Rosenmund

Barium sulphate is frequently used as a support for the palladium (compare the Rosenmund reduction of add chlorides. Section IV.120) barium carbonate... 

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. ... 

The Pd-catalyzed hydrogenoiysis of acyl chlorides with hydrogen to give aldehydes is called the Rosenmund reduction. Rosenmund reduction catalyzed by supported Pd is explained by the formation of an acylpalladium complex and its hydrogenolysis[744]. Aldehydes can be obtained using other hydrides. For example, the Pd-catalyzed reaction of acyl halides with tin hydride gives aldehydes[745]. This is the tin Form of Rosenmund reduction. Aldehydes are i ormed by the reaction of the thio esters 873 with hydrosilanes[746,747]. 

The reduction of acyl halides with hydrogen to form aldehydes using Pd catalyst is well known as the Rosenmund reduction[756]. Some acyl chlorides give decarbonyiation products rather than aldehydes under Rosenmund conditions. The diene 890 was obtained by decarbonyiation in an attempted Rosenmund reduction of acetyloleanolic acid chloride (889)[757], Rosenmund reduction of sterically hindered acyl chlorides such as diphenyl- and tnpheny-lacetyl chloride (891) gives the decarbonylated products 892[758],... 

From these facts, a mechanism of the Rosenmund reduction has been proposed, in which the formation of the acylpalladium species 893 is the first step of the aldehyde formation and also the decarbonylation, although the Rosenmund reduction proceeds under heterogeneous conditions[744]. 

The acylpalladium complex formed from acyl halides undergoes intramolecular alkene insertion. 2,5-Hexadienoyl chloride (894) is converted into phenol in its attempted Rosenmund reduction[759]. The reaction is explained by the oxidative addition, intramolecular alkene insertion to generate 895, and / -elimination. Chloroformate will be a useful compound for the preparation of a, /3-unsaturated esters if its oxidative addition and alkene insertion are possible. An intramolecular version is known, namely homoallylic chloroformates are converted into a-methylene-7-butyrolactones in moderate yields[760]. As another example, the homoallylic chloroformamide 896 is converted into the q-methylene- -butyrolactams 897 and 898[761]. An intermolecular version of alkene insertion into acyl chlorides is known only with bridgehead acid chlorides. Adamantanecarbonyl chloride (899) reacts with acrylonitrile to give the unsaturated ketone 900[762],... 

Rosemary extract Rosemary oil [8000-25-7] Rosenmund reduction Rose oil... 

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

The pressure version of the enclosed agitated filter is known as the Rosenmund filter it uses a screw conveyor to convey the cake to a central cake discharge hole. 

Reduction of Acid Chlorides to Aldehydes. Palladium catalysis of acid chlorides to produce aldehydes is known as the Rosenmund reduction and is an indirect method used in the synthesis of aldehydes from organic acids. 

The catalyst commonly used in this method is 5 wt % palladium supported on barium sulfate inhibited with quinoline—sulfur, thiourea, or thiophene to prevent reduction of the product aldehyde. A procedure is found in the Hterature (57). Suitable solvents are toluene, benzene, and xylene used under reflux conditions. Interestingly, it is now thought that Rosenmund s method (59) originally was successful because of the presence of sulfur compounds in the xylene used, since the need for an inhibitor to reduce catalyst activity was not described until three years later (60). 

Rosenmund reaction is the action between acid chloride and hydrogen in the presence of palladium catalyst to produce aldehydes... 

Aristolochic Acid. Rosenmund and Reichstein prepared their material from roots and rhizomes of A. Sipho. It has the formula Cj HjiO N, m.p. 275° (dec.), and forms a methyl ester, m.p. 280° (dec.), [a]n 0°, which is difficult to saponify and on. hydrogenation gives a bright yellow substance, m.p. 312°, which forms a diacetyl... 

A common method for the preparation of alkyl cyanide 2 is the treatment of corresponding alkyl halides 1 with cyanide. The corresponding reaction with aromatic substrates is called the Rosenmund-von-Braun reaction. 

The name Rosenmund reduction is used for the catalytic hydrogenation of an acyl chloride 1 to yield an aldehyde 2. 

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