diabetestalk.net

Ketone Group

Protecting Groups In Grignard Reactions

Protecting Groups In Grignard Reactions

Now that we’ve gone over the most useful reactions of Grignard reagents – addition to epoxides, aldehydes, ketones, and esters – let’s go back to the topic of how to make Grignard reagents, albeit with a twist. Here’s the summary for today’s post: Introducing Yet Another Way To Royally Screw Up Making A Grignard Reagent In a previous post we said that there are cases where making Grignard reagents can fail due to the presence of an acidic proton. Like this example. The problem here is that Grignard reagents are strong bases, and will react with even weak acids (like alcohols). If we try to make a Grignard on a molecule with an acidic functional group, we’ll end up destroying our Grignard instead. We saw that one way around this problem was to protect alcohols as some kind of inert functional group (like an ether) which doesn’t react with our Grignard. Similarly, there are other cases of molecules where making a Grignard reagent will fail for similar reasons. For example: why does this reaction not give the desired Grignard reagent? The problem here, as you might have guessed if you read the last post, is that this Grignard reagent reacts with itself!!! Once formed, the Grignard would react with the ketone from the starting material. This could then react with Mg to give a new Grignard, which would react with more ketone… and so on. The result is a mess. “Protecting Groups” Mask A Functional Group From Attack If we were able to find some way to “mask” the ketone in this case, possibly as some unreactive functional group that is completely inert to Grignard reagents, then we could then make the Grignard reagent without causing any problems of self-reactivity. Then, once we’re done, we could then “unmask” the protecting or masking group, rev Continue reading >>

14.9: Aldehydes And Ketones: Structure And Names

14.9: Aldehydes And Ketones: Structure And Names

Identify the general structure for an aldehyde and a ketone. Use common names to name aldehydes and ketones. Use the IUPAC system to name aldehydes and ketones. The next functional group we consider, the carbonyl group, has a carbon-to-oxygen double bond. Carbonyl groups define two related families of organic compounds: the aldehydes and the ketones. The carbonyl group is ubiquitous in biological compounds. It is found in carbohydrates, fats, proteins, nucleic acids, hormones, and vitamins—organic compounds critical to living systems. In a ketone, two carbon groups are attached to the carbonyl carbon atom. The following general formulas, in which R represents an alkyl group and Ar stands for an aryl group, represent ketones. In an aldehyde, at least one of the attached groups must be a hydrogen atom. The following compounds are aldehydes: In condensed formulas, we use CHO to identify an aldehyde rather than COH, which might be confused with an alcohol. This follows the general rule that in condensed structural formulas H comes after the atom it is attached to (usually C, N, or O). The carbon-to-oxygen double bond is not shown but understood to be present. Because they contain the same functional group, aldehydes and ketones share many common properties, but they still differ enough to warrant their classification into two families. Here are some simple IUPAC rules for naming aldehydes and ketones: The stem names of aldehydes and ketones are derived from those of the parent alkanes, defined by the longest continuous chain (LCC) of carbon atoms that contains the functional group. For an aldehyde, drop the -e from the alkane name and add the ending -al. Methanal is the IUPAC name for formaldehyde, and ethanal is the name for acetaldehyde. For a ketone, drop the -e from t 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 >>

An Inert Hydrocarbon Skeleton Onto Which Functional Groups (fgs) Are Attached Or Superimposed.

An Inert Hydrocarbon Skeleton Onto Which Functional Groups (fgs) Are Attached Or Superimposed.

Organic Functional Groups: Aldehydes, ketones, primary alcohols, etc. (Indonesian Translation of this page) Organic chemistry is dominated by the "functional group approach", where organic molecules are deemed to be constructed from: The functional group approach "works" because the properties and reaction chemistry of a particular functional group (FG) can be remarkably independent of environment. Therefore, it is only necessary to know about the chemistry of a few generic functions in order to predict the chemical behaviour of thousands of real organic chemicals. Organic molecules are also named using the functional group approach: 2-hexanone 2-hexanol 2-chlorohexane The rule is that functions assume their distinct identity when separated by –CH2– groups. Thus, the carbonyl, C=O, and hydroxy, OH, of a carboxylic acid, RCOOH, are part of a single function and are NOT "alcohol-plus-ketone": A Couple of Words About The Functional Group Approach The functional group approach is 100% empirical in that it is determined by experiment and experience, and not by theory (unlike VSEPR, for example.) A multifunctional entity like the drug molecule morphine has several functional groups and chiral centres: Professional chemists consider large multifunctional organic molecules in terms of 'substructures' rather than functional groups. Ring systems, for example, are better considered as substructures, although the dividing line can be fuzzy... What You Need To Know To be proficient in organic chemistry at university entrance level [ie, American AP, British A-Level or French Baccalaureate] exam systems, in other words be able to: name organic molecules predict solubility in different types of solvent predict chemical reactivity predict spectra it is absolutely essential to be abl Continue reading >>

Aldehydes And Ketones

Aldehydes And Ketones

Carbonyl goup: the oxygen atom is electronegative Aldehydes and Ketones are molecules of carbon, oxygen and hydrogen that have, as part of their structure a reactive group called a carbonyl group, typically written C=O. The carbon atom in a carbonyl group can still form two additional covalent bonds. If this carbon atoms is joined with two other carbon atoms then the compound formed is a ketone, but if this carbon is joined with a hydrogen, then the compound is an aldehyde. The oxygen atom in the carbonyl group pulls the shared electrons towards it, causing an imbalance in the distribution of positive and negative charges. (The oxygen is said to be more electronegative). This polarity of charge has two effects on the physical properties of molecules containing this reactive group; aldehydes and ketones have higher boiling points, and they are more water soluble than similar hydrocarbons. The unequal charges on the oxygen atom and the carbon atom of the carbonyl group also affects the kind and type of chemical reactions that these molecules undergo. For example, water will interact with the carbonyl group very, very rapidly forming a short lived intermediate with two -OH (hydroxyl groups) which then very rapidly breaks up into water and a carbonyl group once more. The rapid addition of water (H-OH) to the carbonyl group produces a hydrate which is very unstable and cannot be isolated as a separate molecule or compound. However, if, instead of water, an alcohol (R-OH) is used a similar kind of chemical reaction takes place in which a hemiacetal is formed. Most of these hemiacetals are not stable and quickly break down once more, however, there is at least one example where a molecule with five carbon atoms in a chain with an -OH group at one end, and an aldehyde group (-H Continue reading >>

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

Ketone

The Columbia Encyclopedia, 6th ed. Copyright The Columbia University Press ketone (kē´tōn), any of a class of organic compounds that contain the carbonyl group, C[symbol]O, and in which the carbonyl group is bonded only to carbon atoms. The general formula for a ketone is RCOR′, where R and R′ are alkyl or aryl groups. The simplest ketone, where R and R′ are methyl groups, is acetone; this is one of the most important ketones used in industry. Low-molecular-weight ketones are used chiefly as solvents. Ketones may be prepared by several methods, including the oxidation of secondary alcohols and the destructive distillation of certain salts of organic acids. Ketones are related to the aldehydes but are less active chemically. 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 >>

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 >>

Functional Group Names, Properties, And Reactions

Functional Group Names, Properties, And Reactions

Functional Groups Functional groups refer to specific atoms bonded in a certain arrangement that give a compound certain physical and chemical properties. Learning Objectives Define the term “functional group” as it applies to organic molecules Key Takeaways Functional groups are often used to “functionalize” a compound, affording it different physical and chemical properties than it would have in its original form. Functional groups will undergo the same type of reactions regardless of the compound of which they are a part; however, the presence of certain functional groups within close proximity can limit reactivity. Functional groups can be used to distinguish similar compounds from each other. functional group: A specific grouping of elements that is characteristic of a class of compounds, and determines some properties and reactions of that class. functionalization: Addition of specific functional groups to afford the compound new, desirable properties. The Role of Functional Groups In organic chemistry, a functional group is a specific group of atoms or bonds within a compound that is responsible for the characteristic chemical reactions of that compound. The same functional group will behave in a similar fashion, by undergoing similar reactions, regardless of the compound of which it is a part. Functional groups also play an important part in organic compound nomenclature; combining the names of the functional groups with the names of the parent alkanes provides a way to distinguish compounds. The atoms of a functional group are linked together and to the rest of the compound by covalent bonds. The first carbon atom that attaches to the functional group is referred to as the alpha carbon; the second, the beta carbon; the third, the gamma carbon, etc. Simi Continue reading >>

Introducing Aldehydes And Ketones

Introducing Aldehydes And Ketones

This page explains what aldehydes and ketones are, and looks at the way their bonding affects their reactivity. It also considers their simple physical properties such as solubility and boiling points. Details of the chemical reactions of aldehydes and ketones are described on separate pages. What are aldehydes and ketones? Aldehydes and ketones as carbonyl compounds Aldehydes and ketones are simple compounds which contain a carbonyl group - a carbon-oxygen double bond. They are simple in the sense that they don't have other reactive groups like -OH or -Cl attached directly to the carbon atom in the carbonyl group - as you might find, for example, in carboxylic acids containing -COOH. Examples of aldehydes In aldehydes, the carbonyl group has a hydrogen atom attached to it together with either a second hydrogen atom or, more commonly, a hydrocarbon group which might be an alkyl group or one containing a benzene ring. For the purposes of this section, we shall ignore those containing benzene rings. Note: There is no very significant reason for this. It is just that if you are fairly new to organic chemistry you might not have come across any compounds with benzene rings in them yet. I'm just trying to avoid adding to your confusion! Notice that these all have exactly the same end to the molecule. All that differs is the complexity of the other group attached. When you are writing formulae for these, the aldehyde group (the carbonyl group with the hydrogen atom attached) is always written as -CHO - never as COH. That could easily be confused with an alcohol. Ethanal, for example, is written as CH3CHO; methanal as HCHO. The name counts the total number of carbon atoms in the longest chain - including the one in the carbonyl group. If you have side groups attached to the ch 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 >>

Monosaccharides Are Aldehydes Or Ketones With Multiple Hydroxyl Groups

Monosaccharides Are Aldehydes Or Ketones With Multiple Hydroxyl Groups

Monosaccharides, the simplest carbohydrates, are aldehydes or ketones that have two or more hydroxyl groups; the empirical formula of many is (C-H2O)n, literally a “carbon hydrate.” Monosaccharides are important fuel molecules as well as building blocks for nucleic acids. The smallest monosaccharides, for which n = 3, are dihydroxyacetone and d- and l-glyceraldehyde. They are referred to as trioses (tri- for 3). Dihydroxyacetone is called a ketose because it contains a keto group, whereas glyceraldehyde is called an aldose because it contains an aldehyde group. Glyceraldehyde has a single asymmetric carbon and, thus, there are two stereoisomers of this sugar. d-Glyceraldehyde and l-glyceraldehyde are enantiomers, or mirror images of each other. As mentioned in Chapter 3, the prefixes d and l designate the absolute configuration. Monosaccharides and other sugars will often be represented in this book by Fischer projections (Figure 11.1). Recall that, in a Fischer projection of a molecule, atoms joined to an asymmetric carbon atom by horizontal bonds are in front of the plane of the page, and those joined by vertical bonds are behind (see the Appendix in Chapter 1). Fischer projections are useful for depicting carbohydrate structures because they provide clear and simple views of the stereochemistry at each carbon center. Simple monosaccharides with four, five, six, and seven carbon atoms are called tetroses, pentoses, hexoses, and heptoses, respectively. Because these molecules have multiple asymmetric carbons, they exist as diastereoisomers, isomers that are not mirror images of each other, as well as enantiomers. In regard to these monosaccharides, the symbols d and l designate the absolute configuration of the asymmetric carbon farthest from the aldehyde or keto g Continue reading >>

What Is Ketone? - Definition, Structure, Formation & Formula

What Is Ketone? - Definition, Structure, Formation & Formula

Background of Ketone Did you know that our friend aldehyde has a very close relative named ketone? By definition, a ketone is an organic compound that contains a carbonyl functional group. So you may be wondering if aldehydes and ketones are relatives, what makes them different? Well, I am glad you asked because all you have to remember is this little guy: hydrogen. While aldehyde contains a hydrogen atom connected to its carbonyl group, ketone does not have a hydrogen atom attached. There are a few ways to know you are encountering a ketone. The first is by looking at the ending of the chemical word. If the suffix ending of the chemical name is '-one,' then you can be sure there is a ketone present in that compound. Want to know another way to tell if a ketone is lurking around the corner? By its physical property. Ketones have high boiling points and love water (high water solubility). Let's dig a little deeper with the physical property of a ketone. The oxygen in a ketone absolutely loves to take all the electrons it can get its hands on. But, by being an electron-hogger, oxygen's refusal to share creates a sticky situation where some atoms on the ketone have more or less charge than others. In chemistry, an electron-hogging atom is referred to as being electronegative. An electronegative atom is more attractive to other compounds. This attractiveness, called polarity, is what contributes to ketones' physical properties. Structure & Formula Ketones have a very distinct look to them; you can't miss it if you see them. As shown in Diagram 1, there are two R groups attached to the carbonyl group (C=O). Those R groups can be any type of compound that contains a carbon molecule. An example of how the R group determines ketone type is illustrated in this diagram here. The 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 >>

More in ketosis