mediated Synthesis Of 1,3-diketones From Carboxylic Acids And Aromatic Ketones

Go to: Results and Discussion Initially, an unusual transformation of the β-phenylpropionic acids was observed by us in a TFAA/TfOH/CH2Cl2 system (Table 1), which gave the impulse for this research. Surprisingly, it turned out that β-phenylpropionic acid (1a) in a TFAA/CH2Cl2 medium in the presence of TfOH (0.25 equiv, Table 1, entry 1) gave 2-(β-phenylpropionyl)-1-indanone (3а) in 51% yield as the major product, even though we expected 1-indanone (2а, <2%). When 0.5 equiv of TfOH was applied, 3а and 2a were obtained in 75 and 16% yield, respectively (Table 1, entry 2). Evidently, in this reaction, 1-indanone (2а), which was initially formed as the result of an intramolecular cyclization of 1a, underwent a further acylation with the formation of 1,3-diketone 3a. In contrast, γ-phenylbutanoic acid (1c) was quantitatively transformed only to the tetralone 2с (Table 1, entries 10 and 11). The acid-catalyzed cyclization of 3-arylpropanoic and 4-arylbutanoic acids to 1-indanones and 1-tetralones is well-known [12–18], but it appears that the further acylation and β-diketone formation has not been reported yet. While the use of acyl trifluoroacetates, generated in situ from a carboxylic acid and TFAA, for the aromatic acylation catalyzed by acid (H3PO4 [19–22] or TfOH [23–25]) has been reported, the 1,3-diketone formation has not been observed yet. We concluded that in the work of reference [25], an apparently larger quantity of the super acidic TfOH was employed (4 equiv vs 0.25–1.5 equiv in our work), which possibly slowed down the reaction of ketone acylation. This is corroborated in the case of phenylpropionic acid 1а. Here, the yield of the diketone 3a decreased with an increase of the quantity of TfOH, whereas the yield of 1-indanone (2a) increased an Continue reading >>

Synthesis Of Aldehydes, Ketones, And Carboxylic Acids From Lower Carbonyl Compounds By C-c Coupling Reactions

Synthesis Of Aldehydes, Ketones, And Carboxylic Acids From Lower Carbonyl Compounds By C-c Coupling Reactions

© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to criminal prosecution. This applies in particular to photostat reproduction, copying, cyclostyling, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage. The methodology for the preparation of aldehydes, ketones, and carboxylic acids or their derivatives from lower carbonyl compounds by carbon-carbon bond forming reactions is reviewed. The material is presented according to the number of carbon atoms (1, 2, 3, or 4) that separate the carbonyl or acyl group, added during the carbon-carbon bond formation, from the original electrophilic center. 1. Introduction 2. Aldehydes and Ketones by One Carbon Elongations 2.1. Addition of Masked Acyl Anions 2.2. Reductive Nucleophilic Acylation 2.3. Nucleophilic Acylation Followed by Additional Carbonyl Elaboration 3. Carboxylic Acids or Their Derivatives by One Carbon Elongations 3.1. Addition of Masked Carboxyl Anions 3.2. Reductive Nucleophilic Carboxylation 3.3. Nucleophilic Carboxylation Followed by Additional Carbonyl Elaboration 4. Aldehydes and Ketones by Two Carbon Elongations 4.1. Aldol Condensation and Related Reactions 4.2. Wittig and Other Olefination Reactions 5. Carboxylic Acids or Their Derivatives by Two Carbon Elongations 5.1. Addition of Enolates of Carboxylic Acid Derivatives 5.2. Reaction with Ketene and Related Compounds 5.3. Wittig and Ot Continue reading >>

The Haloform Reaction: Conversion Of Methyl Ketones To Carboxylic Acids

The Haloform Reaction: Conversion Of Methyl Ketones To Carboxylic Acids

So I understand that the haloform reaction when using Iodine provides a nifty way to identify methyl ketones because the LG ‘CI3 precipates as a yellow solid in the form of Iodoform; I also understand that secondary methyl alcohols are oxidized by I2 in a radical-led oxidation rxn to a methyl ketone, which obviously goes through a subsequent reaction with I2. However, why do primary alcohols such as ethanol or propanol not react with I2? Would methanol react? My book does not expand anymore than just that I2 will react with methyl ketones and secondary methyl alcohols. Thanks! James Organic Chemistry 2 builds on the concepts from Org 1 and introduces a lot of new reactions. Here is an index of posts for relevant topics in Organic Chemistry 2: [Hint – searching for something specific? Try CNTRL-F] General Posts About Organic Chemistry 2 Oxidation And Reduction Alcohols, Ethers, And Epoxides Conjugation, Dienes and Pericyclic Reactions Aromaticity and Aromatic Reactions Aldehydes and Ketones Carboxylic Acid Derivatives General Posts Concerning Organic Chemistry 2 Oxidation And Reduction Alcohols, Epoxides, And Ethers Alcohols (1) Nomenclature And Properties How To Make Alcohols More Reactive Alcohols (3) Acidity And Basicity The Williamson Ether Synthesis Williamson Ether Synthesis: Planning Synthesis of Ethers (2) – Back To The Future! Ether Synthesis Via Alcohol And Acid Cleavage Of Ethers With Acid Epoxides – The Outlier Of The Ether Family Opening Of Epoxides With Acid Opening Of Epoxides With Base Making Alkyl Halides From Alcohols Tosylates And Mesylates PBr3 And SOCl2 Elimination Reactions Of Alcohols Elimination Of Alcohols To Alkenes With POCl3 Alcohol Oxidation: “Strong” And “Weak” Oxidants Demystifying Alcohol Oxidations Intramolecular Reactions Continue reading >>

Ketone

Ketone

Not to be confused with ketone bodies. Ketone group Acetone In chemistry, a ketone (alkanone) /ˈkiːtoʊn/ is an organic compound with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents. Ketones and aldehydes are simple compounds that contain a carbonyl group (a carbon-oxygen double bond). They are considered "simple" because they do not have reactive groups like −OH or −Cl attached directly to the carbon atom in the carbonyl group, as in carboxylic acids containing −COOH.[1] Many ketones are known and many are of great importance in industry and in biology. Examples include many sugars (ketoses) and the industrial solvent acetone, which is the smallest ketone. Nomenclature and etymology[edit] The word ketone is derived from Aketon, an old German word for acetone.[2][3] According to the rules of IUPAC nomenclature, ketones are named by changing the suffix -ane of the parent alkane to -anone. The position of the carbonyl group is usually denoted by a number. For the most important ketones, however, traditional nonsystematic names are still generally used, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names,[4] although some introductory chemistry textbooks use systematic names such as "2-propanone" or "propan-2-one" for the simplest ketone (CH3−CO−CH3) instead of "acetone". The common 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 alphabetically. 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 th Continue reading >>

B.r.s.m. When All You Have Is A Hammer Everything Looks Like A Nail

B.r.s.m. When All You Have Is A Hammer Everything Looks Like A Nail

A bit of a lack of exciting syntheses so far this week, so here's some methodology and random reflections and recollections. I don't mind that we don't get told the whole truth as undergraduates, because most of us can't handle the truth (well, not all of it). I appreciate that trying to convey even the basic concepts of organic synthesis to a large room full of people of mixed abilities, attention spans and interest levels in a reasonable amount of time is hard. I realise that only a tiny percentage of students on any given organic chemistry course will ever pursue the subject to a level where the simplifications they're taught in their first few years cause them much trouble. One of the earliest things I remember from undergraduate lectures on carbonyl chemistry is being told that Grignard reagents don't add to carboxylic acids, and that ketones (or tertiary alcohols) can't be made this way. The reason for this is simple - Grignards, like most nucleophilic organometallic reagents, are also strong bases so they deprotonate the acid and are then unable to attack the resulting anion. This property of carboxylic acids can be useful as it can be used to protect them from harm during a synthetic sequence (and is one of the reasons that carboxylic acids are just about the only carbonyl group to survive the Birch reduction). I'd gone on to assume that as carboxylic acids don't react with Grignards that they'd also be inert to all other organometallic reagents - organolithiums, cuprates etc. for exactly the same reason. That's what we organic chemists do, right? Rather than memorise everything we try and extrapolate reactivities of similar looking reagents. Well, last week I learned that actually Grignards are more of an exception than a general case, and that actually both or Continue reading >>

Synthesis Of Aldehydes, Ketones And Carboxylic Acids By Selective Oxidations Of Alcohols Using A Polypyridyl Complex Of Ruthenium(iv)

Synthesis Of Aldehydes, Ketones And Carboxylic Acids By Selective Oxidations Of Alcohols Using A Polypyridyl Complex Of Ruthenium(iv)

Electrocatalytic oxidations of alcohols were carried out using the complex [Ru(trpy)(bpy)0]2+. Primary aliphatic alcohols were oxidized to their respective aldehydes, secondary aliphatic and aromatic alcohols to the correspondent ketones and allyl and benzyl alcohols to their carboxylic acids. Controlling the number of coulombs passed through the solutions one could obtain aldehydes in good yields from the benzyl alcohols. Continue reading >>

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