Acetates, alkyl

Potassium acetate can be readily alkylated in a domestic microwave oven by use of equivalent amounts of salt and alkylating agent in the presence of Aliquat 336 (10 mol%). Some important results, exemplified by Eq. (1), are given in Tab. 5.1 [10, 11], 

Yields are always almost quantitative within 1-2 min, irrespective of chain length and the nature of the halide leaving groups. 

This procedure was scaled up from 50 mmol to the 2 mol scale (i.e. from 15.6 to 622.4 g total starting materials) in a larger batch reactor (Synthewave 1000) [12]. Yields were equivalent to those obtained under the original conditions (5 min, 160 °C) in the laboratory-scale experiment (Synthewave 402) (Tab. 5.2). 

Reactor Amounts of materials [g (mol)] Total amount (g) VieW (%) 

Xu et al. have obtained similar results with n-butyl bromide using TBAB (10 mol%) and alumina (4 1 ivjxv) as the catalyst [13]. Benzyl acetate was also conveniently prepared from sodium acetate and benzyl halide by use of microwave irradiation and PTC in synergy [14]. 

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Contaminants and by-products which are usually present in 2- and 4-aminophenol made by catalytic reduction can be reduced or even removed completely by a variety of procedures. These include treatment with 2-propanol (74), with aUphatic, cycloaUphatic, or aromatic ketones (75), with aromatic amines (76), with toluene or low mass alkyl acetates (77), or with phosphoric acid, hydroxyacetic acid, hydroxypropionic acid, or citric acid (78). In addition, purity may be enhanced by extraction with methylene chloride, chloroform (79), or nitrobenzene (80). 

More useful than the preceding methods is cleavage of alkoxides by acetyl chloride or bromide. One, two, three, or four alkoxyls can be replaced by chloride or bromide. Benzoyl chloride gives poor yields, however. The tri- and tetrachlorides, which are stronger Lewis acids than mono- and dichlorides, coordinate with the alkyl acetate formed and yield distillable complexes (46,55,56). 

In the slurry process, the hydrolysis is accompHshed using two stirred-tank reactors in series (266). Solutions of poly(vinyl acetate) and catalyst are continuously added to the first reactor, where 90% of the conversion occur, and then transferred to the second reactor to reach hiU conversion. Alkyl acetate and alcohols are continuously distilled off in order to drive the equiUbrium of the reaction. The resulting poly(vinyl alcohol) particles tend to be very fine, resulting in a dusty product. The process has been modified to yield a less dusty product through process changes (267,268) and the use of additives (269). Partially hydroly2ed products having a narrow hydrolysis distribution cannot be prepared by this method. 

TrimethylsiIy 1-5-alkyl Acetals and Ketals R2C(SR )OSiMe3 Formation... 

However, 17a,21-acetonides (103), as well as acetals of other ketones or aldehydes, can be easily prepared by acid-catalyzed exchange reaction with dimethoxypropane or other alkyl acetals in dimethylformamide or benzene. Enol etherification of the A -S-ketone also occurs with the former procedure. 

The following conditions selectively remove a phenolic acetate in the presence of a normal alkyl acetate ... 

Table 4), which indicates slower rates of hydrolysis of the alkyl acetates in the presence of the resin catalyst. 

From what alkyl bromide was the following alkyl acetate made by SN2 reac tion Write the reaction, showing all stereochemistry. 

The following reactivity order has been found for the saponification of alkyl acetates by aqueous NaOH. Explain. 

Organoboranes can also be used to construct carbon-carbon bonds by several other types of reactions that involve migration of a boron substituent to carbon. One such reaction involves a-halo carbonyl compounds.20 For example, ethyl bromoac-etate reacts with trialkylboranes in the presence of base to give alkylated acetic acid derivatives in excellent yield. The reaction is most efficiently carried out with a 9-BBN derivative. These reactions can also be effected with (3-alkenyl derivatives of 9-BBN to give (3,y-unsaturated esters.21... 

In order to produce free alkyl acetates, the alkoxyacetyl complexes 5-7 must first isomerize to carboalkoxymethyl compounds... 

The same results obtain whether carboalkoxy compounds 12,13 or alkoxyacetyl complexes 6,7 are treated with excess acid. Alkyl acetate liberated in these experiments, of course, derives from two CO ligands on CpFe(CO)3+ (1). 

In terms of economical synthetic approaches to indoles, the synthesis of this heterocycle from anilines and trialkylammonium chlorides was effected in an aqueous medium (H20-dioxane) at 180°C in the presence of a catalytic amount of ruthenium(III) chloride hydrate and triphenylphosphine together with tin(II)chloride <00TL1811>. Muchowski devised a novel synthetic route to indole-4-carboxaldehydes and 4-acetylindoles 86 via hydrolytic cleavage of W-alkyl-5-aminoisoquinolinium salts 85 to homophthaldehyde derivatives upon heating in a two phase alkyl acetate-water system containing an excess of a 2 1 sodium bisulfite-sodium sulfite mixture <00JHC1293>. 

As indicated in Scheme 3-13, replacing the isopropoxide counterions with less basic oxyanions, namely, commercially available 3,5-di-/< r/-butylsalicylic acid, will lead to new catalyst 30, which shows very good results for the asymmetric aldol addition of alkyl acetate to ketene acetals (Scheme 3-13). 

D-Glucono-1,5-lactone has been transformed (23) into trihydroxycarbox-ylates bearing a long-chain alkyl acetal group (15a,b). The synthesis involves the acetalation of HO-4 and HO-6 with a long-chain alkyl carbonyl com-... 

The acid-catalyzed acetalation of aldonolactones with alkyl acetals of aldehydes or ketones takes place, in some instances, with esterification of the lactone group to give acetal derivatives of alkyl aldonates (11,22). 

These observations do not, however, mean that TBT carboxylates and TBTCl are ionic in nature. After detailed analysis of the physical evidence such as the low specific conductance and dipole moment of trialkyltin halides, Neumann has concluded that they have no "salt-like constitution" (6). Bonding in the trialkyltin carboxylates also is essentially similar to that in covalent alkyl esters, as evidenced by the low dipole moment of 2.2D for tributyltin acetate in benzene, as compared to 1.9D for alkyl acetates (7). 

Saknrai, M., Nakamnra, K., and Nitta, K. Partial molar volnmes of alkyl acetates in water, J. Chem. Eng. Data, 41(5) 1171-1175, 1996. 

Vinyl ethers are important raw materials in the production of glutaraldehyde, as well as of vinyl polymer materials which contain oxygen and are expected to degrade easily in Nature. The [IrCl(cod)]2 catalyzes an efficient exchange reaction between vinyl acetate 57 and alcohols or phenols 58, leading to the corresponding vinyl ethers 59 (Equation 10.11) [27]. Usually, the acid-catalyzed exchange reaction between alcohols and vinyl acetate results in alkyl acetates 60, and also to vinyl alcohol 61 which is readily isomerized to acetaldehyde 62. 

Olivetol. (5-Alkyl Resourcinol) BER 69, 1644 (1936). Mix 25 g of ethyl-3,4,5-trimethoxy benzoyl acetate and 2.0 g of clean sodium in 100 ml ethanol and warm to react. Add 2 g n-propyl iodide (this may be replaced with n-amyl iodide) and heat on a steam bath for 12 hours, then neutralize and remove the ethanol by distillation. Extract the residue with ether, dry, and evaporate in vacuo to get 30 g of the alkyl acetate. Heat 22 g of this acetate in 5% KOH ethanolic solution for 1 hour at 50° and let stand to precipitate 14 g of 3,4,5-trimethoxyvalerophenone. Mix 11 g of the above product with 60 g of sodium in 600 ml ethanol. Warm and after dissolving the sodium add 2 liters of water. M e acidic with HCl acid and remove the ethanol by distillation. Extract with ether, dry, and evaporate the ether in vacuo to get if. g olivetol dimethyl ether. To demethylate this ether add it to 70 ml of hydrogen iodide and heat to boiling and reflux for two hours. Distill and keep the fraction at 160°-170° with 3-4 mm of vacuum applied to the distillation set-up. Yield about 6 g. 

Figure 2 illustrates the effect of incremental changes in ruthenium catalyst content upon the production of acetic acid and its C1--C2 alkyl acetate esters. Acetic acid production is maximized at Ru/Co ratios of ca. 1.0 1.5 however, the data in Figure 2 do show an approximate first order dependence of lOAc (acetic acid plus acetate esters) upon initial ruthenium content—at least up to the 2/1, Ru/Co stoichiometry under the chosen conditions. Selectivity to acetic acid in the liquid product peaks at 92 wt % (carbon efficiency 95 mol %) for a catalyst combination with initially low Ru/Co ratios (e.g. 1 4). The formation of C1-C2 alkanols and their acetate esters rapidly exceeds acetic acid productivity when the Ru/Co atomic ratio is raised above 1.5, although two-carbon oxygenates continue to be the predominant fraction. Smaller quantities of glycol may also be in evidence. 

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