Aldehydes from anhydrides

Arylzinc species prepared via the sacrificial anode process and from aryl halides in the presence of a nickel 2,2 -bipyridine, as already reported in Section . .1, were found totally unreactive towards common electrophiles such as aldehydes, carboxylic anhydrides or activated alkyl halides. However, they react with some electrophiles when they are activated by the presence of a catalytic amount of copper salts (10 mol% Cul) together with tetramethylethylene diamine (1MEDA) as described by Knochel and Singer on the ArZnX—CuCN metal exchange47 or when the reaction is catalyzed by palladium complex. 

The activation of DMSO by electrophilic reagents such as oxallyl chloride or trifluoroacetic anhydride (TFAA) (among many others) produces an oxidant capable of oxidizing primary alcohols to aldehydes in high yields. This oxidation is called the Swern oxidation and yields the aldehyde (oxidized product) by reductive elimination of dimethylsulfide (reduced product) and proceeds under mild, slightly basic conditions. It is a second widely used and effective oxidative method for the production of aldehydes from primary alcohols. 

Enols or enolates from anhydrides are not used very often in aldol reactions other than in one important application, usually known as the Perkin reaction. An acid anhydride, such as acetic anhydride, is combined with a non-enolizable aldehyde and a weak base, usually the salt of the acid. This base is used so that nucleophilic attack on the anhydride does no hami, simply regenerating the anhydride. q... 

It appears that in most cases the FFB is the reactor of choice whenever exothermic heat is great, or when selectivity is of importance, or when high capacity is the goal. Other processes, such as phthalic anhydride by oxidizing oxylene with air, and unsaturated aldehydes from an unsaturated olefine, are also reported to use FFB reactors. 

Acetic formic anhydride has been prepared by the reaction of formic acid with acetic anhydride2 3 and ketene,4,5 and of acetyl chloride with sodium formate.6 The present procedure is essentially that of Muramatsu.6 It is simpler than others previously described and gives better yields. It is easily adapted to the preparation of large quantities, usually with an increase in yield. Acetic formic anhydride is a useful intermediate for the formyl-ation of amines,3,7 amino acids,8,9 and alcohols,2,10 for the synthesis of aldehydes from Grignard reagents,11 and for the preparation of formyl fluoride.12... 

Other recent repiorts of the automated synthesis of SP libraries of discretes include those of Wilson et al. (166), who prepared a library of more than 1000 aminohydantoins from a-hydrazino amino acids, amines, and aldehydes Perumattam et al. (167), who reported a 200-member library based on an anhydride template using anhydrides, primary amines, and a-amino acids Smith et al. (168), who described the synthesis of a library of more than 1000 piperazinediones from a-amino acids Crawshaw et al. (169), who presented a >200-member Ubrary of cyclohexanones from maleimides, nitrostyrenes, and aminobutadienes Shao et al. (170), who described a 96-member library of quina-zolinediones from anhydrides and amines Lebl et al. (21), presenting a 30,816-member... 

ACD is a skin reaction resulting from contact dermal contact with allergens. ACD progresses in two phases. Sensitization is acquired in the initial phase. In the second phase, subsequent exposure elicits an inflammatory reaction. F°1 Large numbers of chemical compounds are known to cause ACD. These include acrylates, aldehydes, amines, anhydrides, etha-nolamines, formaldehyde, resins, metals, pesticides, phenols, phthalate esters, preservatives, isocyanates, solvents, and others. Table 27.4 contains a partial list of these. A more complete list can be found on the webJ21l... 

CrOi-acetic anhydride-H Ot (Thiele reagent). This powerful reagent converts an arylmethyl compound into the diaeetate of an aldehyde, from which the aldehyde can be recovered by acid hydrolysis ... 

Further studies on the reactions of anhydrides with carboxylic acids in the presence of a palladium catalyst led to the discovery of the direct hydrogenation of carboxylic acids into aldehydes. The catalytic process provides new means of synthesizing various aldehydes from carboxylic acids (Eq. 31) [77]. 

Although little experimental data is available, numerous patents have been issued for the vapor phase catalytic oxidation of various other derivatives containing the benzene nucleus, as well as heterocyclic compounds Thus, fluorene (diphenyl methane) is oxidized to fluorenone with air in the presence of a catalyst containing iron vanadate or other suitable metal salt of the fifth or sixth group of the periodic system at a temperature of 360° to 400°.1,2 Maleic acid and anhydride are formed by the catalytic oxidation of compounds of the furan series, such as furan, furfural alcohol, furfural, methyl furfural, hydroxymethylfurfural, pyromucic acid or mixtures, with air over catalysts of molybdenum, vanadium, or other metals.133 Dimethyl benzaldehyde is formed by oxidizing pseudocumene with air at 550° C. in the presence of a tungsten oxide catalyst. Molybdenum, vanadium, or tantalum oxide catalysts may also be used to form aromatic aldehydes from o-, m-, or p-xylenes, mesitylene, p-cymene, or o-chlorotoluene by air oxidation. Times of contact of 0.3 to 0.4 seconds... 

In treating of the monoatomio compounds, it was stated that substances existed corresponding to the fatty acids, known as aldehydes and anhydrides, the former differing from the acids in that they contained the group COH instead of OOOH tbe latter being the oxides of the acid radicMkls. Similar compounds exist correspondi to the acids of these two series. 

Aldehydes from carboxylic acids. Japanese chemists have reported the synthesis of aldehydes or aldehydic acids from carboxylic anhydrides using this reagent. Yields are in the range of 30-90%. 

An alternative route to aldehydes from carboxylic acids involves conversion of the acid into the carboxylic ethylcarbonic anhydride (1) by reaction with ethyl chloroformate. These anhydrides react with sodium tetracarbonylferrate... 

Phosphinic acid anhydrides and aldehydes from phosphinic acid esters and 1,1-dihalides... 

Aldehydes from carboxylic acids via carboxylic alkoxyformic anhydrides... 

What roles do inorganic catalysts play in the following manufacturing processes (a) production of aldehydes from alkenes, (b) polymerization of propene, (c) production of acetic anhydride,... 

Important uses of selenenic and seleninic acids and anhydrides (see also the later sections) have been established, in the synthesis of )ff-silyloxy-a-(phenyl-seleno)aldehydes from allyl silyl ethers (Scheme 3) and in the high-yield syntheses of 2-acetoxyalkyl phenyl selenides [using PhSe(0)OH and AcOH j and... 

Section 47 Aldehydes from Carboxylic Acids, Acid Halides and Anhydrides u u ac ov B O ero gg fl C OPouo-go feooaooaegagoeBBeoooaooegquuooo ou ti o o ra g o... 

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