Alcohols aldehydes, bisulfite

Analogously, aldehydes react with ammonia [7664-41-7] or primary amines to form Schiff bases. Subsequent reduction produces a new amine. The addition of hydrogen cyanide [74-90-8] sodium bisulfite [7631-90-5] amines, alcohols, or thiols to the carbonyl group usually requires the presence of a catalyst to assist in reaching the desired equilibrium product. 

Common impurities found in aldehydes are the corresponding alcohols, aldols and water from selfcondensation, and the corresponding acids formed by autoxidation. Acids can be removed by shaking with aqueous 10% sodium bicarbonate solution. The organic liquid is then washed with water. It is dried with anhydrous sodium sulfate or magnesium sulfate and then fractionally distilled. Water soluble aldehydes must be dissolved in a suitable solvent such as diethyl ether before being washed in this way. Further purification can be effected via the bisulfite derivative (see pp. 57 and 59) or the Schiff base formed with aniline or benzidine. Solid aldehydes can be dissolved in diethyl ether and purified as above. Alternatively, they can be steam distilled, then sublimed and crystallised from toluene or petroleum ether. 

Ketones are more stable to oxidation than aldehydes and can be purified from oxidisable impurities by refluxing with potassium permanganate until the colour persists, followed by shaking with sodium carbonate (to remove acidic impurities) and distilling. Traces of water can be removed with type 4A Linde molecular sieves. Ketones which are solids can be purified by crystallisation from alcohol, toluene, or petroleum ether, and are usually sufficiently volatile for sublimation in vacuum. Ketones can be further purified via their bisulfite, semicarbazone or oxime derivatives (vide supra). The bisulfite addition compounds are formed only by aldehydes and methyl ketones but they are readily hydrolysed in dilute acid or alkali. 

The material is triturated with saturated sodium bisulfite solution (2 cc. per gram), and after about three hours the pasty mixture is filtered with suction. The addition product is washed with absolute alcohol and then with ether and transferred to a flask fitted for steam distillation. Excess sodium carbonate solution is added and the aldehyde is distilled in a current of steam. 

Benzyl alcohol, 23, 14 BeNZYLAMINE, a-METHYL-, 23, 68 Benzyl carbamate, 23, 14 Benzyl chloride, 21, 99 Benzyl chloroeormate, 23, 13 Benzyl cyanide, 23, 71 Bisulfite compound, use for purification of an aldehyde, 23, 78 use for purification of a ketone, 23, 79 Blood, defibrinated, 21, 53 Booster pump, use of, for hydrogenation, 23, 69... 

Benzaldehyde. There are many ways to make many types of benzaldehydes. Different benzal-dehydes give different products. I am giving the formula to the basic type. It can be modified to give a specific type of benzaldehyde. 50 g of benzyl chloride and 50 g of copper nitrate in 300 cc of water are refluxed together, in a current of carbon dioxide for 8Vi hours or until a sample tested contains very little chlorine. Extract the mixture with ether, remove the ether on a water bath, and stir or shake the remaining oil for 1 hour (shaking is best) with a saturated solution of sodium bisulfite. Let stand for 2 hours, filter with vacuo and wash with a little cold alcohol, then with cold ether. The washings are warmed with an excess of 10% sulfuric acid. The aldehyde... 

Ethyl acetate is the major low-boiling impurity of heads fractions from continuous columns if bisulfites are absent in the distilling material. A heads fraction from a typical brandy column usually contains less than 1% of these volatile impurities, although the concentrated heads from an aldehyde-concentrating column may contain as much as 10-15% aldehydes. In either case, ethyl alcohol is the major component of the heads cut, and its recovery in usable form has been a troublesome processing problem. 

This is probably the single most important material used by the fragrance industry. Several million pounds are used annually, mainly in soaps and detergents. The principal method of manufacture shown in Figure 10 is by hydration of citronellal via the bisulfite addition product (2). The aldehyde moiety must be protected before hydration. A second manufacturing process starts with citronellol which is hydrated under acid conditions. The primary alcohol end of the molecule is then dehydrogenated catalytically or by oxidation to the aldehyde. 

Condensation of sodium salts of acinitroalkanes with the sodium bisulfite addition products of aldehydes in the presence of trace of alkali or weak acid also gives nitro alcohols as reported byKamlet o. 

As pointed out by Skrabal and Schiffrer [173], the rate-determining step must be in the transition from acetal to hemiacetal because the rate coefficient for the hydrolysis of methyl ethyl formal is equal to the mean value of those for the hydrolyses of dimethyl formal and diethyl formal. Wolf and Hero Id [174] supplied more direct evidence on this matter. They found that the UV absorption bands of aldehydes slowly decrease in alcoholic solutions. This indicates that a reaction takes place. The product of the reaction immediately splits off aldehyde under the conditions of a bisulfite titration, therefore it cannot be acetal and it must be hemiacetal. Acetals are much more stable, and they are not hydrolyzed in a bisulfite titration. A quantitative kinetic study of the reaction of aldehyde with alcohol was carried out by Lauder (175] with the aid of dilatometric and refractive index measurements. He observed that hemiacetal is formed in a relatively fast reaction which is followed by a slow reaction leading to acetal. 

The yields of nitro alcohols from simple nitroparaffins and aliphatic aldehydes or benzaldehyde are usually above 60%. The condensations are generally carried out with aqueous ethanolic sodium hydroxide, although weaker bases are sometimes desirable to prevent polymerization of the aldehyde. Sodium bisulfite addition compounds of the aldehydes are sometimes used. Better results are obtained with sodium methoxide than with alkali hydroxides in the condensation of nitroethane with formaldehyde. Sodium alkoxides are also used to effect the condensation of nitroethane with acetone and cyclohexanone. Condensation proceeds to the nitroalkanediol stage in certain cases with both nitromethane and with formaldehyde. ... 

The preparation of certain substituted benzils by treatment of aryl benzyl ketones with selenium dioxide is discussed later (method 183). If a methyl ketone is treated under these conditions, the methyl group is oxidized to an aldehyde group/ The reaction is carried out by refluxing a mixture of selenium dioxide and ketone in dioxane or alcohol for several hours. Preparative details are found in the procedures for phenylglyoxal (72%) and glyoxal (74%) the latter is isolated as its bisulfite derivative. 

It can thus be seen that zwitterions IV and V would be stabilized by the interaction of the alcohol with them, and the ozonide would have no opportunity to form and decompose abnormally. Whether zwitterions IV and V are formed in equal amounts depends upon the groups which are attached to the double bond and the carbon atom to which the ozone molecule initially adds. The final products, VI and VII, may be considered as hemiperacetals or hemiperketals and could be isolated only under special conditions. However, they can be easily decomposed with either sulfurous acid or sodium bisulfite and the ketones or aldehydes formed determined quantitatively as their 2,4-dinitrophenylhydrazones. 

When the ozonization of cinnamyl alcohol was carried out in methyl chloride at —70° C., followed by removal of the solvent at —10° and immediate reduction of the residue with sodium bisulfite and conversion of the aldehydes to their corresponding 2,4-dinitrophenyl-hydrazones, benzaldehyde and glycolic aldehyde were obtained in yields of 98 and 70%, respectively. No formaldehyde was detected. 

Aldehydes. Conversion to solid sodium bisulfite addition product with excess reagent, removal of nonaldehydic material by washing with alcohol or ether, and regeneration usually with acid, base, or sodium carbonate, provides a convenient method of purification. Examples syringic aldehyde, n-hexaldehyde. ... 

The best derivative from which an aldehyde can be recovered readily is its bisulfite addition compound, the main disadvantage being the lack of a sharp melting point. The aldehyde (sometimes in ethanol) is shaken with a cold saturated solution of sodium bisulfite until no more solid adduct separates. The adduct is filtered off, washed with a little water, followed by alcohol. A better reagent to use is a freshly prepared saturated aqueous sodium bisulfite solution to which 75% ethanol is added to near-saturation. (Water may have to be added dropwise to render this solution clear.) With this reagent the aldehyde need not be dissolved separately in alcohol and the adduct is finally washed with alcohol. The aldehyde is recovered by dissolving the adduct in the least volume of water and adding an equivalent quantity of sodium carbonate (not sodium hydroxide) or concentrated hydrochloric acid to react with the bisulfite, followed by steam distillation or solvent extraction. 

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