Carbonyl compound, analysis

Analysis the functional group is an acetal derived fiom alcohols and a carbonyl compound. 

Before we complete the disconnections of carbonyl compounds we shall look at some aspects of control in synthesis as a break from the systematic analysis. 

The Michael reaction plays a part in some more extended synthetic sequences of great importance. Analyse TM 116 as an a,p-unsaturated carbonyl compound and continue your analysis by the Michael reaction. 

Analysis Another lactone FGl reveals the true TM (A). Our normal discormection a of an a,p-unsaturated carbonyl compound gives us the 1,5-dicarbonyl compound (B) and the ketone (C) clearly derived from phenol. Alternatively we could disconnect bond b to the keto-ester (D) with the further discormection shown ... 

Alkenes are cleaved to carbonyl compounds by ozonolysis This reaction IS useful both for synthesis (preparation of aldehydes ketones or car boxyhc acids) and analysis When applied to analysis the carbonyl com pounds are isolated and identified allowing the substituents attached to the double bond to be deduced... 

Figure 13,12 Illusti ation of the clean-up method, showing the analysis of an air sample (a) with and (b) without column switching. Details of the analytical conditions are given in the text. Reprinted from Journal of Chromatography, A 697, R R. Kootsti a and H. A. Herbold, Automated solid-phase exti action and coupled-column reversed-phase liquid cltromatogra-phy for the trace-level determination of low-molecular-mass carbonyl compounds in ak , pp. 203-211, copyright 1995, with permission from Elsevier Science.

For a detailed transition state analysis of the reactions of allylorganometallic reagents and carbonyl compounds ... 

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

In a, P-unsaturated carbonyl compounds and related electron-deficient alkenes and alkynes, there exist two electrophilic sites and both are prone to be attacked by nucleophiles. However, the conjugated site is considerably softer compared with the unconjugated site, based on the Frontier Molecular Orbital analysis.27 Consequently, softer nucleophiles predominantly react with a, (i-unsaturated carbonyl compounds through conjugate addition (or Michael addition). Water is a hard solvent. This property of water has two significant implications for conjugate addition reactions (1) Such reactions can tolerate water since the nucleophiles and the electrophiles are softer whereas water is hard and (2) water will not compete with nucleophiles significantly in such... 

If, on the other hand, unsymmetrically substituted carbonyl compounds such as monosubstituted benzophenones (X = OCH3, CH3, Cl), tert-butyl methyl ketone, acetophenone, acetaldehyde, or benzaldehyde are used for trapping 39a, diastere-omeric mixtures are formed in each case they could all be resolved except for the products obtained with p-methoxybenzophenone and acetophenone 33>. An X-ray structure analysis has been performed for the E-isomer 57g 36) which, in conjunction with H-NMR studies, permitted structural assignment in cases 56 and 57e, g and h35>. Additional chemical evidence for the structure of the six-membered heterocycles is provided by the thermolysis of 56 a considered in another context (see Sect. 3.1). In general the reaction 39a- 56 or 57 is accompanied by formation of phosphene dimers, presumably via [4 + 4]- and via [4 + 2]-cycloaddition 35). 

We have intentionally selected example reactions (Figs. 29-33) that would not usually be immediately obvious to a chemist. The examples chosen have all been concerned with rearrangements of various types, since their courses are frequently difficult to predict. It remains to emphasize that the reactivity functions contained in EROS perform perfectly well with other types of reaction. This is true, for example, with reactions that a chemist could derive directly from an analysis of the functional groups in a molecule. Thus, EROS predicts addition reactions to carbonyl compounds, nucleophilic substitutions, and condensation reactions, to name just a few examples. In all these reaction types, the possibility of assigning a quantitative estimate to the reactivity at the various sites via the reactivity functions is of particular merit. It... 

Treatment of the CH-acidic carbonyl compound with 1.5-2.5 equivalents of D M F D EA in N, N-dimethylformamide at 180 °C resulted in full conversion to the enam-ine synthons within 5 min. The enamines were obtained in 53-93% yield (based on LC-MS analysis) and were used without further purification in the next step. 

TBA-F.3H20 (20 mg, 0.063 mmol) is added to the carbonyl compound (10 mmol) and the trimethylsilyl compound (12 mmol) in THF (25 ml) at 0°C. The mixture is allowed to come to room temperature and is stirred until the reaction is complete (ca. 1 h), as shown by GLC analysis. Aqueous HC1 (1 M, 5 ml) is added and the mixture is stirred until all of the silane has been hydrolysed (1-15 h). The aqueous mixture is extracted with Et20... 

A molecular sieves (0.5 g) and polymer-supported perruthenate (0.1 g), prepared by adding KRu04 (10 mg, 1 mmol) to Amberlyst IR-27 resin (1 g), in CH2C12 or MeCN (5 ml) at room temperature until TLC analysis indicates complete consumption of the alcohol (ca. 16 h). The mixture is filtered and the filtrate evaporated to yield the carbonyl compound [e.g. PhCHO, >95% (16 h) PhCH=CHCHO, >95% CH2=CH(CH2)2CHO, 62% n-C7HI5CHO, 54% cyclohexanone, 50%]. The resin can be reused without loss of activity. 

ZrCl2 (0.28 g) is added to HC=CC02Me (84 mg, 1 mmol), the carbonyl compound (1.2 mmol) andTBA-I (0.4 g, 1.1 mmol) in CH2CI2 (5 ml) with stiningat 0°C. When the reaction is complete, as shown by TLC analysis, H20 (5 ml) is added and the mixture is extracted with CH2C12 (3x5 ml). The dried (MgS04) extracts are evaporated to yield the iodopropenol. 

Chromatogram of the analysis of carbonyl compounds by the 2,4-DNPEFs methods A standard mixture, B rendering emissions... 

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