Acetaldehyde dialkyl acetals

Benzo[6]thioi>henes by Ring-Closure op (Arylthio)acetaldehyde Dialkyl Acetals [Eq. (4)]... 

In contrast to the addition of water, the addition of alcohols to alkynes leads to stable enol ethers. Those of economic importance are almost exclusively the vinyl ethers prepared from acetylene. This preparation is carried out under base catalysis [41] (KOH, alcoholates, and the like). The noble metal-catalyzed alcohol addition does in fact likewise lead, in an intermediate stage, to vinyl ethers, but these react under the prevailing conditions, generally in a quantitative reaction, to give to corresponding acetaldehyde dialkyl acetals [42]. This is illustrated in (eq. (18)), which takes as its example the addition of n-butanol to acetylene in the presence of Na2PtCl6. 

Acenaphtho[ 1,2-e][ 1,2,4]triazines synthesis, 3, 434 Acenaphthylene episulfide synthesis, 7, 181 Acenocoumarol application, 3, 881 Acetaldehyde ethylhydrazone NMR, 2, 117 Acetaldehyde, arylthio-dialkyl acetals... 

Cyclic acetals of ketoses are prepared most commonly from acetone or benzaldehyde formaldehyde, acetaldehyde, butanone, and cyclohexanone have been used occasionally. These carbonyl reagents are frequently used directly, although such derivatives as 2,2-di-methoxy- or 2,2-diethoxy -propane (acetone dialkyl acetals), or l,l-dimethoxyethane (acetaldehyde diethyl acetal), are often employed in experiments in which intermediate acetals are of interest,or in which the presence of water in the reaction mixture adversely affects the yield of products. A polymeric form of an aldehyde is the reagent to be preferred whenever the monomer is volatile for example, acetaldehyde is often used in the form of a trimer, paraldehyde, and formaldehyde is employed as formalin solution, as paraformaldehyde, or as polyoxymethylene. An excess of the carbonyl reagent is generally used as the solvent, and the condensation is usually effected at room temperature. 

The phosphonylation of haloacetaldehyde diethyl acetals coupled with a smooth hydrolysis of the acetals has been applied with success to the preparation of phosphonylated acetaldehydes and is particularly useful on a large scale.Unfortunately, this procedure cannot be extended to the synthesis of a-substituted dialkyl I -fonnylmethylphosphonatcs." ... 

Simple derivatives of (a-hydroxyalkyl)phosphonic and analogous acids have been obtained directly by procedures analogous to those adopted for the parent compounds. Thus, O-acetates of (2,2,2-trichloro-l-hydroxyethyl)phosphonic acid esters have been prepared through the interaction of the appropriate halogenated acetaldehyde and phosphorous-acetic acid anhydrides An aromatic aldehyde and dialkyl phospho-roisocyanatidite in the presence of water or an alcohol yields analogous 0-carbamoyl derivatives of (a-hydroxybenzyl)phosphonic diesters, probably through cyclic intermedi-ates ". ... 

The treatment of a 2-(dialkoxyphosphinoyl)acetaldehyde with a mixture of acetic anhydride and nitric acid (effectively acetyl nitrate) containing a trace of sulphuric acid leads to very low yields to the dialkyl (nitromethyl)phosphonate, and a better procedure consists in the nitration of an enol ether of the acetaldehyde 84 (R = OR) with R =... 

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