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Ketones Chemistry

Ketone

Ketone

Previous (Kermit Roosevelt, Jr.) Next (Key (music)) A ketone (pronounced as key tone) is either the functional group characterized by a carbonyl group (O=C) linked to two other carbon atoms or a chemical compound that contains this functional group. A ketone can be generally represented by the formula: A carbonyl carbon bonded to two carbon atoms distinguishes ketones from carboxylic acids, aldehydes, esters, amides, and other oxygen-containing compounds. The double-bond of the carbonyl group distinguishes ketones from alcohols and ethers. The simplest ketone is acetone (also called propanone). Mold Test Kits Easy to Use, Fast Results Available Interpretive Lab Report moldtesting.com The carbon atom adjacent to a carbonyl group is called the α-carbon. Hydrogens attached to this carbon are called α-hydrogens. In the presence of an acid catalyst the ketone is subjected to so-called keto-enol tautomerism. The reaction with a strong base gives the corresponding enolate. A diketone is a compound containing two ketone groups. Nomenclature In general, ketones are named using IUPAC nomenclature by changing the suffix -e of the parent alkane to -one. For common ketones, some traditional names such as acetone and benzophenone predominate, and these are considered retained IUPAC names,[1] although some introductory chemistry texts use names such as propanone. Oxo is the formal IUPAC nomenclature for a ketone functional group. However, other prefixes are also used by various books and journals. For some common chemicals (mainly in biochemistry), keto or oxy is the term used to describe the ketone (also known as alkanone) functional group. Oxo also refers to a single oxygen atom coordinated to a transition metal (a metal oxo). Physical properties A carbonyl group is polar. This ma Continue reading >>

Ketone Definition

Ketone Definition

Ketone Definition A ketone is a compound containing a carbonyl functional group bridging two groups of atoms. The general formula for a ketone is RC(=O)R' where R and R' are alkyl or aryl groups. IUPAC ketone functional group names contain "oxo" or "keto". Ketones are named by changing the -e on the end of the parent alkane name to -one. Examples: Acetone is a ketone. The carbonyl group is connected to the alkane propane, therefore the IUPAC name for acetone would be propanone. Continue reading >>

Nomenclature Of Aldehydes & Ketones

Nomenclature Of Aldehydes & Ketones

Aldehydes and ketones contain the carbonyl group. Aldehydes are considered the most important functional group. They are often called the formyl or methanoyl group. Aldehydes derive their name from the dehydration of alcohols. Aldehydes contain the carbonyl group bonded to at least one hydrogen atom. Ketones contain the carbonyl group bonded to two carbon atoms. 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, 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. Naming Aldehydes The IUPAC system of nomenclature assigns a characteristic suffix -al to aldehydes. 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 always is given the #1 location position in numbering and it is not necessary to include it in the name. There are several simple carbonyl containing compounds which have common names which are retained by IUPAC. Also, there is a common method for naming aldehydes and ketones. For aldehydes common parent chain names, similar to those used for carboxylic acids, are used and the suffix –aldehyde is added to the end. In common names of aldehydes, carbon atoms near the carbonyl group are often designated by Greek letters. The atom adjacent to the carbonyl function is alpha, the next removed is beta and so on. If the aldehyde moiety (-CHO) is attached to a ring the suffix –carbaldehyde is added to the name of the ring. The carbon attached to this moiety will get the #1 location number in naming the ring. Aldehydes take their name Continue reading >>

Synthesis Of Ketones By Oxidation Of Alkenes

Synthesis Of Ketones By Oxidation Of Alkenes

Name Reactions Recent Literature The synergistic effect of photocatalysis and proton-reduction catalysis enables an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate. G. Zhang, X. Hu, C.-W. Chiang, H. Yi, P. Pei, A. K. Singh, A. Lei, J. Am. Chem. Soc., 2016, 138, 12037-12040. Utilizing the full potential of IBX, a mild, selective, and facile method enables a direct conversion of olefins into the corresponding α-bromo ketones in the presence of 1.1 equivalents each of o-iodoxybenzoic acid and tetraethylammonium bromide. S. S. Deshmukh, K. H. Chaudhari, K. G. Akamanchi, Synlett, 2011, 81-83. In a Co-catalyzed reaction for the construction of 1,4-dicarbonyls, a cascade organocobalt addition/trapping/Kornblum-DeLaMare rearrangement were involved. The reaction offers easy availability of starting materials, wide substrate scope, high functionality tolerance, and operational simplicity. F. Zhang, P. Du, J. Chen, H. Wang, Q. Luo, X. Wan, Org. Lett., 2014, 16, 1932-1935. Oxidative ring expansion of methylenecyclopropanes with CAN under oxygen atmosphere was investigated. A facile conversion affording 2,2-diarylcyclobutanones occurred in good yields. V. Nair, T. D. Suja, K. Mohanan, Synthesis, 2006, 2531-2534. A practical and environmentally friendly method for the oxidative rearrangement of five- and six-membered cyclic tertiary allylic alcohols to α,β-unsaturated β-disubstituted ketones by IBX in DMSO is described. Several conventional protecting groups (e.g., Ac, MOM, and TBDPS) are tolerated. M. Shibuya, S. Ito, M. Takahashi, Y. Continue reading >>

Reaction Of Ketones With Lithium Hexamethyldisilazide: Competitive Enolizations And 1,2-additions.

Reaction Of Ketones With Lithium Hexamethyldisilazide: Competitive Enolizations And 1,2-additions.

Abstract Reaction of 2-methylcyclohexanone with lithium hexamethyldisilazide (LiHMDS, TMS(2)NLi) displays highly solvent-dependent chemoselectivity. LiHMDS in THF/toluene effect enolization. Rate studies using in situ IR spectroscopy are consistent with a THF concentration-dependent monomer-based pathway. LiHMDS in pyrrolidine/toluene affords exclusively 1,2-addition of the pyrrolidine fragment to form an alpha-amino alkoxide-LiHMDS mixed dimer shown to be a pair of conformers by using (6)Li, (15)N, and (13)C NMR spectroscopies. Rate studies are consistent with a monomer-based transition structure [(TMS(2)NLi)(ketone)(pyrrolidine)(3)](). The partitioning between enolization and 1,2-addition is kinetically controlled. 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 >>

Aldehydes And Ketones

Aldehydes And Ketones

Can you resist the smell of a fresh baked cinnamon bun? There’s nothing like the smell of a fresh cinnamon roll. The taste is even better. But what causes that delicious taste? This flavoring comes from the bark of a tree (actually, several different kinds of trees). One of the major compounds responsible for the taste and odor of cinnamon is cinnamaldehyde. Cinnamon has been widely used throughout the centuries to treat a number of different disorders. In ancient times, doctors believed it could cure snakebite poisoning, freckles, and the common cold. Today there are several research studies being carried out on the health benefits of cinnamon. So, enjoy that cinnamon roll – it just might be good for you. Aldehydes and Ketones Aldehydes and ketones are two related categories of organic compounds that both contain the carbonyl group, shown below. The difference between aldehydes and ketones is the placement of the carbonyl group within the molecule. An aldehyde is an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon chain. A ketone is an organic compound in which the carbonyl group is attached to a carbon atom within the carbon chain. The general formulas for each are shown below. For aldehydes, the R group may be a hydrogen atom or any length carbon chain. Aldehydes are named by finding the longest continuous chain that contains the carbonyl group. Change the –e at the end of the name of the alkane to –al. For ketones, R and R’ must be carbon chains, of either the same or different lengths. The steps for naming ketones, followed by two examples, are shown below. Name the parent compound by finding the longest continuous chain that contains the carbonyl group. Change the –e at the end of the name of the alkane t Continue reading >>

Aldehydes And Ketones

Aldehydes And Ketones

Aldehydes and ketones incorporate a carbonyl functional group, C=O. These are organic compounds with structures -CHO and RC(=O)R’ where R and R’ represent carbon-containing substituents respectively. Aldehydes and Ketones are often called as methanoyl or formyl group. The carbon atom of this group has 2 remaining bonds that might be occupied by aryl or alkyl or substituents. If neither of these substituents is hydrogen, the compound is a Ketone. If at least one is hydrogen, the compound is an Aldehyde. Aldehydes In aldehydes, the carbonyl group has one hydrogen atom attached to it together with either a 2nd hydrogen atom or a hydrogen group which may be an alkyl group or one containing a benzene ring. Example: Ketones In ketones, the carbonyl group has 2 hydrocarbon groups attached to it. These can be either the ones containing benzene rings or alkyl groups. Ketone does not have a hydrogen atom attached to the carbonyl group. Example: Propane is generally written as CH3COCH3. In pentanone, the carbonyl group could be in the middle of the chain or next to the end – giving either pentan-3-one or pentan-2-one. Occurrence of Aldehydes and Ketones Combined with other functional group aldehydes and ketone are widespread in nature. Compounds such as cinnamaldehyde (cinnamon bark), vanillin (vanilla bean), Citra (lemongrass), helminthosporal (a fungal toxin), carvone (spearmint and caraway), camphor (camphor trees) are found chiefly in microorganisms or plants. Whereas, compounds such as muscone (musk deer), testosterone (male sex hormone), progesterone (female sex hormone), cortisone (adrenal hormone) have animal and human origin. Uses of Aldehydes and Ketones Formaldehyde is the simplest aldehyde whereas acetone is the smallest ketone. There are a number of aldehydes an Continue reading >>

Naming Ketones

Naming Ketones

Ketones are organic chemical compounds that include a -carbonyl group (i.e. an oxygen atom attached to a carbon atom by a double covalent bond) such that the carbon atom to which the -carbonyl group is attached is itself attached to two other carbon atoms - as opposed to one other carbon atom and one hydrogen atom, which the case for aldehydes That is, ketones are a class or category of organic chemical compounds that include a carbon atom attached to both an oxygen atom (by a double covalent bond), and also to two other carbon atoms (by a single covalent bond in each case). Bearing in mind that carbon atoms form a total of 4 single covalent bonds - or equivalent in combinations of double or triple bonds, a carbon atom attached to both an oxygen atom (by a double covalent bond) and also to two other carbon atoms (by a single covalent bond in each case) cannot be the first- or last - (which are equivalent positions) carbon atom in the chain of carbon atoms that form the organic molecule of which it is a part. This position of the -carbonyl group (oxygen atom) attached to a carbon atom that is not the last carbon atom in a carbon-chain is important because it distinguishes ketones from a similar category of organic compounds, called aldehydes. In contrast to ketones, aldehydes include a -carbonyl group attached to the end-carbon in a carbon-chain. Ketone molecules can vary in size up to very long molecules most of which consist of carbon atoms attached to each other and also to hydrogen atoms. Continue reading >>

Aldehydes And Ketones

Aldehydes And Ketones

Introduction We will focus more specifically on the organic compounds that incorporate carbonyl groups: aldehydes and ketones. Key Terms Aldehyde Formyl group Ketone Hydrogen bonding Hydration Hydrate Objectives Identify IUPAC names for simple aldehydes and ketones Describe the boiling point and solubility characteristics of aldehydes and ketones relative to those of alkanes and alcohols Characterize the process of nucleophilic addition to the carbonyl group The carbonyl group is shown below in the context of synthesizing alcohols. This functional group is the key component of aldehydes and ketones, which we will discuss here. Nomenclature for Aldehydes and Ketones Aldehydes and ketones are structurally similar; the only difference is that for an aldehyde, the carbonyl group has at most one substituent alkyl group, whereas the carbonyl group in a ketone has two. Several examples of aldehydes and ketones are depicted below. Aldehydes are named by replacing the -e ending of an alkane with -al (similarly to the use of -ol in alcohols). The base molecule is the longest carbon chain ending with the carbonyl group. Furthermore, the carbon atom in the carbonyl group is assumed to be carbon 1, so a number is not needed in the IUPAC name to identify the location of the doubly bonded oxygen atom. If the chain contains two carbonyl groups, one at each end, the correct suffix is -dial (used in the same manner as -diol for compounds with two hydroxyl groups). An example aldehyde is shown below with its IUPAC name. One- and two-carbon aldehydes have common names (one of which you will likely be familiar with) in addition to their systematic names. Both names are acceptable. Sometimes, the carbonyl group plus one proton (called a formyl group) must be treated separately for nomenclatu Continue reading >>

Difluorohomologation Of Ketones

Difluorohomologation Of Ketones

Despite significant developments in the synthesis of organofluorine compounds, efficient methods for the access of gem-difluorinated products are still limited. Indeed, the existing approaches involve either harsh deoxofluorination reagents, or multi-step functional group manipulation syntheses. α,α-Difluorinated ketones are attractive substrates for medicinal chemistry and drug discovery applications, since they efficiently form adducts (hemiketals) with water and other nucleophiles, which may resemble tetrahedral intermediates involved in the hydrolysis of peptides. Recently, a general protocol for the conversion of readily available ketones into their difluorohomologues was described by Alexander Dilman and his co-workers from Zelinsky Institute of Organic Chemistry (Moscow, Russian Federation). Read here the full article for free Difluorohomologation of Ketones Continue reading >>

Iridium-catalyzed Direct Asymmetric Reductive Amination Of Aromatic Ketones

Iridium-catalyzed Direct Asymmetric Reductive Amination Of Aromatic Ketones

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Ketones As Directing Groups In Photocatalytic Sp3 C–h Fluorination

Ketones As Directing Groups In Photocatalytic Sp3 C–h Fluorination

The ubiquitous ketone carbonyl group generally deactivates substrates toward radical-based fluorinations, especially sites closest to it. Herein, ketones are used instead to direct aliphatic fluorination using Selectfluor, catalytic benzil, and visible light. Selective β- and γ-fluorination are demonstrated on rigid mono-, di-, tri-, and tetracyclic (steroidal) substrates employing both cyclic and exocyclic aliphatic ketones as directing groups. Continue reading >>

Aldehydes And Ketones

Aldehydes And Ketones

Only methanal is a gas at RTP the rest are liquids then solids. Only those with low molecular mass are completely miscible in water, solubility in water decreases as molecular mass increases. They are all soluble in organic solvents. Nature of the carbonyl group The carbonyl group is simply a carbon atom with a double bond to an oxygen atom. The oxygen atom has two lone pairs of electrons. The double bond consists of one σ bond and one π bond. As the oxygen is highly electronegative, the electrons in both these bonds are not distributed equally, there being a strong pull towards the oxygen. This is greater in the π bond than the σ bond because the bonds are more mobile. This polarisation is often represented as: Where the π cloud is distorted, and the σ cloud is slightly distorted. The three sigma bonds attached to the carbon are in one plane, with bond angles of 120o, the π cloud sits above and below this plane. This polarisation of the C=O means that they are susceptible to attack by nucleophile on the δ+ carbon and the electrophiles on the δ- oxygen. The two lone pairs on the oxygen make it particularly susceptible to attacks by protons and Lewis acids. Reducing properties of aldehydes Aldehydes carry a hydrogen atom next to their carbonyl group. This hydrogen is activated by the carbonyl group and is readily oxidised to OH. Aldehydes are therefore readily oxidised to carboxylic acids. Ketones are not readily oxidised at all. They have no effect on mild oxidising agents. This is because they do not have an oxidisable hydrogen atom joined to the carbonyl group. a) When warmed in Fehlings solution, an alkaline solution of Cu2+ ions (a red precipitate of copper (I) oxide) is produced with an carboxylic acid. This is used to detect the aldehyde group in reducing Continue reading >>

A Simple Formula For 7 Important Aldehyde/ketone Reactions

A Simple Formula For 7 Important Aldehyde/ketone Reactions

Here’s one thing you’re going to learn about reactions of aldehydes and ketones. There’s a LOT of repetition in the mechanism. You’ll see this in more detail soon, but let’s get a taste of how things work. Imagine you’re a guitar player. And someone tells you that you need to learn how to play 14 songs… ASAP. Sounds scary, right? But what if you then found that each of these songs had the exact same sequence of chords, and only differed in their lyrics? That’s a lot easier. We’re going to go through 14 reactions in this post. BUT… before you run away screaming… it’s really just ONE reaction… that works on both aldehydes and ketones… that has seven different variants. That sounds a lot simpler, right? All of the following reactions listed here proceed through the exact same sequence: Addition of nucleophile to the carbonyl carbon. Protonation of the oxygen. The reactions are the following: Grignard reaction Addition of organolithiums Reduction of aldehydes and ketones with NaBH4 and LiAlH4 Addition of (-)CN to give cyanohydrins This works for both aldehydes and ketones (even though just aldehydes are shown here). Apologies – big image. All we’re doing here is changing the identity of the nucleophile! It’s like having a formula, and all we’re doing is plugging a different nucleophile into the formula. Do you see how knowing the mechanisms here is going to make your life much easier? Because instead of having to keep track of 14 different reactions (7 different nucleophiles with aldehydes or ketones) you’re really just learning ONE reaction, with 7 different nucleophiles and two variants (aldehydes/ketones). Thanks for reading! James Organic Chemistry 2 builds on the concepts from Org 1 and introduces a lot of new reactions. Here is an Continue reading >>

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