Acetals alkaline conditions

Citral readily forms acetals by acid-catalyzed addition of alcohols or by the use of trialkoxyorthoformates. Citral dimethyl acetal [7549-37-3] is stable under alkaline conditions, whereas citral is not. Neryl and geranyl nitriles can be made by oximation of citral and dehydration of the intermediate oxime. For instance, geranonitrile [31983-27-4] is made as follows ... 

Reaction with Water. The alkyl carbonate esters, especially the lower ones, hydroly2e very slowly in water when compared to the carbonochloridic esters (chloroformates). Under alkaline conditions, the rates of hydrolysis are similar to those of the corresponding acetic acid esters. 

Benzal chloride is hydrolyzed to benzaldehyde under both acid and alkaline conditions. Typical conditions include reaction with steam in the presence of ferric chloride or a zinc phosphate catalyst (22) and reaction at 100°C with water containing an organic amine (23). Cinnamic acid in low yield is formed by heating benzal chloride and potassium acetate with an amine as catalyst (24). 

EDA reacts with formaldehyde and sodium cyanide under the appropriate alkaline conditions to yield the tetrasodium salt of ethylenediaminetetraacetic acid (24). By-product ammonia is removed at elevated temperatures under a partial vacuum. The free acid or its mono-, di-, or trisodium salts can be produced by the appropriate neutrali2ation using a strong mineral acid. This same reaction with other amines is used to produce polyamino acetic acids and their salts. These products are used widely as chelating agents. 

Acetates, benzoates, and cyclic carbonates are stable to these hydrolysis conditions. [Cyclic carbonates are cleaved by more alkaline conditions (e.., dil. NaOH, 20°, 5 min, or aq. Pyr, warm, 15 min, 100% yield).] ... 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

This has the same stiffness as dry nylon but absorbs less than one-fifth the amount of water and retains its strength and shape in humid conditions at considerably higher temperatures. Acetal has poor resistance to aqueous solutions of strong acids and should not be used at a pH below 3. The acetal s copolymers are satisfactory in most alkaline conditions. All grades have very good resistance to mineral oils and petrols and to most organic solvents including chlorinated compounds. 

The nitrate group is stable to the dilute alkaline conditions required for saponification of secondary acetates although it is cleaved during Wolff-Kishner reduction.Nitrates are stable to chromic acid oxidation in acetic acid, to organic peracids, and to lead tetraacetate.This group is readily split by reduction with zinc in acetic acid. 

Oxidation of 3-hydroxyfurazan-4-acetic acid with potassium permanganate under alkaline conditions gave 3-hydroxy-4-furazancarboxylic acid (1895CB753). The acid yielded an ester when heated in ethanol saturated with dry HCl. The ester... 

Compared with the alkaline conditions used in the above methods, the removal of the triethylstannylic group (triethyltin) occurs for 3(5)-triethylstannylethynylpyra-zole at room temperature in CCI4 solution in the presence of acetic acid (71ZOB 2230) (Scheme 99). 

Dinitroquinoline derivative 94 under alkaline conditions condensed to give tri-azolo[4,5-c]quinoline oxide 95. On the other hand, heating 94 in aqueous acetic acid is reported to provide 50% yield of 96 (Scheme 15) (80M963). 

Wood has a good resistance to a wide range of chemicals. The acid resistance is superior to that of most common metals. Iron begins to corrode at pH 5, whereas attack on wood commences at pH 2, and even at lower values proceeds at a very low rate. Wood has excellent resistance to acetic acid which is particularly destructive to most common metals. In alkaline conditions wood has good resistance up to pH 11. 

The purity and stability of three dichlorotriazine dyes applied in nonlinear optical materials was checked by RP-HPLC. The chemical structures of the dyes are shown in Fig. 3.131. Analyses were realized in an ODS column (250 X 4.6 mm i.d. particle size 5 jtim) using gradient elution. Aqueous ammonium acetate (50 mM) and methanol were solvents A and B, respectively. The detection wavelength depended on the absorption maxima of the dye. Chromatograms illustrating the decomposition of dyes under alkaline conditions are depicted in Fig. 3.132. It was established that the application of RP-F1PLC for the study of the purity and stability of dyes may facilitate their use in nonlinear optical materials. [179],... 

Reduction of substituted nitrobenzenes under alkaline conditions, usually with aqueous sodium acetate as electrolyte and a nickel cathode, is the classical method due to Elbs [45] for the formation of azo- and azoxy-compounds. Protons are used in the electrochemical reaction so that the catholyte becomes alkaline and under these conditions, phenylhydroxylamine reacts rapidly with nitrosobenzene to form azoxybenzene. Finely divided copper has long been known to catalyse the reduction of nitrobenzene to aniline in alkaline solution at the expense of azoxybenzene production [46]. Modem work confirms that whereas reduction of nitrobenzene at polycrystalline copper in alkaline solution gives mainly azoxybenzene, if the electrode is pre-oxidised in alkaline solution and then reduced just prior to the addition of nitrobenzene, high yields of aniline are obtained with good current efficiency... 

The alkylation of 5-(4-hydroxyphenoxy)-l/f-l,2,3-triazoles (147) under alkaline conditions exclusively yields the isomeric N(2) and N(3) alkylation products (148) and (149) (Equation (9)). For R = PhCH2, the N(2) and N(3) isomers are obtained in almost equal amounts, but for R = PhjC, only 1% of the N(3) isomer is formed because of steric hindrance. No N(l) alkylation is observed. Acylation and sulfonation of (147) under similar conditions results in attack at the phenolic oxygen <82JHCl 147>. Reaction of benzotriazole with 2-chlorothiophen-3-ones (150) in acetic acid gives 5-(benzotriazol-l-yl)-3-hydroxythiophene-2-carboxylates (151) (Equation (10)) <87JHC1301>. 

For all practical purposes, monomeric vinyl alcohol exists only in its tautomeric form as acetaldehyde. Therefore, poly(vinyl alcohol) (PVAlc) is prepared by the hydrolysis of polymers of vinyl esters. For practical reasons, the starting material of choice is poly(vinyl acetate) (PVAc). Although hydrolysis may be carried out under acidic conditions, alkaline conditions in the presence of an alcohol are preferred. The reaction may be represented by... 

For efficient extraction of macrolide and lincosamide residues from edible animal products, bound residues should be rendered soluble, most if not all of the proteins should be removed, and high recoveries for all analytes should be provided. Since tliese antibiotics do not strongly bind to proteins, many effective extraction methods have been reported. Sample extraction/deproteinization is usually accomplished by vortexing liquid samples or homogenizing semisolid samples with acetonitrile (136—139), acidified (136,140-142) orbasified acetonitrile (143), methanol (14, 144, 145), acidified (145-147) or basified methanol (148), chloroform (149-151), or dichloromethane under alkaline conditions (152). However, for extraction of sedecamycin, a neutral macrolide antibiotic, from swine tissues, use of ethyl acetate at acidic conditions has been suggested (153), while for lincomycin analysis in fish tissues, acidic buffer extraction followed by sodium tungstate deproteinization has been proposed (154). 

From the other anticoccidial drugs, benzamides can be readily extracted as ion-pairs into dichloromethane at strong alkaline conditions (pH 11) using tetrabutylammonium as pairing ion (257). Imidocarb residues have been partitioned into chloroform from alkaline water extracts containing sodium chloride (409), while ethopabate can be partitioned into ethyl acetate from water extracts containing sodium chloride widiout pH adjustment (388). 

Liquid-liquid partitioning cleanup is generally carried out at alkaline conditions using ethyl acetate (481, 484), ethyl acetate/tert.-butanol mixture (482), diethyl ether (478), or tert.-butylmethyl ether/n-butanol (485) as extraction solvents. The organic extracts are then either concentrated to dryness (482), or repartitioned with dilute acid to facilitate back-extraction of the analytes into the acidic solution. A literature survey shows that liquid-liquid partitioning cleanup resulted in good recoveries of substituted anilines such as clenbuterol (478, 481, 484), but it was less effective for more polar compounds such as salbutamol (482). 

Activated positions (e.g., ZCH2Z compounds) can be nitrated by fuming nitric acid in acetic acid, by acetyl nitrate and an acid catalyst,264 or by alkyl nitrates under alkaline conditions.265 In the latter case it is the carbanionic form of the substrate that is actually nitrated. What is isolated under these alkaline conditions is the conjugate base of the nitro... 

Acetal is stable under neutral or si alkaline conditions, but hydrolyzes in the presence of acids to form acetaldehyde... 

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