Acetylenic ethers, oxidation

Zinc enolate 4, prepared from acetylene ether pyridine i-oxide, mercuric chloride, and zinc, adds to aldehydes to form a-chloro-3-hydroxy esters 5 in good yields ( ). Subsequent treatment with base gives trans-epoxyesters, one of which 6 is converted to 2-amino-2-deoxy-D-ribose stereoselectively in good yields (O. 

Unsaturated esters can be prepared from the corresponding acetylenic ethers with yields in most cases of >50%. 0-Hydroxyethyl esters can be prepared from carboxylic acids and ethylene oxide. 

Ether solutions of magnesium cuprates undergo 1,4-additions to acetylenic phosphine oxides or sulfides, unlike organolithium reagents... 

Oxidation of acetylenic ethers. 1-Alkoxy-l-alkynes (1) are oxidized by OSO4 (the function of KCIO3 is to regenerate OsO ) to a-keto esters (2) in HjO-ether in 50-80% yield. The paper also reports use of this system for the novel oxidation of 3 to the erythro-isomcT (4) of 3,4-dihydroxyhexane-2,5-dione. ... 

The procedures used most often for preparation of arylsulfonyl acetylenes Involve oxidation of the corresponding ethynyl thio ether. The thio ethers are usually obtained via a two-step sequence beginning with two-fold thiophenoxide displacement of chloride ion from cis-l,2-dichloroethylene, followed by elimination with n-butyl1ithium in the resultant cis-1,2-bisarylthioethylene. Less well known methods involve diazotization of 4-arylsulfonyl-5-aminoisoxazoles, dehydrobrpmination of cis- and trans-2-bromovinyl phenyl sulfone with fluoride ion, and oxidative elimination of - phenylseleno)vinyl sulfones. The method described here, which bypasses the need for strongly basic conditions, is adapted from the work of Bhattacharya, Josiah, and Walton. The simplicity and mildness of the method suggest that it may be broadly useful. 

EXPLOSION and FIRE CONCERNS nonflammable gas, but strong oxidizer NFPA rating Health 4, Flammability 0, Reactivity 0 reacts explosively with acetylene, ether, turpentine, ammonia, fuel gas, hydrogen, and finely divided metals reacts violently with many alcohols explodes on contact with molten aluminum, ammonia, benzene, bromine pentafluoride, diborane, and many others combines with moisture to form reactive hydrogen chloride gas use water spray or fog for firefighting purposes. 

Aliphatic or aromatic aldehydes react with (ethoxycarbonyliodomethyl)triphenyl-phosphorane (183) in the presence of potassium carbonate in a two-phase liquid-solid system to give acetylenic esters 184 . Pyrolysis of a-halophosphoranes 185 (X = Cl or Br R = Ar or t-Bu) results in 1-haloalkynes 186. Vacuum pyrolysis of the betaine 188, formed from the phenoxymethylenephosphorane 187, yields the acetylenic ether 189 Flash-vacuum pyrolysis of the phosphorane 190 at 750°C gives triphenylphosphine oxide and phenylacetylene with elimination of the ethoxycarbonyl groups... 

For example, carbon dioxide from air or ethene nitrogen oxides from nitrogen methanol from diethyl ether. In general, carbon dioxide, carbon monoxide, ammonia, hydrogen sulfide, mercaptans, ethane, ethene, acetylene (ethyne), propane and propylene are readily removed at 25°. In mixtures of gases, the more polar ones are preferentially adsorbed). 

Flammable gases and vapors include acetylene, hydrogen, butadiene, ethylene oxide, propylene oxide, acrolein, ethyl ether, ethylene, acetone, ammonia, benzene, butane, cyclopropane, ethanol, gasoline, hexane, methanol, methane, natural gas, naphtha, and propane. 

Dehydrochlorination of bis(tnfluoromethylthio)acetyl chloride with calcium oxide gives bis(trifluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chloride or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [6 (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluoride-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene in acetonitrile from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

Ca/NH3, ether or THE, 2 h NH4CI, H2O. 90% yield. Acetylenes are not reduced under these conditions. One problem with the use of calcium is that the oxide coating makes it difficult to initiate the reaction. This is partially overcome by adding sand to the reaction mixture to abrade the surface of the calcium mechanically. 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 45, 71 Sodium amide, in alkylation of ethyl phenylacetate w ith (2-bromo-ethyl)benzene, 47, 72 in condensation of 2,4-pentanedione and 1 bromobutane to give 2,4-nonanedione, 47, 92 Sodium 2 ammobenzenesulfinate, from reduction of 2 mtrobenzenesul-finic acid, 47, 5... 

R = Me, R = H) with cyclohexenol in the presence of F ion followed by NaOCl oxidation gave the tricyclic ether 61 in 65% yield (Scheme 9) [29]. The use of propargyl alcohol and propargyl thiol led, via the acetylenic oximes, to fused tetrahydrofuranoisoxazoles 62 a and 62 b, and tetrahydrothiopheno[3,4-c]isoxa-zole 62 c, respectively. Reaction of l-butyn-4-ol with 0-trimethylsilyl a-bro-moaldoxime 52e (R = R = Me) led to the tetrahydropyranoisoxazole 62 d. 

Although the unsaturated nitrile oxides 124 can be prepared via the aldoxime route (see Scheme 8), the older procedure suffers from the disadvantage that a tenfold excess of allyl alcohol and two additional steps are required when compared to Scheme 15. Therefore, unsaturated nitro ether 123 that can be prepared by condensation of an aldehyde 120 and a nitro alkane followed by Michael addition of alcohol 122, was a useful precursor to nitrile oxide 124 [381. The nitrile oxide 124 spontaneously cyclized to ether 125. This procedure is particularly suitable for the synthesis of tetrahydrofurans (125a-h) and tetrahydropyrans (125i-k) possessing Ar substituents in 72-95% yield (Table 12). The seven-membered ether 1251 was obtained only in 30% yield on high dilution. The acetylenic nitro ether 126 underwent INOC reaction to provide the isoxazole 127. 

Violent reactions have occurred between ozone and many chemicals, a small selection being acetylene, alkenes, dialkyl zincs, benzene/rubber solution, bromine, carbon monoxide and ethylene, diethyl ether, hydrogen bromide, and nitrogen oxide. 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 46, 71 Sodio-2-formyl-6-methylcyclohexanone, 48,41... 

Macrocyclization,3 A new route to cembranolides (3) involves intramolecular coupling of an alkoxyallyltin derivative (1) with an acetylenic aldehyde catalyzed by BF30(C2H5)2 (cf. 12, 513-514). Thus in the presence of BF3 etherate 1 cyclizes to 2 with syn-selectivity. The product is converted to the cembranolide 3 by hydrolysis of the enol ether and oxidation. 

Adsorption of a specific probe molecule on a catalyst induces changes in the vibrational spectra of surface groups and the adsorbed molecules used to characterize the nature and strength of the basic sites. The analysis of IR spectra of surface species formed by adsorption of probe molecules (e.g., CO, CO2, SO2, pyrrole, chloroform, acetonitrile, alcohols, thiols, boric acid trimethyl ether, acetylenes, ammonia, and pyridine) was reviewed critically by Lavalley (50), who concluded that there is no universally suitable probe molecule for the characterization of basic sites. This limitation results because most of the probe molecules interact with surface sites to form strongly bound complexes, which can cause irreversible changes of the surface. In this section, we review work with some of the probe molecules that are commonly used for characterizing alkaline earth metal oxides. 

Moureu investigated the addition of alcohols, catalyzed by sodium methoxide, to acetylenic esters and has shown that enol ethers are formed as primary adducts. It has been shown that compounds such as potassium cyanide, a mixture of mercuric oxide, boron trifluoride,... 

As with alkenes we consider first those oxidations which do not cleave the acetylenic bond giving a-diketones, or oxidation of alkynyl amines and ethers to a-keto amides and esters, and then consider oxidative alkyne cleavage to acids. 

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