Functional group carbonyl groups

Sugars contain an aldehyde or ketone functional group (carbonyl group, C=0) as well as several hydroxyl groups (—OH). 

The selection rule for IR spectroscopy is that for absorption to occur, the molecular dipole must change during the course of the vibration. Thus, simple diatomic molecules such as Oj do not absorb. The most intense absorptions involve polar functional groups—carbonyl groups absorb more strongly than alkenes, and nitriles more strongly than alkynes. 

Trifluoromethyl)trimethylsilane has been prepared by a modification5 of the procedure originally published by Ruppert.4 The optimized yield is 75%. Other less convenient methods are also available for its preparation. (Trifluoromethyl)trimethylsilane acts as an in situ trifluoromethide equivalent under nucleophilic initiation and reacts with a variety of electrophilic functional groups. Carbonyl compounds such as aldehydes, ketones and lactones react rather readily5 7 with (trifluoromethyl)trimethylsilane under fluoride initiation. The reagent also reacts with oxalic esters,8 sulfonyl fluorides,9 a-keto esters,10 fluorinated ketones,11 and... 

When a 1,2,4-trioxolane has a side chain containing a ketone or aldehyde, it is possible to selectively functionalize the carbonyl group, leaving the trioxolane intact. Examples of such reactions... 

In creating synthetic routes for the development of drug molecules, the synthetic chemist wants to create a molecular entity in which functional groups (carbonyls, amines, etc.) are correctly positioned in three-dimensional space this will enable the creation of functional biophoric fragments such as the pharmacophore. The synthetic chemist has ten general classes of reactions available for such synthetic tasks ... 

Alkanes Most compounds have an alkyl part and therefore have absorption bands in the 3000-2850 crrT1 region due to their CH bonds.The feature that distinguishes alkanes is the absence of bands for hydroxy groups, carbonyl groups, and so on.The spectrum of an alkane usually has many fewer absorptions than those of compounds with other functional groups. 

The relative reactivity of the alcohol and amine in the example just given could be overturned by conducting a reaction under thermodynamic control. In kinetically controlled reactions, the idea that you can conduct chemoselective reactions on the more reactive of a pair of functional groups— carbonyl-based ones, for example—is straightforward. But what if you want to react the less reactive of the pair There are two commonly used solutions. The first is illustrated by a compound needed by chemists at Cambridge to study an epoxidation reaction. They were able to make the following diol, but wanted to acetylate only the more hindered secondary hydroxyl group. 

Since monosaccharide.s contain only two kinds of functional groups, carbonyls and hydroxyls, most of the chemistry of monosaccharides is the now familiar chemistry of these two groups. 

We now turn to two reactions, the McMurry and metathesis, that have the same disconnection but both reagents have identical functional groups carbonyls for the McMurry and alkenes for metathesis. These methods have the advantage of simplicity but there are obvious problems of selectivity. 

Fig. 7. Turnover in binding mode (i) vs T ) as a function of carbonyl group...

Moreover, NMR was revolutionary in provoking a Gestalt switch (to borrow Kuhn s phraseology) in the chemists perceptions. Earlier, molecules were identified by their functional groups, carbonyls, hydroxyls, and the like, which were like beacons (as reflected in chemical nomenclature, in its affixes and priorities). Now, especially at the beginning of... 

Semiempirical MNDO computations suggest an intramolecular H-bonding interaction between the NH function and carbonyl group, resulting in a pre-ori-ented CO function. The computations also support a stereochemical model which correctly reproduces the sense of selectivity for the acetylide transfer within the ketone-coordinated, mixed 2 2 aggregate (30) [88]. 

After protection of the alcohol function, the carbonyl group is converted into a methylene group by means of the Tebbe reagent, followed by a Swern oxidation and a Homer-Wadsworth-Emmons reaction. 

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