By the Schotten-Baumann procedure

Oxazolin-5-ones have also proven to be important intermediates in the homologation of carboxylic acids (71AG(E)655). The IV-acyl-DL-valine derivative (402), prepared from the acid chloride of the carboxylic acid and DL-valine by the Schotten-Baumann procedure, was treated with excess acetic anhydride to afford (403). Reaction of (403) with acrylonitrile and triethylamine led to (404) in good yield. Hydrolysis of (404) with dilute alkali or acid gave the y-keto nitrile or y-keto acid (Scheme 89). 

The benzanilide should be of good quality, or tarry material will form and interfere with purification of the product. Benzanilide is readily made by the Schotten-Baumann procedure from aniline, 10% aqueous sodium hydroxide, and benzoyl chloride in the proportions 6 30 5, and after crystallization from 95% ethanol is sufficiently pure. 

Helferich found that phenols can be mesylated, either in pyridine or by the Schotten-Baumann procedure, and found that the mesylates are extraordinarily... 

In a procedure for Ihc preparation of their diazomethane precursor, p-tolyl-siiifunyimethylnitrosamidc. de Boer and Backer carried out the reaction of tosyi chloride with methylaminc by the Schotten-Baumann procedure, that is with the alternating adiitlen of acid chloride and sodium hydroxide solution. 

Aryl arenesulfonates mostly crystallize readily and are useful for identification of phenols or sulfonic acids they are easily obtained from the acid chlorides and phenols in the presence of alkali689 or a tertiary base690 by the Schotten-Baumann procedure. 

Sulfinyl chlorides, analogously to sulfonyl chlorides, are important starting materials for the preparation of other sulfinic acid derivatives. Thus, when warmed with alcohols they give sulfinic esters,712 713 and esterification can also be carried out by the Schotten-Baumann procedure in the presence of pyridine or potassium carbonate.714... 

The acid chlorides are generally more reactive than the corresponding acid anhydrides. In fact, the alcoholysis of acid chlorides is probably the best laboratory method for preparing esters. Frequentiy, basic materials are added during the course of the reaction to neutralize by-product hydrochloric acid. When the basic material is aqueous caustic, the procedure is referred to as the Schotten-Baumann procedure (73). Esterification of tertiary alcohols by acid chlorides is described in Reference 74. Esters of tertiary alcohols can also be formed through an intermediate /-butyl thioate group (75) ... 

The choice of which reactions to include is not an easy one. First there are the well known "Name Reactions", that have appeared in various monographs or in the old Merck index. Some of these are so obvious mechanistically to the modern organic chemistry practitioner that we have in fact omitted them for instance esterification of alcohols with acid chlorides - the Schotten-Baumann procedure. Others are so important and so well entrenched by name, like the Baeyer-Villiger ketone oxidation, that it is impossible to ignore them. In general we have kept older name reactions that are not obvious at first glance. 

The reaction between acyl halides and alcohols or phenols is the best general method for the preparation of carboxylic esters. It is believed to proceed by a 8 2 mechanism. As with 10-8, the mechanism can be S l or tetrahedral. Pyridine catalyzes the reaction by the nucleophilic catalysis route (see 10-9). The reaction is of wide scope, and many functional groups do not interfere. A base is frequently added to combine with the HX formed. When aqueous alkali is used, this is called the Schotten-Baumann procedure, but pyridine is also frequently used. Both R and R may be primary, secondary, or tertiary alkyl or aryl. Enolic esters can also be prepared by this method, though C-acylation competes in these cases. In difficult cases, especially with hindered acids or tertiary R, the alkoxide can be used instead of the alcohol. Activated alumina has also been used as a catalyst, for tertiary R. Thallium salts of phenols give very high yields of phenolic esters. Phase-transfer catalysis has been used for hindered phenols. Zinc has been used to couple... 

Because the reaction of an amine with an acyl chloride is much faster than the hydrolysis of the acyl chloride, the reaction can usually be carried out in an aqueous alkali solution. This is well known as the Schotten-Baumann procedure.6 For example, a number of N-acyl taxol analogs have been prepared under Schotten-Baumann conditions by the reaction of A-debenzoyltaxol with various acid chlorides (Eq. 9.4).7 Highly purified /V-long-chain-acyl neutral amino acids such as potassium AMauroyTy-aminobutyrate, useful as surfactants for detergent... 

As in the preparation of polyesters, also in the preparation of polyamides, the reaction temperature can be considerably reduced by using derivatives of dicarbo-xylic acids instead of the free acids. Especially advantageous in this connection are the dicarboxylic acid chlorides which react with diamines at room temperature by the Schotten-Baumann reaction this polycondensation can be carried out in solution as well as by a special procedure known as interfacial polycondensation (see Examples 4-11 and 4-12). 

Another interesting example of resolution through formation of diastereo-mers is the isolation of four stereoisomers of 3-amino-2-methyl-3-trifluoro-methyl butanoic acid [55]. In this process, the chemical-enzymatic method by the combination of chemical and enzymatic reaction is a very convenient. At first, -phenylacetyl derivatives 61a and 61b were prepared in excellent isolated yields via the Schotten-Baumann procedure. After these materials were hydrolysed with penicillin acylase (EC 3.5.1.11) from Escherichia coli until attainment of 50% conversion, enzymatically unconverted -phenylacetyl derivatives 62 a and 62 b (organic layer) and amino acids 63 b and 63 d (aqueous layer) were separated. Acidic hydrolysis of unconverted materials produced other stereoisomers 63 a and 63 c in high optical pure form. 

A simultaneous way of determining ammonia including aliphatic amines, aromatic amines, and phenols in environmental samples by GC-MS method using a single derivatization reagent has been reported recently by Mishra et al. The method consisted in precolumn formation of benzoate esters and benzamides under the conditions of the Schotten-Baumann procedure with benzoyl chloride and SPE of the derivatives. The limit of detection of ammonia was 20 /rg/l when 80 ml of sample was preconcentrated, after derivatization, on a styrene divinyl benzene copolymer sorbent. 

The acyl derivatives are formed very easily (usually by reaction of the amine with the acyl chloride or anhydride, employing the Schotten-Baumann procedure ) and a good number of them have been used to protect various amines. While all of them can be removed with varying degrees of ease, using acidic or basic hydrolysis, some protecting groups can be removed by other means such as oxidation (formyl, phlorethyl), reduction (formyl, dibenzylphosphonyl) or electrolysis (phloretyl, benzoyl). 

The polyamides were first prepared, by a low temperature interfacial condensation procedure using optically active diacid chloride with the appropriate diamine by the Schotten-Baumann reaction [52] which is often accompanied by various side reactions and introduces particularly 5-keto-amide groups, thereby decreasing the regularity of the polymer following Scheme XXII. 

In order to prepare benzoyl derivatives and substituted benzoyl derivatives on semimicro and micro scales, a cold suspension of an alkaline (5% NaOH) amine solution is shaken with a 2 — 3 fold excess of the chloride dissolved in a minimum amount of benzene. The derivative is isolated by evaporating the benzene. If this procedure is unsuccessful, the reaction is carried out by heating the components in pyridine. If the micropreparation is carried out by the Schotten-Baumann method, the reaction mixture should be neutralized after the reaction has stopped, in order to completely separate the benzoyl derivative of the type RCONHR. In view of the presence of a hydrogen atom on the nitrogen, the latter is partly soluble in the aqueous phase however, the pH of the solution should not drop below 8 (to prevent the precipitation of benzoic acid). 

For the introduction of the benzoyl group (benzoylation) the procedure generally adopted is to use benzoyl chloride in dilute (10 per cent) alkaline solutions. Since benzoyl chloride reacts slowly with water at room temperature, the amino compound reacts fairly rapidly when shaken with it. The hydrogen chloride produced in the acylation is removed by the alkali. This method is known as the Schotten-Baumann reaction. The benzoyl derivatives nearly always crystallize well. The product is recrystallized to remove adsorbed and occluded impurities. If the derivative does not crystallize well, then a substituted benzoyl chloride is used, for example, p-nitrobenzoyl chloride. It will be recalled that for the characterization of the alcohols use was made of 3, 5-dinitrobenzoyl chloride. 

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