1 Classification reactions Ketones

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

When unknown compounds are identified without the aid of spectroscopy classification tests are used. Reacting the carbonyl in a ketone or aldehyde with an amine (2,4 dinitro-phenylhydrazine) to form an inline is the easiest way to detect a ketone or aldehyde (Reaction l). The iinine that forms is a highly colored solid. The color of the solid also helps to indicate structural characteristics. Ketones and aldehydes with no conjugation tend to form itnines with yellow to orange colors, while highly conjugated ketones or aldehydes form imines with red color. 

The presence of a colored solid confirms the presence of a ketone or aldehyde, but the imine formation does not indicate whether the unknown is a ketone or aldehyde. A second classification test is used to distinguish the two functionalities. This test is called the Tpllens test, and die significant reaction is shown in Reaction 2. 

The classification tests (summarized in Table 31.2), when properly done, can distinguish between various types of aldehydes and ketones. However, these tests alone may not allow for the identification of a specific unknown aldehyde or ketone. A way to correctly identify an unknown compound is by using a known chemical reaction to convert it into another compound that is known. The new compound is referred to as a derivative. Then, by comparing the physical properties of the unknown and the derivative to the physical properties of known compounds listed in a table, an identification can be made. 

Classification and Organization of Reactions Forming Difunctional Compounds. This chapter considers all possible difunctional compounds formed from the groups acetylene, carboxylic acid, alcohol, thiol, aldehyde, amide, amine, ester, ether, epoxide, thioether, halide, ketone, nitrile, and olefin. Reactions that form difunctional compounds are classified into sections on the basis of the two functional groups of the product. The relative positions... 

Attack of nucleophiles at the a-position of the enaminone predominates, leading to Michael addition which mostly results in substituted, mainly cyclic end-products. Also observed are subsequent amine elimination and reactions at the carbonyl. Some initial reactions of nucleophilic reagents at the enaminone carbonyl carbon are known. Enaminones are often better starting materials for several reactions than the corresponding dicarbonyls. As a result, a-aminomethylene ketones act as 1,3-biselectrophiles. Due to their combined electrophilic and nucleophilic properties, enaminones act as 1,3-bisnucleophiles as well. The assumed first step in the following reactions is the one used for classification of the reactions. In addition, enaminones are used as heterodienes in 4 + 2-cycloaddition mostly with electron-deficient dienophiles. 

In order to ensue a clear presentation of the results the authors decided to segregate both synthetic principles All synthetic strategies developed from the multifunctional condensations of Stille and Marvel were assigned to this general type of reaction. At the same time the first multistep sequences (polymer-analogous cyclization of poly(methyl vinyl ketone) and polyacrylonitrile) are used as point of reference for the classification of the other type of synthesis (stepwise procedures). 

The same classification is found in presence of photosensitizers. Poly-1 insolubilization above 290 nm is accelerated by nitro-2 fluorene, Michler s ketone and especially by xanthone. On the other hand when irradiation is carried out on films with additional 253.7 nm ray, nitrofluorene only gave an effect. The results obtained with the same sensitizers were similar in the case of Poly-3. The observations are quite different with Poly-2, the photochemical reaction of which is very sligthly improved by the presence of xanthone and greatly reduced by the two other compounds perhaps because of quenching effect. 

Thus, according to Sabatier the hydrogenations of olefins and ketones are the same type of reaction, while according to the multiplet classification these two reactions are of different types, and indeed, the two reaction types require two different catalysts. Naturally, in the application of a given classification the thermodynamic nature of the reactions should be taken into account as well as their structural aspects. This classification and thermodynamic requirements do not yet deal with the kinetics of processes. The latter is involved in the principles of structural and energetic correspondence of the multiplet theory. 

The classification is unaffected by allylic, vinylic, or acetylenic unsaturation appearing in both starting material and product, or by increases or decreases in the length of carbon chains for example, the reactions f-BuOH f-BuCOOH, PhCHgOH PhCOOH, and PhCH=CHCH20H PhCH=CHCOOH would all be considered as preparations of carboxylic acids from alcohols. Conjugate reduction and alkylation of unsaturated ketones, aldehydes, esters, acids, and nitriles have been placed in Sections 74D and 74E (Alkyls from Alkenes), respectively. 

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