Alcohol to aldehydes

Oxidation if 1° and 2° alcohols to aldehydes and ketones- No over oxidation... 

The Dess-Martin periodinane ( DMP ) reagent, U,l-tris(acetyloxy)-l,l-dihydro-l,2-benziodoxol-3(l//)-one, has also been used in several complex syntheses for the oxidation of primary or secondary alcohols to aldehydes or ketones, respectively (e.g., M. Nakatsuka, 1990). It is prepared from 2-iodobenzoic add by oxidation with bromic add and acetylation (D.a Dess, 1983). 

The mechanisms by which transition metal oxidizing agents convert alcohols to aldehydes and ketones are complicated with respect to their inorganic chemistry The organic chemistry is clearer and one possible mechanism is outlined m Figure 15 4 The... 

Section 15 11 Oxidation of alcohols to aldehydes and ketones is a common biological reaction Most require a coenzyme such as the oxidized form of nicotin amide adenine dmucleotide (NAD" )... 

To the synthetic chemist the most important of the reactions m Table 17 1 are the last two the oxidation of primary alcohols to aldehydes and secondary alcohols to ketones Indeed when combined with reactions that yield alcohols the oxidation methods are so versatile that it will not be necessary to introduce any new methods for preparing aide hydes and ketones in this chapter A few examples will illustrate this point... 

Alcohol dehydrogenase (Section 15 11) Enzyme in the liver that catalyzes the oxidation of alcohols to aldehydes and ke tones... 

Pauli exclusion principle (Section 1 1) No two electrons can have the same set of four quantum numbers An equivalent expression is that only two electrons can occupy the same orbital and then only when they have opposite spins PCC (Section 15 10) Abbreviation for pyndimum chlorochro mate C5H5NH" ClCr03 When used in an anhydrous medium PCC oxidizes pnmary alcohols to aldehydes and secondary alcohols to ketones... 

Addition of water or alcohols to aldehydes leads to the formation of a class of compounds known as acetals. This is an acid cataly2ed reaction... 

This ladical-geneiating reaction has been used in synthetic apphcations, eg, aioyloxylation of olefins and aromatics, oxidation of alcohols to aldehydes, etc (52,187). Only alkyl radicals, R-, are produced from aliphatic diacyl peroxides, since decarboxylation occurs during or very shortiy after oxygen—oxygen bond scission in the transition state (187,188,199). For example, diacetyl peroxide is well known as a source of methyl radicals (206). 

V-bromosuccinimide [128-08-5] C H BrNOj 180-183 2.098 brominating olefins, oxidizing alcohols to aldehydes and ketones, converting aldehydes to acid bromides... 

DESS - MARTIN Oxidizing Reagent Oxidation of alcohols to aldehydes or ketones by means of penodinanes. 

SECTION 8.1. HYDRATION AND ADDITION OF ALCOHOLS TO ALDEHYDES AND KETONES... 

If homolytic reaction conditions (heat and nonpolar solvents) can be avoided and if the reaction is conducted in the presence of a weak base, lead tetraacetate is an efficient oxidant for the conversion of primary and secondary alcohols to aldehydes and ketones. The yield of product is in many cases better than that obtained by oxidation with chromium trioxide. The reaction in pyridine is moderately slow the intial red pyridine complex turns to a yellow solution as the reaction progresses, the color change thus serving as an indicator. The method is surprisingly mild and free of side reactions. Thus 17a-ethinyl-17jS-hydroxy steroids are not attacked and 5a-hydroxy-3-ket-ones are not dehydrated. 

Oxidation of primary alcohols to aldehydes (Section 15.10) Pyridinium dichromate (PDC) or pyridinium chloro-chromate (PCC) in anhydrous media such as dichloromethane oxidizes primary alcohols to aldehydes while avoiding overoxidation to carboxylic acids. 

Aldehydes are more easily oxidized than alcohols, which is why special reagents such as PCC and PDC (Section 15.10) have been developed for oxidizing primary alcohols to aldehydes and no further. PCC and PDC are effective because they are sources of Cr(VI), but are used in nonaqueous media (dichloromethane). By keeping water out of the reaction mixture, the aldehyde is not converted to its hydrate, which is the necessary intermediate that leads to the carboxylic acid. 

PCC (Section 15.10) Abbreviation for pyridinium chlorochro-mate CjHjNIT ClCr03. When used in an anhydrous medium, PCC oxidizes primary alcohols to aldehydes and secondary alcohols to ketones. 

Perhaps the most important reaction of alcohols is their oxidation to carbonyl compounds. Primary alcohols yield either aldehydes or carboxylic acids, secondary alcohols yield ketones, but tertiary alcohols are not normally oxidized. Pyridinium chlorochromate (PCC) in dichloromethane is often used for oxidizing primary alcohols to aldehydes and secondary alcohols to ketones. A solution of Cr03 in aqueous acid is frequently used for oxidizing primary alcohols to carboxylic acids and secondary alcohols to ketones. 

Complexes [Ru30(0Ac)6L3]"+ (L = H20, PPh3) have been found to be catalysts for the oxidation of primary and secondary alcohols to aldehydes and ketones under fairly mild conditions (65°C, 3 atm 02) with high catalytic turnovers [104],... 

Dipyridiue-chromium(VI) oxide2 was introduced as an oxidant for the conversion of acid-sensitive alcohols to carbonyl compounds by Poos, Arth, Beyler, and Sarett.3 The complex, dispersed in pyridine, smoothly converts secondary alcohols to ketones, but oxidations of primary alcohols to aldehydes are capricious.4 In 1968, Collins, Hess, and Frank found that anhydrous dipyridine-chromium(VI) oxide is moderately soluble in chlorinated hydrocarbons and chose dichloro-methane as the solvent.5 By this modification, primary and secondary alcohols were oxidized to aldehydes and ketones in yields of 87-98%. Subsequently Dauben, Lorber, and Fullerton showed that dichloro-methane solutions of the complex are also useful for accomplishing allylic oxidations.6... 

Oxidation of Primary Halides and Esters of Primary Alcohols to Aldehydes ... 

The complex Pd-(-)-sparteine was also used as catalyst in an important reaction. Two groups have simultaneously and independently reported a closely related aerobic oxidative kinetic resolution of secondary alcohols. The oxidation of secondary alcohols is one of the most common and well-studied reactions in chemistry. Although excellent catalytic enantioselective methods exist for a variety of oxidation processes, such as epoxidation, dihydroxy-lation, and aziridination, there are relatively few catalytic enantioselective examples of alcohol oxidation. The two research teams were interested in the metal-catalyzed aerobic oxidation of alcohols to aldehydes and ketones and became involved in extending the scopes of these oxidations to asymmetric catalysis. 

---