Sodium acetate, dehydration

Acetic anhydride/sodium acetate dehydrating agent, 86, 87, 89 isomaleimide rearrangement catalyst, 89, 90 Acetic anhydride/tertiary amines, dehydrating agent, 86, 89... 

Bisa.codyl, 4,4 -(2-PyridyLmethylene)bisphenol diacetate [603-50-9] (Dulcolax) (9) is a white to off-white crystalline powder ia which particles of 50 p.m dia predominate. It is very soluble ia water, freely soluble ia chloroform and alcohol, soluble ia methanol and ben2ene, and slightly soluble ia diethyl ether. Bisacodyl may be prepared from 2-pyridine-carboxaldehyde by condensation with phenol and the aid of a dehydrant such as sulfuric acid. The resulting 4,4 -(pyridyLmethylene)diphenol is esterified by treatment with acetic anhydride and anhydrous sodium acetate. Crystallisation is from ethanol. 

Condensation of an appropriately substituted phenylacetic acid with phthalic anhydride in the presence of sodium acetate leads to aldol-like reaction of the methylene group on the acid with the carbonyl on the anhydride. Dehydration followed by decarboxylation of the intermediate affords the methylenephthal-ides (12). Treatment of the phthalides with base affords directly the indandiones, probably via an intermediate formally derived from the keto-acid anion (13). The first agent of this class to be introduced was phenindandione (14) this was followed by anisindandione (1S) and chlorindandione (16). ... 

Benzyl acetate was prepared by addition of benzyl chloride (containing 0.6% pyridine as stabiliser) to preformed sodium acetate at 70°, followed by heating at 115°, then finally up to 135°C to complete the reaction. On one occasion, gas began to be evolved at the end of the dehydration phase, and the reaction accelerated to a violent explosion, rupturing the 25 mm thick cast iron vessel. This was attributed to presence of insufficient pyridine to maintain basicity, dissolution of iron by the... 

Phenylcinnamic acid has been prepared previously by a variety of methods, the best of which appear to be the dehydration of ethyl j3-hydroxy-/3,(3-diphenylpropionate by treatment with sodium acetate in acetic acid6 and the reaction of 1,1-diphenylethylene with oxalyl chloride.7... 

Phenyl cinnamate and other phenolic esters have been prepared by heating the acid and phenol in the presence of phosphorus oxychloride,1 and by heating the acid anhydride and phenol together in the presence of a dehydrating agent such as fused zinc chloride or anhydrous sodium acetate.2 Phenyl cinnamate has also been prepared by the careful distillation of phenyl fumarate.3... 

The glyoxime dehydration route is compatible with various substituents including not only alkyl, aryl, and heteroaryl but also acyl, carboxyl, and amino groups for example, 3-amino-4-phenylfurazan is formed on heating a-(hydroxyimino)phenylacetamidoxime with sodium acetate in ethanol, and the same compound also results from treatment of benzoyl cyanide with hydroxylamine and sodium acetate in ethanol <87IJC(B)690>. 

Sodium acetate is a mordant in dyeing. Other applications are in photography, as an additive to food, in purification of glucose, in preservation of meat, in tanning, and as a dehydrating agent. In analytical chemistry it is used to prepare buffer solution. 

Formylfuran behaves in a very similar manner to benzaldehyde and undergoes the usual reactions of an aromatic aldehyde, e.g. (i) the Cannizzaro reaction with cone, sodium hydroxide to give furan-2-ylmethanol and the sodium salt of furoic acid, (ii) the Perkin reaction with acetic anhydride and sodium acetate to yield an aldol product that dehydrates to 3-(furan-2-yl)propenoic acid, and (iii) a condensation with potassium cyanide in alcoholic solution to form furoin (under these conditions, benzaldehyde undergoes the benzoin condensation) (Scheme 6.32). 

It is well documented that the isoimide is the kinetically favoured product and that isomerization yields the thermodynamically stable imide when sodium acetate is used as the catalyst. High catalyst concentrations provide maleimides with low isoimide impurity. The mechanism by which the chemical imidization is thought to occur is shown in Fig. 3. The first step in the dehydration reaction may be formation of the acetic acid-maleamic acid mixed anhydride. This species could lose acetic acid in one of the two ways. Path A involves participation by the neighboring amide carbonyl oxygen to eject acetate ion with simultaneous or subsequent loss of proton on nitrogen to form the isoimide. Path B involves loss of acetate ion assisted by the attack of nitrogen with simultaneous or subsequent loss of the proton on nitrogen to form the imide. If the cyclodehydration is run in acetic anhydride in the absence of the base catalyst, isoimide is the main reaction product. 

Recently, benzo[c]furan has been of value in the synthesis of anthra-cyclinones. As Kende et found, 4, generated from the precursor 23, reacts with the quinone 75 (diglyme, 140 C) to give 76 and 77 in a total yield of 96% (ratio 3 1) dehydration of the mixture with acetic acid/sodium acetate (reflux, 16 hr) gives the desired product (78, 70%). Similar reaction sequences have been conducted with other benzo- and naphthoquinones. ... 

Benzofuran-3(2/f)-ones (396) exist in the keto form but undergo ready enolization. Acetylation with acetic anhydride and sodium acetate affords 3-acetoxybenzo[6]furans, but reaction under acidic conditions usually supplies these products admixed with 3-acetoxy-2-acetylbenzo[6]furans. Alkylation usually furnishes a mixture of O- and C-alkylated products. 3-Acetoxy-6-methoxy-4-methylbenzo[6]furan, on Vilsmeier reaction, supplies the 3-chlorobenzo[6]furan-2-carbaldehyde, the product expected from an enolizable ketone (72AJC545). Benzofuran-3(2//)-ones react normally with carbonyl reagents. Grignard reagents react in the expected way and dehydration of the intermediate affords a 3-substituted benzo[6]furan. The methylene group is reactive so that self condensation, condensation with aldehydes and ketones and reaction with Michael acceptors all occur readily. 

As is mentioned in the introductory material, chromium exhibits a propensity to form quadruple bonds that is unmatched by any other first-row transition metaL Although Cr2(02 CQl3)4(H20)2 was first reported over 100 years ago (210), it was not promoted as a quad ruple-bond-containing unit until Cotton and co-workers carried out a redetermination of the x-ray structure and reported a change in the chromium atom separation from the accepted value of 2.64 A initially reported in 1953 (251) to 2.3855(5) A (66, 67). Reduction of chromium trichloride to chromium(II) in aqueous solution with zinc followed by addition of sodium acetate is a convenient route to Cr2(02CCH3)4(H20)2 (204), which can be dehydrated by heating under vacuum to form Cr2(02 CCH3)4. 

Reaction XXIV. Condensation of certain Carbonyl Compounds with one another under the influence of Dehydrating Agents. (A., 223, 139.)— Aldehydes and ketones readily condense with one another under the influence of such reagents as zinc chloride, hydrochloric acid, sulphuric acid, alkali hydroxides, sodium acetate solution, etc., to give a/J-olefinic aldehydes and ketones ... 

Esterification is effected in the cold in presence of alkali or by heating the alcohol and anhydride together, usually in presence of a dehydrating agent—e.g., fused zinc chloride, anhydrous sodium acetate, etc. Preparation 204.—Mannitol Hexacetate. 

When an acid anhydride is used the reaction is usually carried out by the application of heat, and may be hastened by the addition of dehydrating agents, e.g., fused sodium acetate or fused zinc chloride. 

This method is mainly restricted to the synthesis of amino acids with aromatic side-chains since the required unsaturated azlactones [e.g. (30)] are most readily prepared using aromatic aldehydes. Typically, benzaldehyde condenses under the influence of base with the reactive methylene group in the azlactone (29) which is formed by the dehydration of benzoylglycine (28) when the latter is heated with acetic anhydride in the presence of sodium acetate (cf. Expt 8.21). The azlactone ring is readily cleaved hydrolytically and compounds of the type (30) yield substituted acylaminoacrylic acids [e.g. (31)] on boiling with water. Reduction and further hydrolysis yields the amino acid [e.g. phenylalanine,... 

The analysis depicted for (64) reveals that the synthesis of benzofuran involves the conversion of salicylaldehyde into the corresponding aryloxyacetic acid by reaction with sodium chloroacetate in the presence of alkali, followed by heating with a mixture of acetic anhydride, acetic acid and sodium acetate (Expt 8.24). The ensuing cyclisation may be regarded as an internal Perkin reaction (Section 6.12.3, p. 1036) accompanied by a decarboxylative dehydration step. 

The last compound was prepared as follows the hydroxyl groups of 3,4-dihydroxy-benzaldehyde was protected using t-butyldimethylsilylchloride (1). 100 mg (0.26 mmol) of 3,4-di(t-butyl-methylsiloxy)benzaldehyde was dissolved in 1 ml tetrahydrofurane under atmosphere of argon at -40°C, and 0.30 ml of metal complex from (S)-6,6 -bis(triethylsilylethynyl)-l,l-dihydroxy-2,2 -binaphtalene (2) mixed with a solution of n-butyllitium in hexane.After stirring for 30 minutes, 79.4 mg (1.3 mmol) of nitromethane was added dropwise to the mixture. After 67 hour reaction time, 2 ml of 1 N aqueous solution of hydrochloric acid added to stop the reaction. Product was extracted with 50 ml ethyl acetate, dehydrated with anhydrous sodium sulfate and concentrated within evaporator followed by silica gel chromatography (n-hexane/acetone = 10/1), after which (R)-l-(3,4-di(t-butyldimethylsiloxy) phenyl)-2-nitroethanol with an optical purity of 92% e.e. was obtained in a yield of 93%. 

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