diabetestalk.net

Ketone Synthesis From Alkene

Synthesis: Ketone To Alkene Conversion With C-c Bond Formation

Synthesis: Ketone To Alkene Conversion With C-c Bond Formation

Ketones are converted to alkenes accompanied by carbon-carbon bond formation through the Wittig reaction. Alternatively, this same transformation can be accomplished through the addition of a Grignard reagent to the ketone followed by dehydration of the resulting alcohol. Evaluate the four reactions below as to their potential for producing the alkene depicted in the box. Continue reading >>

Ozonolysis

Ozonolysis

Index: Overview Acyclic Alkene Substitution Pattern Resonance in Ozone The Molozonide Reduction of the Ozonides Overview: Ozonolysis is the process by which ozone (O3) reacts with alkenes (olefins) to break the double bond and form two carbonyl groups. If the double bond of the alkene is substituted with hydrogen or carbon atoms, the carbonyl groups that are formed are either aldehydes or ketones. Acyclic alkenes form two carbonyl compounds while cyclic alkenes produce a single compound containing two carbonyl groups. As an analytical tool, ozonolysis reveals the substitution pattern of a double bond. Acting as a pair of chemical scissors, the reactive gas cuts the double bond and replaces it with oxygen atoms, i. e., carbonyl groups. However, ozonolysis does not afford information on the stereochemistry of the alkene if such stereochemistry existed originally. Thus, the generic, stereoisomeric alkenes 1 and 2 give rise to the same pair of carbonyl compounds. The astute reader will recognize that neither of these reactions is a balanced equation. Only two oxygen atoms (one equivalent of O2) is required to balance this reaction. The fate of the third oxygen atom will be considered later. Ozonolysis is also an important reaction from the synthetic perspective with compounds that have several functional groups. Because alkenes are nucleophilic and carbonyl groups are electrophilic, aldehydes and ketones can be stored as alkenes during synthetic reactions that are electrophilic. At the appropriate time, the alkene can be converted to the aldehyde or ketone when it is its turn to undergo electrophilic reactions. Acyclic Alkene Substitution Pattern: The substitution pattern of a double bond in an acyclic alkene can be ascertained by the number and type of carbonyl compounds t Continue reading >>

Preparation & Reactions Of Aldehydes And Ketones, Rho & Ror'

Preparation & Reactions Of Aldehydes And Ketones, Rho & Ror'

A couple of key points: Aldehydes and Ketones both contain a carbonyl group, but are also less reactive than acid chlorides. They do NOT react with organocopper reagents and weak hydride donors (as these weak reagents are involved in their own synthesis). The reactions are addition rather than substitution as there is no leaving group. They have one less bond to an electronegative atom than acid chlorides (no chlorine!). They can be formed through reduction of Acid Chloride: If an aromatic ring is being substituted then we must use friedel crafts acylation. For Acid Chloride to Aldehyde we use Bu3SnH as a source of weak Hydride ions which displace a Cl-. We do not use a more obvious source such as LiAlH4 as this will result in the over reduction of the aldehyde into a primary alcohol. For Acid Chloride to Ketone we use R’2CuLi as a source of nucleophilic R’ group. and via reactions with Alcohols: Simply, Primary alcohols lead to Aldehydes and secondary alcohols lead to Ketones when reacted with PCC. This is oxidation. Testing Laboratory Microbiology - Air Quality - Mold Asbestos - Environmental - Lead emsl.com and finally with Alkanes: Alkanes are just as simple as alcohols – just add O3 then PPh3 for an easy reaction! Simple alkenes lead to aldehydes and more complex lead to ketones. Synthesis Summary: In short: REDUCTION From Acid Chloride to Aldehyde – Bu3SnH (as a source of H-) From Acid Chloride to Ketone – R2CuLi (as a source of R) OXIDATION From Alcohol to Aldehyde/Ketone – PCC From Alkene to Aldehyde/Ketone – O3 then PPh3 – Reactions with Carbon Nucleophiles and Hydride Donors As mentioned earlier, aldehydes and ketones do not react with weak hydride donors (eh Bu3SnH) or organocopper reagents (eg R2CuLi) – they need more powerful reagents. The Continue reading >>

2 Departamento De Quãmica, Facultad Experimental De Ciencias, Universidad Del Zulia,

2 Departamento De Quãmica, Facultad Experimental De Ciencias, Universidad Del Zulia,

Reviews and Accounts ARKIVOC 2013 (i) 396-417 Page 396 © ARKAT-USA, Inc. Reagents for the synthesis of alkenes from carbonyl compounds: applications in the synthesis of terpenoid compounds William J. Vera, 1 Manuel S. Laya, 1 Po S. Poon, 1 Ajoy K. Banerjee, and Elvia V. Cabrera 2 1 Instituto Venezolano de Investigaciones CientÃficas (IVIC), Centro de QuÃmica, Apartado-21827, Caracas-1020A, Venezuela 2 Departamento de QuÃmica, Facultad Experimental de Ciencias, Universidad del Zulia, Maracaibo, Venezuela Email: [email protected] Abstract The carbon-carbon double bond has been introduced by replacing carbonyl group employing various reagents in several decalones and tetralones. The resulting unsaturated compounds have been utilized for the synthesis of natural products related to diterpenes triptolide, taxodione and sesquiterpenes, herbertene, cuauhtemone, warburganal, drim-8-en-7-one, occidol, mansonone F and biflorine. Keywords: Halide, tosylate, mesylate, alkene, dimethylformamide, 2,4-pentanediol Table of Contents 1. Introduction 2. Reagents for the Conversion of Carbonyl into Alkene 2.1. Lithium bromide (LiBr), lithium carbonate (Li2CO3) and dimethylformamide (DMF) 2.2. Thionyl chloride (SOCl2), phosphorus oxychloride (POCl3) and pyridine 2.3. Acid catalysed (p-toluenesulphonic acid, sulphuric acid, hydrochloric acid) dehydration 2.5. Grignard reagents (MeMgBr, Me2CHMgBr) 2.6. 2,4-Pentanediol and p-toluenesulfonic acid 3. Conclusions 4. Reference Reviews and Accounts ARKIVOC 2013 (i) 396-417 Page 397 © ARKAT-USA, Inc. 1. Introduction The formation of carbon-carbon double bond is of fundamental importance in organic synthesis because it allows the introduction of a wide variety of functional groups. As a result, many reactions and reagents have been develop Continue reading >>

Synthesis Of Α-cf3 Ketones From Alkenes And Electrophilic Trifluoromethylating Reagents By Visible-light Driven Photoredox Catalysis

Synthesis Of Α-cf3 Ketones From Alkenes And Electrophilic Trifluoromethylating Reagents By Visible-light Driven Photoredox Catalysis

Highlights • • Visible light photoredox trifluoromethylation of alkenes is performed. • An electrophilic trifluoromethylating reagent (Togni's reagent) was used. • Abstract α-Trifluoromethyl ketones are important fluorinated intermediates and products in chemical synthesis and medicinal development. Herein, visible light-catalyzed photoredox trifluoromethylation of 1-aryl-2-alkyl substituted alkenes using an electrophilic trifluoromethylating reagent to produce α-trifluoromethyl ketones is reported. Two possible pathways involving either a trifluoromethyl radical or a styrene radical cation are proposed and discussed. Graphical abstract Continue reading >>

Question: Wittig Reaction: Synthesis An Alkene ( Olefin) From The Reaction Of An Aldehyde Or A K...

Question: Wittig Reaction: Synthesis An Alkene ( Olefin) From The Reaction Of An Aldehyde Or A K...

Wittig Reaction: synthesis an alkene ( olefin) from the reaction of an aldehyde or a ketone with a phosphorous ylide ( phosphorane ). The ylide is produced from phoshonium salt with a base ( NaOH ). The alkene synthesized is trans-9-(2-phenylethenyl)anthracene. 1.) what is the overall chemical reaction? List all steps (step-by-step) with the compound names underneath. 2.) what is the Reaction Mechanism? List all steps (step-by-step) with the compound names underneath. Continue reading >>

Enolates With Aldehydes And Ketones

Enolates With Aldehydes And Ketones

Mannich Reaction This is a typical example of a Mannich reaction. It involves an enolizable aldehyde or ketone, a secondary amine, formaldehyde as its aqueous solution, and catalytic HCl. The product is an amino-ketone from the addition of one molecule each of formaldehyde and the amine to the ketone. Below are shown the various stages of the Mannich reaction. 'Click' the different stages to view 3D animations of the reactions: Step 1: Imine formation Step 2: Addition of imine salt to ketone The Mannich products can be converted to enones. Enones such as that shown below, with two hydrogen atoms at the end of the double bond are called exo-methylene compounds. Whilst they are very reactive, they cannot easily be made or stored. Click the image to view the 3D animation T. F. Cummings and J. R. Shelton, J. Org. Chem, 1960, 25, 419–423. H. G. O. Alvim, E. N. da Silva Júnior and B. A. D. Neto, RSC Adv., 2014, 4, 54282–54299. 621 Continue reading >>

Synthesis (4) – Reactions Of Alkenes

Synthesis (4) – Reactions Of Alkenes

In the last post on alkenes we covered the reactions of alkyl halides and it made out tiny little reaction map explode into a cascade. Here we’re really going to blow up our reaction map, because we’re going to talk about a second very important “hub” for synthesis – alkenes. If you haven’t already noticed…. there are a LOT of alkene reactions. Alkenes are a very versatile building block in organic chemistry, as I hope this post will make clear. This post is going to assume you’re familiar with these reactions and their products. We’re not going to go into mechanisms or other details here. The point is learning how to apply these reactions so that eventually we can plan syntheses that will take us from one functional group to another. If you need more background on these reactions by all means read this series of posts on alkenes. As we’ve said many times before, the vast majority of alkene reactions fall into the category of “addition reactions”. That is, we’re breaking a C-C π bond and forming two new bonds to carbon. The new bonds that form, of course, determine the functional group we will be creating. Beneath that, there is a second level of detail – the “regioselectivity” and “stereoselectivity” of the reaction, which you will also need to be familiar with – that will, alas, largely be ignored in our big-picture analysis in this post. The second category of alkene reactions is “oxidative cleavage”, which involves the cleavage of both C-C bonds and the formation of two new carbonyl [C=O] groups. Depending on conditions, C-H bonds directly attached to the sp2 hybridized carbons of the alkene can also be oxidized to C-OH . For the purposes of synthesis, we’ll largely be focusing on the new functional groups that are create Continue reading >>

Ozonolysis

Ozonolysis

In this video, we're going to look at the cleavage of alkenes using a reaction called ozonolysis. So over here on the left I have my generic alkene, and to that alkene we're going to add O3 in the first step, which is ozone. And in the second step, we're going to add DMS, which is dimethyl sulfide. And be careful because there are different regions you could add in the second step, so make sure to learn the one that your professor wants you to use. If you use it DMS, you're going to get to a mixture of aldehydes and or ketones for your product, depending on what is attached to your initial alkene. So let's start by looking at a dot structure for ozone. So over here on the left is a possible structure for ozone. And we can draw a resonant structure by taking these electrons and moving them in here to form a double bond between those two oxygens. And now it pushed these electrons in here off onto the oxygen on the left. So let's go ahead and draw the other resonant structure. So now I would have a double bond between my two oxygens on the right. The oxygen on the far right has two lone pairs of electrons around it now. The oxygen in the center still has a lone pair of electrons on it, and the oxygen on the far left now has three lone pairs of electrons on it. So the oxygen on the far left now has a negative 1 formal charge, and the oxygen on the top here still has a plus 1 formal charge. And so those are our two resonant structures. Remember that the actual molecule is a hybrid of these two resonant structures. So let's go ahead and pick one of those resonant structures. I'm just going to take the one on the right. So let me just go ahead and redraw the resonant structure on the right. And so we're going to do the one that has the negative charge on the oxygen on the far Continue reading >>

Synthesis Of Carboxylic Acids

Synthesis Of Carboxylic Acids

There are many possible synthetic pathways that yield carboxylic acids. Some of these are further discussed below. Alcohols and aldehydes may be oxidized into carboxylic acids. Alkenes may be converted into carboxylic acid through oxidative cleavage of the double bond with neutral or acid permanganate, for instance. However, the alkene must contain at least one hydrogen located at the double bond, otherwise only ketones are formed. The intermediate stage of an alkene's oxidative cleavage with permanganate is a 1,2-diol. If the alkene is not water-soluble, potassium permanganate can be made soluble in an organic solvent by the application of the crown ether (a cyclic polyether) 18-crown-6. 18-crown-6 complexes the potassium ion in its center, while its periphery is non-polar. As a result, potassium ions can be dissolved in an organic solvent, such as benzene, and the negatively charged permangnate ion is, thus, forced to dissolve, as well. The reactivity of permanganate ions that are dissolved in such a way is much higher than that of permangante ions in aqueous solution, as they are not solvated. Many alkenes may be converted into carboxylic acids through ozonization and subsequent oxidative workup. In a haloform reaction with iodine, bromine, or chlorine, methyl ketones are converted into the corresponding carboxylic acid and haloform. A Gringard reaction with carbon dioxide yields a carboxylate whose carbon chain contains exactly one carbon more than the alkyl halide applied. Hydrolysis of the carboxylate leads to the formation of the carboxylic acid. The reaction is diversely applicable and proves to be an easy source of many carboxylic acids. 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 >>

Wacker Oxidation

Wacker Oxidation

The Wacker oxidation refers generally to the transformation of a terminal or 1,2-disubstituted alkene to a ketone through the action of catalytic palladium(II), water, and a co-oxidant. Variants of the reaction yield aldehydes, allylic/vinylic ethers, and allylic/vinylic amines. Because of the ease with which terminal alkenes may be prepared and the versatility of the methyl ketone group installed by the reaction, the Wacker oxidation has been employed extensively in organic synthesis.[1] The stoichiometric conversion of ethylene to acetaldehyde by an acidic, aqueous solution of PdCl2 was discovered over a century ago,[2] but fifty years passed between the discovery of this reaction and the development of a catalytic method. In 1959, researchers at Wacker Chemie reported that a similar transformation takes place in an aqueous, acidic solution of catalytic PdCl2 and a stoichiometric amount of CuCl2 through which oxygen is bubbled (Eq. 1).[3] (1) Since this initial report, the Wacker process has been widely applied in organic synthesis and has been extended to other classes of substrates and products. To encourage mixing of the organic reactants with the aqueous phase, a co-solvent is generally employed along with water. Dimethylformamide (DMF) is a common choice; when DMF is used as a co-solvent with a stoichiometric amount of CuCl under balloon pressure of oxygen, the reaction is called the "Tsuji-Wacker oxidation."[4] Applications of the Wacker oxidation to organic synthesis typically involve the installation of a methyl ketone moiety, which may subsequently undergo nucleophilic addition or deprotonation to form an enolate. Mechanism and Stereochemistry The mechanism of the Wacker oxidation has been studied both experimentally and theoretically (Eq. 2). The first step Continue reading >>

Catalytic Addition Of Simple Alkenes To Carbonyl Compounds Using Group 10 Metals

Catalytic Addition Of Simple Alkenes To Carbonyl Compounds Using Group 10 Metals

Go to: 1 Introduction Functionalization of simple alkenes has long been a focus in organic chemistry, largely because alkenes are one of the most readily available classes of functional groups.1 Several indispensable catalytic transformations utilize olefins, such as Ziegler-Natta polymerization, the Wacker oxidation, hydroformylation, epoxidation, hydrometallation, and dihydroxylation, and thereby provide access to several important classes of other functional groups.2–4 Similarly important technologies are those that functionalize olefins while leaving the olefin intact, such as olefin cross-metathesis and the Heck reaction.5,6 The resulting functionalized alkenes serve as versatile building blocks for subsequent manipulations. Historically, the most direct methods for the synthesis of allylic and homoallylic alcohols from alkenes and carbonyl compounds are the Prins reaction and carbonyl-ene reaction (Scheme 1).7,8 These reactions generally form a new carbon–carbon bond at the less substituted carbon of the alkene. Typically, electron-rich alkenes, such as 1,1-disubstituted or trisubstituted olefins, react effectively with small and electron-deficient enophiles, including formaldehyde and glyoxylates. These processes proceed with heating and typically benefit from significant rate enhancement under the action of Lewis acid catalysts. Considerably less attention has been paid to extending the substrate scope to include electron-rich and sterically demanding aldehydes or less nucleophilic alkenes such as α-olefins.9–12 The typical carbonyl used in the intermolecular Prins reaction to make allylic alcohols is also largely limited to formaldehyde. In short, these traditional technologies are effective for only a small subset of the plethora of possible coupling pa Continue reading >>

Synthesis Of Alkenes From Ketones Via Arylsulphonyl-hydrazones; Mechanistic Views; The Organic Chemistry Notebook Series, A Didactical Approach, N27

Synthesis Of Alkenes From Ketones Via Arylsulphonyl-hydrazones; Mechanistic Views; The Organic Chemistry Notebook Series, A Didactical Approach, N27

ARTÍCULOS ORIGINALES José A. Bravo1*, José L. Vila2 1 Department of Chemistry, Laboratorio de Fitoquímica, Instituto de Investigaciones en Productos Naturales IIPN, Universidad Mayor de San Andrés UMSA, P.O. Box 303, Calle Andrés Bello s/n, Ciudad Universitaria Cota Cota, Phone 59122792238, La Paz, Bolivia, [email protected] *Corresponding author: [email protected] 2Department of Chemistry, Laboratorio de Síntesis y Hemisíntesis, Instituto de Investigaciones en Productos Naturales IIPN, Universidad Mayor de San Andrés UMSA, P.O. Box 303, Calle Andrés Bello s/n, Ciudad Universitaria Cota Cota, Phone 59122795878, La Paz, Bolivia, [email protected] Abstract This is the seventh chapter in the series published by the same authors: "The Organic Chemistry Notebook Series, a Didactical Approach". The aim of this series of studies is to help students to have a graphical view of organic synthesis reactions of diverse nature. Here we describe the mechanistic views of the synthesis of alkenes from ketones via arylsulphonylhydrazones. These methods employ aliphatic and alicyclic ketones with one a-hydrogen, that react along with toluene-p-sulphonylhydrazones and two equivalents of an alkyl-lithium or lithium diisopropylamide. The mechanism views for the transformation of pinacolone into 3,3-dimethyl-1-butene are proposed. The formation of 3-phenylpropene using phenylacetone is explained step by step. An approach is made on the obtaining of alkenes from ketones using derived enol ethers or esters by means of reductive excision or by means of coupling with organocuprates. We have used various series of reactions reviewed by W. Carruthers in 'Some modern methods of organic synthesis', and we have proposed didactical and mechanistic views for them. This theme is included Continue reading >>

Synthesis Of Ketones

Synthesis Of Ketones

Like aldehydes, ketones can be prepared in a number of ways. The following sections detail some of the more common preparation methods: the oxidation of secondary alcohols, the hydration of alkynes, the ozonolysis of alkenes, Friedel‐Crafts acylation, the use of lithium dialkylcuprates, and the use of a Grignard reagent. The oxidation of secondary alcohols to ketones may be carried out using strong oxidizing agents, because further oxidation of a ketone occurs with great difficulty. Normal oxidizing agents include potassium dichromate (K 2Cr 2O 7) and chromic acid (H 2CrO 4). The conversion of 2‐propanol to 2‐propanone illustrates the oxidation of a secondary alcohol. The addition of water to an alkyne leads to the formation of an unstable vinyl alcohol. These unstable materials undergo keto‐enol tautomerization to form ketones. The hydration of propyne forms 2‐propanone, as the following figure illustrates. When one or both alkene carbons contain two alkyl groups, ozonolysis generates one or two ketones. The ozonolysis of 1,2‐dimethyl propene produces both 2‐propanone (a ketone) and ethanal (an aldehyde). Friedel‐Crafts acylations are used to prepare aromatic ketones. The preparation of acetophenone from benzene and acetyl chloride is a typical Friedel‐Crafts acylation. The addition of a lithium dialkylcuprate (Gilman reagent) to an acyl chloride at low temperatures produces a ketone. This method produces a good yield of acetophenone. Hydrolysis of the salt formed by reacting a Grignard reagent with a nitrile produces good ketone yields. For example, you can prepare acetone by reacting the Grignard reagent methyl magnesium bromide (CH 3MgBr) with methyl nitrile (CH 3C&tbond;N). Continue reading >>

More in ketosis