Ester-acids => aldehydes

Hanssen, and Nair,127 and by Chadwick et a/.128 All deal with mono-, di-tri-, and sometimes tetra-substituted furans where the substituents are variously selected from halogen, ester, acid, aldehyde, and ketonic functions. Here we consider only some more special situations. 

Alkylcopper compounds, R—Cu, also are selective reagents that react with acid chlorides to give ketones, but do not add to esters, acids, aldehydes, or ketones. The R—Cu compounds can be prepared from Cul and the alkyl-lithium. With an excess of the alkyllithium, the alkylcopper is converted to R2CuLi ... 

In a mure specific definition, the carbon atom introduced originates from synthesis gas (CO/Hj) in a homogeneously-catalyzed liquid phase reaction. Substrates accessible for homologation are, in particular, alcohols but can also be ethers, esters.acids, aldehydes, and ketones [1"6]. 

Hydrogenation of carbon oxides with iron, cobalt, or nickel catalysts (Fischer-Tropsch process). Hydrocarbons are the main products Recovery and separation of oxygenated products obtained from CO and H2 Partial oxidation of nonaromatic hydrocarbon mixtures, e.g., petroleum, paraffins, and natural gas, to produce a mixture of products, such as esters, acids, aldehydes, ketones, and alcohols. This also includes higher fatty acids from petroleum and patents on formaldehyde production... 

We shall discuss further aspects of the aldol reaction in the next two chapters where we shall see how to control the enolisation of unsymmetrical ketones, and how to control the stereochemistry of aldol products such as 121. We shall return to a more comprehensive survey of specific enol equivalents in chapter 10. In this chapter we are concerned to establish that chemoselective enolisation of esters, acids, aldehydes, and symmetrical ketones can be accomplished with lithium enolates, enamines, or silyl enol ethers, and we shall be using all these intermediates extensively in the rest of the book. 

Because of its ability to determine surface chemistry, XPS can be particularly useful in the analysis of polymer surfaces to see if oxidation has taken place and, if so, what functional groups (e.g., ester, acid, aldehyde) the oxygen is present in. 

The lower members of other homologous series of oxygen compounds— the acids, aldehydes, ketones, anhydrides, ethers and esters—have approximately the same limits of solubility as the alcohols and substitution and branching of the carbon chain has a similar influence. For the amines (primary, secondary and tertiary), the limit of solubility is about C whilst for the amides and nitriles it is about C4. 

Sulfur tetrafluoride [7783-60-0] SF, replaces halogen in haloalkanes, haloalkenes, and aryl chlorides, but is only effective (even at elevated temperatures) in the presence of a Lewis acid catalyst. The reagent is most often used in the replacement of carbonyl oxygen with fluorine (15,16). Aldehydes and ketones react readily, particularly if no alpha-hydrogen atoms are present (eg, benzal fluoride [455-31-2] from benzaldehyde), but acids, esters, acid chlorides, and anhydrides are very sluggish. However, these reactions can be catalyzed by Lewis acids (HP, BF, etc). 

Several kinds of products can be obtained by reaction of thioglycolic acid and its esters with aldehydes to form mercaptals, RCH(SCH2COOH)2, or with ketones to form thiolketals, RR C(SCH2COOH)2. Reaction with formaldehyde (qv) yields di- -butyhnethylene-bisthioglycolate [1433882-0] (MET ester) ... 

Much work has been reported and summarized ia the Hterature on the matufing of various whiskeys ia charred or uncharred white-oak barrels (4—7). The early Hterature iadicates that total acids, aldehydes, esters, soHds, and color iacreased with aging time and that their concentrations were iaversely proportional to proof. Thus aging at higher proofs (over 127°) yields less color and flavor. The maximum allowable entry proof for straight whiskeys was iacreased from 110° to 125° by the U.S. Treasury Department ia 1962. 

Potassium carbonate. Solid potassium hydroxide is very rapid and efficient. Its use is limited almost entirely to the initial drying of organic bases. Alternatively, sometimes the base is shaken first with a concentrated solution of potassium hydroxide to remove most of the water present. Unsuitable for acids, aldehydes, ketones, phenols, thiols, amides and esters. Also used for drying gaseous amines and ammonia. 

Torlon-type polymers are unaffected by aliphatic, aromatic, chlorinated and fluorinated hydrocarbons, dilute acids, aldehydes, ketones, ethers and esters. Resistance to alkalis is poor. They have excellent resistance to radiation. If a total of 10 Mrad is absorbed at a radiation dosage of 1 Mrad/h the tensile strength decreases by only 5%. 

AkoJwIs may be obtained from aldehydes, ketones, esters, acid chlorides, and anhydrides,... 

The Fiesselmann reaction has been extensively used with p-halovinyl esters, ketones,aldehydes and nitriles as reaction partners for thioglycolic acid and its derivatives. This reaction with P-halovinyl aldehydes has been extensively explored as a result of the availability of P-chloro-a,P-unsaturated aldehydes via the Vilsmeier... 

Esters, like aldehydes and ketones, are weakly acidic. When an ester with an a- hydrogen is treated with 1 equivalent of a base such as sodium ethoxide, a reversible carbonyl condensation reaction occurs to yield a /3-keto ester. For example, ethyl acetate yields ethyl acetoacetate on base treatment. This reaction between two ester molecules is known as the Claisen condensation reaction. (We ll use ethyl esters, abbreviated "Et," for consistency, but other esters will also work.)... 

Addition of sulfonic acid esters to aldehydes or ketones... 

Hydrogenolysis of esters to aldehydes or alcohols needs high temperatures and high pressures. Moreover, it leads to the formation of acids, alcohols, and hydrocarbons. In contrast, bimetallic M-Sn alloys (M = Rh, Ru, Ni) supported on sihca are very selective for the hydrogenolysis of ethyl acetate into ethanol [181]. For example while the selectivity to ethanol is 12% with Ru/Si02, it increases up to 90% for a Ru-Sn/Si02 catalyst with a Sn/Ru ratio of 2.5 [182]. In addition, the reaction proceeds at lower temperatures than with the classical catalysts (550 K instead of temperatures higher than 700 K). The first step is the coordination of the ester to the alloy (Scheme 46), and most probably onto the tin atoms. After insertion into the M - H bond, the acetal intermediate decomposes into acetaldehyde and an ethoxide intermediate, which are both transformed into ethanol under H2. 

Santagada and coworkers have disclosed a reductive amination method for the generation of a reduced peptide bond by reaction of a protected amino acid aldehyde with an N-deprotected amino ester using sodium cyanoborohydride as reducing agent [296]. 

Grieco and coworkers have independently described the same type of Pictet-Spengler cyclization reactions involving tryptophan methyl ester and aldehydes, but using methanol as solvent and hydrochloric acid as a catalyst (microwave irradiation, 50 °C, 20-50 min) [416], Moderate to good product yields were obtained. 

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