Double acetalization

The double acetate is prepared in the same general way as the double chloride but by dissolving one molecule of copper acetate with three molecules of calcium acetate. 

Double carbonate, double sulfate or double acetate has been used to separate and recover actinide so far (7, 8). However,high concentrations of carbonate, sulfate or acetate are necessary for their effective precipitation. On the other hand, relatively low concentrations of sulfate or carbonate are sufficient for the precipitation of actinide in the present method. Therefore, it is favorable for treatment of waste solution after separation and recovery of actinide. 

The open-chain form of glucose is in equilibrium with both pyranose and furanose forms by hemiacetal formation with the black and green OH groups, respectively. Normally, the pyranose form is preferred, but the furanose form can form a double acetal with acetone, one acetal having as-fused 5/5 rings and the other being on the side chain. This is the product. 

As for compound IV, it might be derived from cummuleno aldehyde XX, which in turn would be produced from the first acetate migration that gave XVII (Step K of Scheme 54.6). Thus, the presence of IV provides additional support to the double acetate shift mechanism (see Scheme 54.8). 

Double acetates of the composition M [M(OAc)4],xAc20 (M = Li, Na, K, NH4, or T1 M = Zn, Cd, or Hg x = 4,6) have been prepared, and possible structures are proposed. Electrical conductivity studies on molten zinc carboxylates of even-numbered chain length from to are consistent with a small concentration of relatively mobile Zn ions. ... 

Arabinose (as a j3-pyraiiose) I orms a double acetal (Section 24-8). So does ribo.se, bceau.sc in its o-pyrano.se form all four hydroxy groups are cis. 

Spinel ferrites have been prepared by thermal decomposition of crystallised pyridinates Me3Fe6(CH3C00)i7030H - I2C5H5N, with Me = Mg, Mn, Co and Ni (Wickham, Whipple Larson, 1960). Pyridinate crystals were prepared by dissolution of the basic double acetate, Ni4Fe9(CH3C02)26(OH)9 in hot pyridine, and then precipitated... 

With dialdehydes as enol components, the aldol reaction may be followed by an acetalization event Thus, Hayashi and coworkers [10] established a highly enan-tioselective proHne-catalyzed domino aldol-acetalization of aqueous tetrahydro-2H-pyran-2,6-diol (21) and aldehydes (Scheme 8.7). In this sequence, the intermediate aldolate product 22 is trapped by the additional aldehyde moiety to generate a lactol, which through addition of methanol and acid is converted into the double acetal 23. 

Pashley R M, McGuiggan P M, Ninham B W, Brady J and Evans D F 1986 Direct measurements of surface forces between bilayers of double-chained quaternary ammonium acetate and bromide surfactants J. Phys. Chem. 90 1637-42... 

Into a 1 litre round-bottomed flask, fitted with a double surface condenser, place 250 g. (277 ml.) of dry ethyl acetate (1) and 25 g. of clean sodium wire (2). Warm the flask on a water bath in order to start the reaction. Once the reaction commences, it proceeds vigorously and cooling of the flask may be necessary in order to avoid loss of ethyl... 

The formation of ethyl isopropylidene cyanoacetate is an example of the Knoevenagel reaction (see Discussion before Section IV,123). With higher ketones a mixture of ammonium acetate and acetic acid is an effective catalyst the water formed is removed by azeotropic distillation with benzene. The essential step in the reaction with aqueous potassium cyanide is the addition of the cyanide ion to the p-end of the ap-double bond ... 

The addition of active methylene compounds (ethyl malonate, ethyl aoeto-acetate, ethyl plienylacetate, nltromethane, acrylonitrile, etc.) to the aP-double bond of a conjugated unsaturated ketone, ester or nitrile In the presence of a basic catalyst (sodium ethoxide, piperidine, diethylamiiie, etc.) is known as the Michael reaction or Michael addition. The reaction may be illustrated by the addition of ethyl malonate to ethyl fumarate in the presence of sodium ethoxide hydrolysis and decarboxylation of the addendum (ethyl propane-1 1 2 3-tetracarboxylate) yields trlcarballylic acid ... 

Ethyl phenylethylmalonate. In a dry 500 ml. round-bottomed flask, fitted with a reflux condenser and guard tube, prepare a solution of sodium ethoxide from 7 0 g. of clean sodium and 150 ml. of super dry ethyl alcohol in the usual manner add 1 5 ml. of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60° and maintain this temperature for 30 minutes. Meanwhile equip a 1 litre threenecked flask with a dropping funnel, a mercury-sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g. of ethyl phenylmalonate and 60 g. of ethyl iodide in the flask. Heat the apparatus in a bath at 80° and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indieator is never more than faintly pink. The addition occupies 2-2 -5 hoius continue the stirring for a fiuther 1 hour at 80°. Allow the flask to cool, equip it for distillation under reduced pressure (water pump) and distil off the alcohol. Add 100 ml. of water to the residue in the flask and extract the ester with three 100 ml. portions of benzene. Dry the combined extracts with anhydrous magnesium sulphate, distil off the benzene at atmospheric pressure and the residue under diminished pressure. C ollect the ethyl phenylethylmalonate at 159-160°/8 mm. The yield is 72 g. 

If one is absolutely serious about ultra pure safrole then it can be separated from the eugenol-free sassafras oil by treatment with mercuric acetate [1,2,3,4] which likes that terminal double bond that only safrole has. The Hg(AcO)2 latches on to safrole at that double bond bringing it into solution as a solid sort of like the way that eugenol was. The safrole can then be separated from its still oily buddies by vacuum filtration. Safrole is then regenerated to its normal oily form by treatment with hydrochloric acid (HCI) which flicks the Hg(AcO)2 off the safrole and the safrole double bond reforms. As it so happens, the mercuric acetate also reforms intact so that it can be reused again such as in one of those... 

It has been shown that by doubling the amount of nitroethane respective to that of the aldehyde in a ratio of 2 to 1, then the amount of ammonium acetate used can be reduced considerably [28 p703J. 

Selective reduction of a benzene ring (W. Grimme, 1970) or a C C double bond (J.E. Cole, 1962) in the presence of protected carbonyl groups (acetals or enol ethers) has been achieved by Birch reduction. Selective reduction of the C—C double bond of an a,ft-unsaturated ketone in the presence of a benzene ring is also possible in aprotic solution, because the benzene ring is redueed only very slowly in the absence of a proton donor (D. Caine, 1976). 

Cyclopropane rings are opened hydrogenolytically, e.g., over platinum on platinum dioxide (Adam s catalyst) in acetic acid at 2 - 4 bars hydrogen pressure. The bond, which is best accessible to the catalyst and most activated by conjugated substituents, is cleaved selectively (W.J. Irwin, 1968 R.L. Augustine, 1976). Synthetically this reaction is useful as a means to hydromethylate C—C double bonds via carbenoid addition (see p. 74f. Z. Majerski, 1968 C.W. Woodworth, 1968). 

C—C double bonds may be protected against electrophiles by epoxidation and subsequent removal of the oxygen atom by treatment with zinc and sodium iodide in acetic acid (J.A. Edwards, 1972 W. Kndll, 1975). Halogenation has often been used for protection, too. The C—C double bond is here also easily regenerated with zinc (see p. 138, D.H.R. Barton, 1976). 

The resulting macrocyclic ligand was then metallated with nickel(II) acetate. Hydride abstraction by the strongly electrophilic trityl cation and proton elimination resulted in the formation of carbon-carbon double bonds (T.J. Truex, 1972). 

The oxidation of the cyclic enol ether 93 in MeOH affords the methyl ester 95 by hydrolysis of the ketene acetal 94 formed initially by regioselective attack of the methoxy group at the anomeric carbon, rather than the a-alkoxy ketone[35]. Similarly, the double bond of the furan part in khellin (96) is converted ino the ester 98 via the ketene acetal 97[l23],... 

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