PREPARATION OF ALDEHYDES

Yasuda, M. Shibata, I. Baba. A. Tetrahedron Lett., 2000, 41, 113. 

Cecchetto, A. Fontana, F. Minisci. F. Recupero, F. Tetrahedron Lett., 2001, 42, 6651. 

Shirini. F. Tajik, H. Aliakbar, A. Akbar, A. Synth. Commun., 2001, 31, Iffl. 

Romano, A. Gandolfi, R. Gargo, J.V.S. Molinari. F. Tetrahedron Lett 2002, 43,6059. C4H9CH2OH Cr03, solvent free, rt, 8h 

Punnivamurthv.T. Tetrahedron Lett. 2004,45,3561. PhI(OHOOTs, microwaves, neat 

90°C C8F17Br,CuBr SMe2,1.5h 

Ragagnin, G. Betzemeieer, B. Quici, S. Knochel. P. Tetrahedron 2002,58,3985. Magtriere, microwaves, 20 min 

Related Methods Ketones from Alcohols and Phenols (Section 168) 

Conjugate reductions and Michael alkylations of conjugated aldehydes are listed in Section 74 (Alkyls from Olefins). 

Review Alkylation of Ketones and Aldehydes via Nitrogen Derivatives  

Related Methods Aldehydes from Ketones (Section 57) 

TFMB = (trif1uoromethyl)benzenesulfonyl peroxide 77 Hoffman, R.V. Kumar, A. J Org Chan, (1984), 49, 4011 

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SECTION 50 ALDEHYDES FROM ALKYLS, METHYLENES, AND ARYLS 

Shibagaki, M. Takahashi, K. Matsushita, H. Bull. Chem. Soc. Jpn., 

TPCD = tetrakis-pyridino-cobalt dichromate = [Py4Co(HCi04)2J Hu. Y. Hu, H. Synth. Commun., 1992, 22, 1491. 

Tetrahedron Lett2002,43,6095. phCHjOH Mn02, solvent free, it 

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Small quantities of esters (in the above example n-hexyl n-caproate CH3(CHj)3COO(CH2)jCH3) are simultaneously formed. This is an excellent method for the preparation of aldehydes. 

The Gattermann-Koch formylatioii was found unsuited to the preparation of aldehydes from phenols and phenol ethers such aldehydes may be obtained by Gatteimann s aldehyde reaction. 

Ozonolysis has both synthetic and analytical applications m organic chemistry In synthesis ozonolysis of alkenes provides a method for the preparation of aldehydes and ketones... 

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... 

The oxidation of alcohols by treatment of their corresponding chloroform-ates with DMSO and triethylamine has been reported by Barton. Preliminary results indicate this to be a useful method for preparation of aldehydes but cyclic secondary alcohols are converted to ketones in relatively low yields. 

The calcium salt is used in the preparation of aldehydes by beating it with the calcium salt of a higher aliphatic acid,... 

Hiese unsaturated esters, hy oxidation, permit of the elimination of the CHO group and the preparation of aldehydes or acids with fewer oarbon atoms. 

The procedure described is a modification of the general procedure of Angyal2 for the preparation of aldehydes from benzylamines by the Sommelet reaction. Isophthalaldehyde has been prepared from w-xylene by preparation of the tetrachloro derivative and hydrolysis,3 from isophthaloyl chloride by the Rosenmund reaction,4 from a,a -dibromo-m-xylene by the Sommelet reaction,5 and from isophthaloyl chloride by reduction with lithium tri-Cbutoxyaluminumhydride.6... 

The reaction is an important step in a method for the oxidative decyanation of nitriles containing an a hydrogen. The nitrile is first converted to the a-hydro-peroxy nitrile by treatment with base at — 78°C followed by O2. The hydroperoxy nitrile is then reduced to the cyanohydrin, which is cleaved (the reverse of 16-51) to the corresponding ketone. The method is not successful for the preparation of aldehydes (R =H). 

Preparation of Aldehydes and Ketones from Thio- and Selenoethers... 

The general mechanistic features of the aldol addition and condensation reactions of aldehydes and ketones were discussed in Section 7.7 of Part A, where these general mechanisms can be reviewed. That mechanistic discussion pertains to reactions occurring in hydroxylic solvents and under thermodynamic control. These conditions are useful for the preparation of aldehyde dimers (aldols) and certain a,(3-unsaturated aldehydes and ketones. For example, the mixed condensation of aromatic aldehydes with aliphatic aldehydes and ketones is often done under these conditions. The conjugation in the (3-aryl enones provides a driving force for the elimination step. 

The stereospecific preparation of aldehyde ester 462, already comprising five of the six stereo centers of the molecule and, furthermore, the stereoselective construction of the epialloyohimbane skeleton with Ec2 conformation are regarded the remarkable features of Woodward s approach. 

In a 3-I. round-bottomed flask fitted with a 3-ft. indented column to which is attached a condenser set for downward distillation are placed 321 g. (3 moles) of methylaniline, 300 g. of formic acid (85-90 per cent), and 1800 cc. of toluene (Note 1). The solution is distilled slowly. As long as the azeotrope containing water is present, the temperature of the vapor is 87-88° when the water has been removed, the temperature rises to 108-110° (Note 2). The distillation is continued until approximately 1500 cc. of toluene has been collected (five to six hours). The residue is then transferred to a modified Claisen flask (Org. Syn. Coll. Vol. 1, 125) and distilled in vacuo, the portion boiling at 114-121° at 8 mm. being collected. This has a freezing point of 13.6-13.7° d i-5S3 I SSS- The yield is 380-393 g. (93-97 per cent of the theoretical amount). This product is satisfactory for the preparation of aldehydes (p. 11). Upon redistillation it boils at 117-121° at 8 mm., 130-132° at 22 mm. The freezing point and refractive index are unchanged. 

IPreparation of Mldehydes Some important methods for the preparation of aldehydes and Ketones and ketones are as follows ... 

Reduction of cuprous chloride with sodium borohydride gives copper hydride which is a highly selective agent for the preparation of aldehydes from acyl chlorides [775]. 

Another hydride for the preparation of aldehydes from acyl chlorides is obtained by treatment of a mixture of cuprous chloride and triphenylphos-phine, trimethyl phosphite or triisopropyl phosphite in chloroform with an ethanolic solution of sodium borohydride. Such reagents reduce acyl chlorides to aldehydes in acetone solutions at room temperature in 15-90 minutes in yields ranging from 57% to 83% [115],... 

Reduction of amides to aldehydes was accomplished mainly by complex hydrides. Not every amide is suitable for reduction to aldehyde. Good yields were obtained only with some tertiary amides and lithium aluminum hydride, lithium triethoxyaluminohydride or sodium bis 2-methoxyethoxy)aluminum hydride. The nature of the substituents on nitrogen plays a key role. Amides derived from aromatic amines such as JV-methylaniline [1103] and especially pyrrole, indole and carbazole were found most suitable for the preparation of aldehydes. By adding 0.25 mol of lithium aluminum hydride in ether to 1 mol of the amide in ethereal solution cooled to —10° to —15°, 37-60% yields of benzaldehyde were obtained from the benzoyl derivatives of the above heterocycles [1104] and 68% yield from N-methylbenzanilide [1103]. Similarly 4,4,4-trifluorobutanol was prepared in 83% yield by reduction of N-(4,4,4-trifluorobutanoyl)carbazole in ether at —10° [1105]. 

Of the methods used for converting amides to aldehydes the one utilizing lithium triethoxyaluminohydride is most universal, can be applied to many types of amides and gives highest yields. In this way it parallels other methods for the preparation of aldehydes from acids or their derivatives (p. 148). 

DESULFURIZATION WITH RANEY NICKEL Preparation of Aldehydes from Thiol Esters [1101]... 

The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of hydrogen and carbon monoxide. The most extensive use of the reaction is in the preparation of normal- and iso-butyraldehyde from propylene. The ratio of the amount of the normal aldehyde product to the amount of the iso aldehyde product typically is referred to as the normal to iso (N I) or the normal to branched (N B) ratio. In the case of propylene, the normal- and iso-butyraldehydes obtained from propylene are in turn converted into many commercially-valuable chemical products such as n-butanol, 2-ethyl-hexanol, trimethylol propane, polyvinylbutyral, n-butyric acid, iso-butanol, neo-pentyl glycol,... 

Slaugh and Mullineaux (1) disclosed a low pressure hydroformylation process using trialkylphosphines in combination with rhodium catalysts for the preparation of aldehydes as early as 1966. Trialkylphosphines have seen much use in industrial hydroformylation processes but they typically produce a limited range of products and frequently are very oxygen sensitive. 

Addition of water to alkynes preparation of aldehydes and ketones... 

Hydroboration-oxidation of alkynes preparation of aldehydes and ketones Hydroboration-oxidation of terminal alkynes gives syn addition of water across the triple bond. The reaction is regioselective and follows anti-Markovnikov addition. Terminal alkynes are converted to aldehydes, and all other alkynes are converted to ketones. A sterically hindered dialkylborane must be used to prevent the addition of two borane molecules. A vinyl borane is produced with anU-Markovnikov orientation, which is oxidized by basic hydrogen peroxide to an enol. This enol tautomerizes readily to the more stable keto form. 

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