Schmidt reaction


The second reaction is favoured by sunlight and by catalysts such as platinum black or metallic oxides (cf. the decomposition of  [c.323]

By applying the BROAD classification feature to the hit list of the first example, described in Section 5.13.2, 18 clusters arc found, llic second reaction instance of the first cluster is shown in figure 5-30.  [c.268]

Figure 5-30. Second reaction instance of the first cluster for Example 1, obtained by applying the BROAD classification method, Figure 5-30. Second reaction instance of the first cluster for Example 1, obtained by applying the BROAD classification method,
Claisen-Schmidt reaction. Aromatic aldehydes condense with aliphatic or mixed alkyl-aryl ketones in the presence of aqueous alkali to form ap-unsaturated ketones  [c.709]

By catalytic reduction of a p-unsaturated ketones, prepared from aldehydes by the Claisen - Schmidt reaction (see under Aromatic Aldehydes), for example  [c.726]

VI,23. THE SCHMIDT REACTION OR REARRANGEMENT  [c.917]

The conversion of a carboxylic acid into an amine by treatment with hydrazoic acid in concentrated sulphuric acid is known as the Schmidt reaction or rearrangement  [c.917]

The Schmidt reaction (as applied to a carboxylic acid) is therefore a method for the degradation of an acid to an amine with one less carbon atom and in this respect resembles the Hofmann rearrangement (see discussion prior to Section 111,16) of acid amides. The yields are often higher and the carboxylic acid may be employed directly. The disadvantages are the toxicity of the reagent (usually a 4r-l() per cent, solution of hydrazoic acid in chloroform or benzene) thus necessitating rigorous precautions, and also the possibility of explosion during the  [c.917]

Knoevenagel reaction Knorr pyrrole synthesis. Kolbe>Schmitt reaction Leuckart reaction Mannich reaction  [c.1210]

Claisen-Schmidt reaction (Section  [c.783]

Ludwig Claisen was a Ger man chemist who worked during the last two decades of the nineteenth century and the first two decades of the twentieth His name is associated with three reac tions The Claisen-Schmidt reaction was presented in Section 18 10 the Claisen condensation is discussed in this section and the C/a/sen rearrangement will be intro duced in Section 24 13  [c.887]

CARBOXYLATION OF PHENOLS ASPIRIN AND THE KOLBE-SCHMITT REACTION  [c.1006]

The key compound m the synthesis of aspirin salicylic acid is prepared from phe nol by a process discovered m the nineteenth century by the German chemist Hermann Kolbe In the Kolbe synthesis also known as the Kolbe—Schmitt reaction, sodium phen oxide IS heated with carbon dioxide under pressure and the reaction mixture is subse quently acidified to yield salicylic acid  [c.1006]

Carboxylation of Phenols Aspirin and the Kolbe-Schmitt Reaction  [c.1007]

The Kolbe-Schmitt reaction is an equilibrium process governed by thermodynamic control The position of equilibrium favors formation of the weaker base (salicylate ion) at the expense of the stronger one (phenoxide ion) Thermodynamic control is also responsible for the pronounced bias toward ortho over para substitution Salicylate anion IS a weaker base than p hydroxybenzoate and predominates at equilibrium  [c.1007]

The Kolbe-Schmitt reaction has been applied to the preparation of other o hydroxy benzoic acids Alkyl derivatives of phenol behave very much like phenol itself  [c.1007]

Kolbe-Schmitt reaction (Section 24 10) The high pressure re action of the sodium salt of a phenol with carbon dioxide to give an o hydroxybenzoic acid The Kolbe-Schmitt reac tion IS used to prepare salicylic acid in the synthesis of as pinn  [c.1287]

Kolbe Schmidt reaction [ALKYLPHENOLS] (Vol 2)  [c.546]

This second reaction leads to the small amount of branching (usually less than 5%) observed in the alcohol product. The alpha olefins produced by the first reaction represent a loss unless recovered (8). Additionally, ethylene polymerisation during chain growth creates significant fouling problems which must be addressed in the design and operation of commercial production faciUties (9).  [c.456]

The second reaction is called the Fischer-Tropsch synthesis of hydrocarbons. Depending on the conditions and catalysts, a wide range of hydrocarbons from very light materials up to heavy waxes can be produced. Catalysts for the Fischer-Tropsch reaction iaclude iron, cobalt, nickel, and mthenium. Reaction temperatures range from about 150 to 350°C reaction pressures range from 0.1 to tens of MPa (1 to several hundred atm) (77). The Fischer-Tropsch process was developed iadustriaHy under the designation of the Synthol process by the M. W. Kellogg Co. from 1940 to 1960 (83).  [c.416]

The second and third reactions are economical, but the first is not. The second reaction is used in a process where HCN is oxidized to (CN)2 and hydrolyzed in the presence of a strong acid catalyst to give oxamide. The third reaction is employed in a newly developed process where diaLkyl oxalates are converted to oxamide by the ammonolysis reaction. This reaction easily proceeds without catalysts and quantitatively gives oxamide as a powder.  [c.463]

Alkylphenols undergo a carboxylation reaction known as the Kolbe Schmidt reaction. In the following example, the phenolate anion of /)-nonylphenol (15) reacts with carbon dioxide under pressure. Neutralization generates a sahcyhc acid (16) (10).  [c.60]

The first reaction, the addition of formaldehyde to the amino compound, is catalyzed by either acids or bases. Hence, it takes place over the entire pH range. The second reaction joins the amino units with methylene links and is catalyzed only by acids. The rates of these reactions have been studied over a broad range of pH (28). The results are presented in Figure 1.  [c.323]

For this second reaction Kjgs = 181 x 10" and hence pK, for ammonia solution is 4.75. The entity NHj. H2O is often referred to as ammonium hydroxide, NH4OH, a formula which would imply that either nitrogen has a covalency of five, an impossible arrangement, or that NH4OH existed as the ions NH4 and OH". It is possible to crystallise two hydrates from concentrated ammonia solution but neither of these hydrates is ionic. Hence use of the term ammonium hydroxide is to be discouraged in favour of ammonia solution .  [c.217]

The above are examples of the Claisen - Schmidt reaction. The formation of p-nitrostyrenes by reaction of nitroalkanes with aromatic aldehydes in the presence of aqueous alkali may be included under the Claisen- hmidt condensation  [c.709]

Chapter VI. Reductions with potassium borohydride (VI,11) Oppen-auer oxidation (VI,13) epoxidation and hydroxylation of ethylenic compounds (VI,15) Arndt Eistert reaction (VI,17) Darzens glycidio ester condensation (VI,18) Erlenmeyer azlactone reaction (VI,19) Mannich reaction (VI,20) Michael reaction (VI,21) Schmidt reaction (VI,23) Stobbe condensation (VI,24) Willgerodt reaction (VI,25) uns5mimetrical diaryls (VI,27) syntheses with organolithium compounds (VI,28) syntheses with organosodium compounds (VI,29) syntheses with organocadmium compounds (VI,30) some electrolytic syntheses (VI,31) chromatographic adsorption (VI,33) ring enlargement with diazomethane (VI,34).  [c.1191]

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction  [c.1210]

Pinacol-pinacolone rearrangement Prileschajew epoxidation reaction Reformataky reaction Reimer-Tiemanii reaction Rosenmund reduction Sandmeyer reaction Schiemaim reaction Schmidt reaction or rearrangement Schotten-Baumann reaction Skraup reaction Sommelet reaction.  [c.1211]

Appavatus-. For the first reaction a 500-ml round-bottomed flask with a thermometer and a gas outlet, connected with a tube filled with calcium chloride for the second reaction a 100-ml round-bottomed flask with a thermometer.  [c.177]

To a vigoroosly stirred solution of 0.40 mol of sodium in 1.2 1 of anhydrous liquid ammonia was added in 1 g portions 0.42 mol of powdered selenium. Thirty minutes after this addition 0.6 mol of ethyl bromide was introduced in 5-g portions at intervals of a few seconds. The ammonia was allowed to evaporate overnight and to the remaining mass were added 500 ml of water. After dissolution of the salt the diselenide was extracted with three 100-ml portions of diethyl ether. The ethereal solutions were dried over magnesium sulfate and subsequently concentrated in a water-pump vacuum, giving diethyl diselenide in more than 953 yield. The product was dissolved in 100 ml of diethyl ether and this solution was added to 1 1 of liquid ammonia in the second reaction flask. Small pieces of 0.05 g (freshly cut) of lithium were introduced through the tube in 30 min with vigorous stirring.  [c.235]

IS not oxidation-reduction The second reaction is oxidation-reduction (CH3)3CH + Brj -------------> (CH3)3CBr + HBr  [c.1203]

We can monitor the progress of this reaction by coupling it to a second reaction in which 12-MPA is reduced to form heteropolyphosphomolybdenum blue, PMB,  [c.625]

The first of these reactions takes place at temperatures of about 150°C, the second reaction proceeds at about 550—660°C. Typical furnaces used to carry out the reaction include cast-iron retorts the Mannheim mechanical furnace, which consists of an enclosed stationary circular muffle having a concave bottom pan and a domed cover and the Laury furnace, which employs a horizontal two-chambered rotating cylinder for the reaction vessel. The most recent design is the Cannon fluid-bed reactor in which the sulfuric acid vapor is injected with the combustion gases into a fluidized bed of salts. The Mannaheim furnace has also been used with potassium chloride as the feed.  [c.445]

There are many variations to this basic type of EIA. These include variations aimed at enhancing or increasing the sensitivity and specificity of an assay. Eor example, an EIA may utilize enzyme amplification to increase the speed and sensitivity of an immunoassay. In this approach, the enzyme label in the EIA produces a substance which triggers a second enzyme-based system which can generate large quantities of color in a very short time. Thus the product of the enzymatic activity of the antigen—antibody—enzyme complex does not need to be detected rather it can serve as a catalyst to begin the second reaction. The second enzyme system can be present in relatively large quantities, faciUtating rapid color formation, because the second enzyme is silent and noninteractive with the assay until the first reaction product turns it on. Eor example, a standard microtiter plate-based EIA for thyroid stimulating hormone (TSH), using alkaline phosphatase as the enzyme, can be amplified by adding nicotine adenine dinucleotide phosphate (NADP ) and a second enzyme system such as alcohol dehydrogenase and hpoamide dehydrogenase, which requites NAD , produced by alkaline phosphatase-dephosphorylation of NADP , for the production of the colored formazan dye (20).  [c.26]

Current Methods. The general outline of the Kolbe-Schmitt reaction, as it is employed in the 1990s, is as follows. In the first step, phenol and hot aqueous caustic are mixed to produce the sodium phenate which is taken to dryness. Next, the phenate and dry carbon dioxide are introduced into the carbonator. Air is excluded to minimi2e oxidation and the formation of colored compounds. The gas—sohd mixture is agitated and heated, first at low temperature, followed by several hours at higher temperatures, to complete the formation of sodium sahcylate. Variations of this reaction have been noted in the hterature and are stiU being investigated (10,11). One reported scheme produces sahcyhc acid or substituted sahcyhc acids by reaction of a granulated alkah metal salt of the respective phenohc compound with CO2 in a fiuidi2ed bed at 20—130°C until at least 50—80% of the metal salt has been converted to  [c.286]


See pages that mention the term Schmidt reaction : [c.172]    [c.208]    [c.219]    [c.423]    [c.232]    [c.259]    [c.872]    [c.277]   
See chapters in:

Named organic reactions 2nd edition  -> Schmidt reaction


Named organic reactions 2nd edition (2005) -- [ c.251 , c.252 , c.253 ]