Mixed ketone

If a mixture of monobasic acids is employed, the mixed ketone may be pre- ... 

Note also the stereochemistry. In some cases, two new stereogenic centers are formed. The hydroxyl group and any C(2) substituent on the enolate can be in a syn or anti relationship. For many aldol addition reactions, the stereochemical outcome of the reaction can be predicted and analyzed on the basis of the detailed mechanism of the reaction. Entry 1 is a mixed ketone-aldehyde aldol addition carried out by kinetic formation of the less-substituted ketone enolate. Entries 2 to 4 are similar reactions but with more highly substituted reactants. Entries 5 and 6 involve boron enolates, which are discussed in Section 2.1.2.2. Entry 7 shows the formation of a boron enolate of an amide reactions of this type are considered in Section 2.1.3. Entries 8 to 10 show titanium, tin, and zirconium enolates and are discussed in Section 2.1.2.3. 

Extension of this condensation to mixed ketones (95) provided further confirmation for the above interpretation. Thus, methyl ethyl ketone and p-chlorophenylbiguanide gave successively the triazine derivatives (CXXVIII) and (CXXIX). The latter (CXXIX) was resolvable into its enantiomers by (+)-tartaric acid this observation supports the six-membered ring structure of (CXXIX) and, because of the very gentle conditions of its isomerisation, that of its isomer (CXXVIII). 

In the case of the benzothiazole system, both aldehydes and mixed ketones have been synthesized by reduction or alkylation of the appropriate carbonyl precursors. The carbonyl compounds are in turn prepared from the benzothiazole-2-anion either directly by reaction with esters or indirectly by reaction with aldehydes followed by PCC oxidation (Scheme 154) (85H2467 91BCJ3256). 

When H is replaced by R no isomerism occurs but if it is replaced by Ri, as in the case of mixed ketones, two isomeric forms exist ... 

This ketone synthesis was developed further by Ipatieff and by Sabatier, Mailhe, and Senderens. Thoria and manganous oxide proved to be more effective catalysts than the carbonates. The method was extended to higher fatty acids and to the production of mixed ketones. 

If the chloracetic acid above is replaced by an aliphatic or mixed ketone, such as bromacetophenone, a ketonic group is introduced as in I, and the compounds are known as ketobetaines ... 

These are general methods for the formation of ketones and aldehydes. By the first action, if the salt of only one acid is used, the ketone will always be a simple ketone and will contain the same alkyl radicals as the acid. In case a mixture of acids other than formic acid is used the product will be partly a mixed ketone containing the two alkyl radicals of the acids used. The second reaction always yields the aldehyde corresponding to the acid other than formic. 

The compound so formed is a mixed ketone acid and as such will be referred to again. 

Isatin Chloride.— Now isatin which is a di-ketone of di-hydro indole, or the tautomeric form, a mixed ketone and hydroxyl derivative of indole, yields a chloride when treated with phosphorus pentachloride. 

Similarly the formation of simple and mixed ketones and of aldehydes ... 

In this section, we discuss a useful version of mixed ketone-aldehyde condensation, the reaction of aromatic methyl ketones with nonenolizable (usually aromatic) aldehydes. The prototype reaction is the condensation of acetophenone with benzaldehyde, leading to l,3-diphenylprop-2-en-l-one, chalcone (equation 81). The scope of this reaction is exceedingly broad the Nielsen-Houlihan review enumerates hundreds of examples comprising almost every imaginable combination of substituted acetophenone and aromatic aldehyde. - ... 

For a mixture of two carboxylic acids, two self-ketonization and one mixed ketonization are possible. 

A pressure of 70 atmospheres of CO is required since hindered boranes, especially thexylborane, react sluggishly at atmospheric pressure. However, thexylborane reacted with cyclopentene to generate 188, and subsequent reaction with O-acetyl-hept-6-en-l-ol gave the trialkylborane (189). Carbonylation in the presence of water followed by oxidation gave the mixed ketone (190) in 73% yield. 33 In a similar manner, dienes can be transformed into the corresponding cyclic ketones. 34,135... 

These derivatives under the influence of sodium hydroxide or carbonate are transformed to the free betaines, Type II. Similar compounds may also be obtained by the oxidation by alkaline potassium permanganate of aryltrialkylphosphonium chlorides (in which the aryl group contains a substituted methyl group). If the chloracetic acid in the foregoing condensation be replaced by an aliphatic or mixed ketone, a ketonic group is introduced as in I, and the derivatives are known as ketobetaines ... 

August Sayer (U.S.P., No. 470,451) finds diethyl-ketone, dibutyl-ketone, di-pentyl-ketone, and the mixed ketones, [A] methyl-ethyl, methyl-propyl, methyl-butyl, methyl-amyl, and ethyl-butyl ketones are active solvents of pyroxyline and Paget finds that although methyl-amyl oxide is a solvent, that ethyl-amyl oxide is not. 

Footnote A Ketones are derived from the fatty acids by the substitution of the hydroxyl of the latter by a monad positive radical. They thus resemble aldehydes in constitution. The best-known ketone is acetone CH 3 CO.CH 3. Mixed ketones are obtained by distilling together salts of two different fatty acids. Thus potassic butyrate and potassic acetate form propyl-methyl-ketone-... 

Mr W.D. Field groups the solvents of pyroxyline into classes thus Two of the monohydric alcohols compound ethers of the fatty acids with monohydric alcohols, aldehydes simple and mixed ketones of the fatty acid series. These four classes inelude the greater number of the solvents of pyroxyline. Those not included are as follows —Amyl-nitrate and nitrite, methylene-di-methyl ether, ethidene-diethyl ether, amyl-chloracetate, nitro-benzene and di-nitro-benzene, eoumarin, eamphor, glacial acetic acid, and mono-, di-, and tri-acetin. 

Cellulose nitrates with DS values of 1.8-2.3 are used in plastics, lacquers, coatings, and adhesives. The most common use as an adhesive is as general-purpose household cement, in which the nitrate and a plasticizer are dissolved in a mixed ketone-ester organic solvent. Upon application to the substrate, the solution rapidly loses solvent to form tough, moisture-resistant, clear films. These thermoplastic films are prone to discoloration upon exposure to sunlight, and, as might be expected, are very flammable. 

The results obtained by carrying out the usual Grignard reaction are different than that obtained in the solid state. Thus the reaction of ketone (e.g. benzophenone) with Grignard reagent (the reaction carried out by mixing ketone... 

The claim that site-separation is achieved in the reactions discussed earlier has been questioned (Crowley and Rapoport, 1976 Neckers, 1978). According to these authors, the Claissen condensation of two molecules of an ester resulting in self-condensation cannot be expected to compete with acylation using acid chlorides or acid anhydrides (more powerful acylating agents). Hence, the formation of mixed ketones as the major product cannot be attributed mainly to site-separation. Furthermore, if site-separation did take place by polymer binding, then why were self-condensation products formed in other reactions The evidence for effective site-separation is contradictory because self-condensation has taken place in some cases and not in others. This difference is better explained in terms of a competitive reaction that takes place in one case and not in the other. 

There are two main synthesis routes in commerce to produce MIBK. One starts with acetone and involves intermediates of diacetone alcohol and mesityl oxide. The second synthesis route uses 2-propanol, involving a mixed ketone process with coproducts including diisobutyl ketone (DIBK) and acetone. 

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