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Is Ketone An Acid Or Base

Base-catalysed Bromination Of Ketones

Base-catalysed Bromination Of Ketones

Click each of the reaction schemes below to view the 3D models and animations respectively The hydroxide removes a proton from the ketone to form an enolate anion. The enolate anion attacks the bromine molecule yielding a mono-substituted bromoketone. The reaction continues until the tribromoketone is formed. The hydroxide then attacks directly at the carbonyl and a tribromomethyl anion is lost. E. Tapuhi and W. P. Jencks, J. Am. Chem. Soc., 1982, 104, 5758–5765. Continue reading >>

Reactive Group Datasheet

Reactive Group Datasheet

Many low-molecular-weight ketones (such as acetone and methyl ethyl ketone) are highly flammable. Most ketones are liquids with relatively high vapor pressures, capable of forming explosive mixtures with air. Materials in this group are reactive with many acids and bases liberating heat and flammable gases (e.g., H2 from NaH). The amount of heat may be sufficient to start a fire in the unreacted portion of the ketone. Ketones react with reducing agents such as hydrides, alkali metals, and nitrides to produce flammable gas (H2) and heat. Ketones are incompatible with isocyanates, aldehydes, cyanides, peroxides, and anhydrides. They react violently with HNO3, HNO3 + H2O2, and HClO4. Varies very widely. Some ketones are highly volatile and may have narcotic or anesthetic effects. Entry into the body occurs by absorption through the skin as well as inhalation and ingestion. Compounds in this group are characterized by a carbonyl attached to two organic groups. These groups may be alkyl (paraffins) or aryl (aromatic). Reactions of this group are very similar in their behavior to that of aldehydes, because of their similar structure. These materials are generally used as solvents in the paint, textiles, plastics, and lacquer industries. 2-tridecanone, acetone, acetophenone, benzoin, cyclohexanone, isophorone, methyl acetone, methyl amyl ketone, methyl butanone, methyl ethyl ketone, ninhydrin. 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 >>

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 >>

Reactions Of Aldehydes And Ketones

Reactions Of Aldehydes And Ketones

Aldehydes and ketones undergo a variety of reactions that lead to many different products. The most common reactions are nucleophilic addition reactions, which lead to the formation of alcohols, alkenes, diols, cyanohydrins (RCH(OH)C&tbond;N), and imines R 2C&dbond;NR), to mention a few representative examples. The main reactions of the carbonyl group are nucleophilic additions to the carbon‐oxygen double bond. As shown below, this addition consists of adding a nucleophile and a hydrogen across the carbon‐oxygen double bond. Due to differences in electronegativities, the carbonyl group is polarized. The carbon atom has a partial positive charge, and the oxygen atom has a partially negative charge. Aldehydes are usually more reactive toward nucleophilic substitutions than ketones because of both steric and electronic effects. In aldehydes, the relatively small hydrogen atom is attached to one side of the carbonyl group, while a larger R group is affixed to the other side. In ketones, however, R groups are attached to both sides of the carbonyl group. Thus, steric hindrance is less in aldehydes than in ketones. Electronically, aldehydes have only one R group to supply electrons toward the partially positive carbonyl carbon, while ketones have two electron‐supplying groups attached to the carbonyl carbon. The greater amount of electrons being supplied to the carbonyl carbon, the less the partial positive charge on this atom and the weaker it will become as a nucleus. The addition of water to an aldehyde results in the formation of a hydrate. The formation of a hydrate proceeds via a nucleophilic addition mechanism. 1. Water, acting as a nucleophile, is attracted to the partially positive carbon of the carbonyl group, generating an oxonium ion. Acetal formation reacti Continue reading >>

Aldol Condensation – Acid Catalyzed

Aldol Condensation – Acid Catalyzed

Aldol condensation reaction can be either acid catalyzed or base catalyzed. This page deals with the acid catalysis mechanism of the aldol reaction. Earlier, this reaction was thought to occur only with aldehydes. However, it has been realized that a similar reaction would occur with ketones and reactive carbonyl compounds with available α-hydrogens (the need for which will be apparent with the mechanism below). The reaction proceeds with the condensation of an aldehyde (or carbonyl compound) with an enol. The product formed has an aldehyde (or carbonyl) group and a β-hydroxy (alcohol) group, giving the product the name aldol (or if the carbonyl compound is a ketone it maybe called a ketol). This condensation is often followed by spontaneous dehydration due to β-elimination to produce an α,β-unsaturated aldehyde or α,β-unsaturated ketone. The mechanisms for acid catalyzed aldol condensation and base catalyzed aldol condensation is significantly different. While bases activate the nucleophile, acids activate the electrophile in the reaction. It must be noted that aldol condensation is an integral mechanism of Robinson annulation as well. Mechanism of Acid Catalyzed Aldol Condensation Step 1 In step 1 of the reaction, the acid acts as a proton donor and activates the carbonyl oxygen into a protonated form. Step 2 In step 2, the intermediate 1 reacts with the conjugate base of the acid (i.e. A-) to produce the enol (intermediate 2). Step 3 This step involves the conjugation of the enol (intermediate 2) with another molecule of the activated carbonyl compound (intermediate 1) to produce the aldol (or ketol). Step 4 In step 4, the aldol (or ketol) undergoes spontaneous dehydration due to base catalyzed dehydration to yield the α,β-unsaturated aldehyde or α,β-unsat Continue reading >>

Introduction To The Reactions Of Enols And Enolates

Introduction To The Reactions Of Enols And Enolates

Racemization of Carbonyl Compounds If aldehydes or ketones with an α hydrogen atom are chiral because of an asymmetric α carbon, racemization occurs relatively rapidly when these are treated with an acid or base. Why is this? Aldehydes and ketones with an α hydrogen atom are in equilibrium with their corresponding enols or enolates due to keto-enol tautomerism. The α carbon in enols and enolates is sp2-hybridized. Thus, its substituents are arranged trigonal planar. As a result, the stereochemical information of the sp3-hybridized carbonyl compound's α carbon is lost. Therefore, reconversion of the enol to the carbonyl compound does not proceed stereoselectively. Thus, racemization occurs. It must be kept in mind that racemization in the α position of carbonyl compounds (and other CH-acidic compounds) is possible when an enantioselective synthesis is constructed. α-Halogenation of CH-acidic Compounds If enolizable carbonyl compounds are treated with iodine, bromine, or chlorine, halogenation of the α carbon occurs. Halogenation yields different products depending on whether the reaction conditions are acidic or basic. Acid-catalyzed α-halogenation Acid-catalyzed α-halogenation leads to the exchange of only one α hydrogen for a halogen even if the α carbon carries additional hydrogens. In the initial reaction step, the enol nucleophilically attacks the halogen molecule. As a result, the halogen molecule is heterolytically cleaved and a single bond between the α carbon and a halogen atom is formed. That is, the reaction step yields a halide anion, as well as a protonated and, thus, positively charged α-halocarbonyl compound. Deprotonation results in the formation of the α-halocarbonyl compound. Under acidic conditions, the enol is continually supplied throu Continue reading >>

Home Page

Home Page

Explanation on the observed regioselective and stereoselective outcome of the Luche reduction of 19 While the Luche reduction has been tested for over 30 years, a clear explanation for the stereoselective outcomes of compounds which undergo this sort of reduction is still vague and unknown. The novel characteristic of the Luche reduction is its ability to not affect specific groups such as carboxylic acids, esters, amides, halides, and cyano and nitro groups. When looking at compound 19 from the previous reaction, it may be noted that the only “available” site for reduction via the Luche method is the ketone found on the 6-membered, oxygen containing ring. Why is only this ketone (and only ketones in general) affected? While many explanations have been brought forth, the simple concept of the Hard-Soft Acid and Bases (HSAB) theory has been the most supported explanation. While hard acids or bases are compact, with the electrons held fairly tightly by the nucleus, and not very polarizable; soft acids and bases are larger, with a more diffuse distribution of electrons. Knowing this, the HSAB simply states that hard acids react preferentially with hard bases, and soft acids react preferentially with soft bases. In the case of a Luche reduction reaction, the lanthanide (Ce3+ in this case) acts to increase the electrophilicity of the specific ketone-carbonyl group. This CeCl3-O complex allows for the hardness of the borohydride (NaBH4) to increase by replacing hydride groups with alkoxide groups. Because of this increase in “hardness” the NaBH4 can now be considered a “hard” acid. Along with this, ketones have been categorized as a “hard” Lewis base. Following the HSAB theory, when the unstable CeCl3 activates the ketone, the C=O becomes delocalized (shown be Continue reading >>

Carbonyls: 10 Key Concepts (part 2)

Carbonyls: 10 Key Concepts (part 2)

If you’re on the typical college cycle, chances are you’re taking Org II right now. As you are by now well aware [more aware than you wish you were, I can hear some of you say] one of the main focii of Org II is on the many different facets of carbonyl chemistry. Following on the heels of the previous post, here are five further important points to keep in mind when studying the chemistry of these species. [Note – these will be included in the second carbonyl summary sheet, currently in preparation]. Without further ado… 6. Carbonyls make adjacent alkyl groups more acidic. How much more acidic? Consider ethane. For all practical purposes, ethane is inert to base: the pKa of its hydrogens is 50. But when you exchange one of the protons of ethane for a carbonyl group (say, -COOCH3) something phenomenal happens. The acidity changes by a factor of 10 ^25. That is an incredible number to wrap your head around. The difference in chemical reactivity between different species can be incredibly, mind-bogglingly vast. We are not talking about the difference in quarterbacking ability between Peyton Manning and Dan Marino here, or even the comparative basketball skill set of LeBron James and Verne Troyer. The differences in reactivity* are truly cosmic: like comparing the width of your armspan to the length of the Milky Way galaxy. What’s going on here? Simply put, the carbonyl π system provides a “sink” for the carbanion to donate electron density, setting up a sharing of negative charge between the α-carbon and the carbonyl oxygen. The key structural feature is not so much the resonance, although that is a factor – [the lower pKa of propene (42) is a good example of resonance stabilization] The reason why the carbonyl stabilizes the carbanion so much is that the Continue reading >>

Is A Ketone An Acid Or A Base?

Is A Ketone An Acid Or A Base?

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

22.3 Alpha Halogenation Of Aldehydes And Ketones

22.3 Alpha Halogenation Of Aldehydes And Ketones

Objectives After completing this section, you should be able to write an equation to illustrate the alpha halogenation of aldehydes and ketones. identify the product formed from the alpha halogenation of a given aldehyde or ketone. identify the carbonyl compound, the reagents, or both, needed to prepare a given α‑halogenated aldehyde or ketone. illustrate the importance of the alpha halogenation of carbonyl compounds as an intermediate step in the synthesis of α,β‑unsaturated aldehydes and ketones. write a detailed mechanism for the acid‑catalyzed halogenation of a ketone. describe the evidence provided by kinetic experiments supporting the suggestion that the acid‑catalyzed, alpha halogenation of ketones proceeds via the rate‑determining formation of an enol. Study Notes Note: α‑bromo ketones are a good starting material to generate α,β‑unsaturated ketones by dehydrobromination. A carbonyl containing compound with α hydrogens can undergo a substitution reaction with halogens. This reaction comes about because of the tendency of carbonyl compounds to form enolates in basic condition and enols in acidic condition. In these cases even weak bases, such as the hydroxide anion, is sufficient enough to cause the reaction to occur because it is not necessary for a complete conversion to the enolate. For this reaction Cl2, Br2 or I2 can be used as the halogens. General reaction Under acidic conditions the reaction occurs thought the formation of an enol which then reacts with the halogen. 1) Protonation of the carbonyl 2) Enol formation 3) SN2 attack 4) Deprotonation Kinetic studies provide some evidence for the mechanism shown above. The rate law for the alpha-halogenation of a ketone can be given by: rate = [ketone][H+] The implication is that the rate de Continue reading >>

Acidity Of

Acidity Of

a-Hydrogens In the following table, the acidity of the H for various enolate systems and other closely related systems are given. You should be able to justify the trends in this data ! Why are the protons adjacent to carbonyl groups acidic ? As we have advocated before, look at the stabilisation of the conjugate base. Notice the proximity of the adjacent p system, and hence the possibility for RESONANCE stabilisation by delocalisation of the negative charge to the more electronegative oxygen atom. The more effective the resonance stabilisation of the negative charge, the more stable the conjugate base is and therefore the more acidic the parent system. Let's compare pKa of the common systems: aldehyde pKa = 17, ketone pKa = 19 and an ester pKa = 25, and try to justify the trend. The difference between the 3 systems is in the nature of the group attached to the common carbonyl. The aldehyde has a hydrogen, the ketone an alkyl- group and the ester an alkoxy- group. H atoms are regarded as having no electronic effect : they don't withdraw or donate electrons. Alkyl groups are weakly electron donating, they tend to destabilise anions (you should recall that they stabilise carbocations). This is because they will be "pushing" electrons towards a negative system which is unfavourable electrostatically. Hence, the anion of a ketone, where there are extra alkyl groups is less stable than that of an aldehyde, and so, a ketone is less acidic. In the ester, there is also a resonance donation from the alkoxy group towards the carbonyl that competes with the stabilisation of the enolate charge. This makes the ester enolate less stable than those of aldehydes and ketones so esters are even less acidic. The most important reactions of ester enolates are the Claisen and Dieckmann cond 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 >>

Urine Test Types: Ph, Ketones, Proteins, And Cells

Urine Test Types: Ph, Ketones, Proteins, And Cells

Urine as a Diagnostic Tool A long time ago, disgusting as it may be, people used to actually taste and drink urine in order to try and diagnose a patient's disease! I'm not even kidding you. Thankfully, modern-day doctors do not have to resort to such disgusting and even dangerous methods. One of the reasons the doctor barbers of yesteryear used to drink their patient's urine was to see if it had a sweet taste, often indicative of diabetes mellitus. Finding the sweet-tasting glucose in the urine was covered in detail in another lesson, so we'll focus on other important measurements here instead. Interpreting Urine pH One value that can be measured in the urine is known as urine pH. pH is a measure of the acidity or alkalinity of a substance. If the pH is low, then it is acidic. If the pH is high, then it is basic, or alkaline. To remember which is which, I'll give you a little trick that has worked for me. If you grew up watching cartoons, you probably saw some comical ones where cartoonish robbers poured acid on the roof of a bank vault and waited while the acid ate its way downward into the vault, so the robbers could get down there to steal all the cash. If you can recall that acid likes to eat its way downward into things, then you'll remember that acidic substances go down the pH scale. That is to say, their pH numbers are lower than basic substances. Normal urine pH is roughly 4.6-8, with an average of 6. Urine pH can increase, meaning it will become more basic, or alkaline, due to: A urinary tract infection Kidney failure The administration of certain drugs such as sodium bicarbonate Vegetarian diets On the flip side, causes for a decreased, or acidic, urine pH, include: Metabolic or respiratory acidosis Diabetic ketoacidosis, a complication of diabetes mellitus Continue reading >>

Ketoacidosis Versus Ketosis

Ketoacidosis Versus Ketosis

Some medical professionals confuse ketoacidosis, an extremely abnormal form of ketosis, with the normal benign ketosis associated with ketogenic diets and fasting states in the body. They will then tell you that ketosis is dangerous. Testing Laboratory Microbiology - Air Quality - Mold Asbestos - Environmental - Lead emsl.com Ketosis is NOT Ketoacidosis The difference between the two conditions is a matter of volume and flow rate*: Benign nutritional ketosis is a controlled, insulin regulated process which results in a mild release of fatty acids and ketone body production in response to either a fast from food, or a reduction in carbohydrate intake. Ketoacidosis is driven by a lack of insulin in the body. Without insulin, blood sugar rises to high levels and stored fat streams from fat cells. This excess amount of fat metabolism results in the production of abnormal quantities of ketones. The combination of high blood sugar and high ketone levels can upset the normal acid/base balance in the blood and become dangerous. In order to reach a state of ketoacidosis, insulin levels must be so low that the regulation of blood sugar and fatty acid flow is impaired. *See this reference paper. Here's a table of the actual numbers to show the differences in magnitude: Body Condition Quantity of Ketones Being Produced After a meal: 0.1 mmol/L Overnight Fast: 0.3 mmol/L Ketogenic Diet (Nutritional ketosis): 1-8 mmol/L >20 Days Fasting: 10 mmol/L Uncontrolled Diabetes (Ketoacidosis): >20 mmol/L Here's a more detailed explanation: Fact 1: Every human body maintains the blood and cellular fluids within a very narrow range between being too acidic (low pH) and too basic (high pH). If the blood pH gets out of the normal range, either too low or too high, big problems happen. Fact 2: The Continue reading >>

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