Limpricht

Leucine. Proust. Braconnot i8i8 1820/ 1 Limpricht. I Schulze and V Likiernik. i855" 1885/ 1 >> 1900... 

J. Liebio. Uebcrdic Oxydation organischer Vcrbindungen. Annalen, 1849, 70, 311-319. H. Limpricht. Notizcn, I. Darstellnng desLeudns aus dent Aldehyd der Valeriausdure. Annalen, 1855, 94, 243-244. 

The only method of preparative interest is the acetylation of benzoin, either with acetyl chloride 1 or with acetic anhydride.2 The melting point of acetyl benzoin was reported by Zinin as below roo°, by Jena and Limpricht as 75° but by later investigators as 82-83°. 

Limpricht,1 in 1873, prepared furan by heating barium 2-furancarboxylate with soda lime. It has since been prepared by the dry distillation of barium 2-furancarboxylate 2 in small amounts by distillation of calcium succinate 3 by the destructive distillation of resinous pine wood 4 by heating succinaldehyde with water at 1800 0 and by heating 2-furancarboxylic acid in a sealed tube.2... 

According to Limpricht, the acid may crystallize either in hydrated or in the anhydrous condition, but the transition temperature is not stated. The loss of water upon drying at ioo° shows the compound obtained in this experiment to be the monohydrate. 

The only practical method for the preparation of />-toluyl-o-benzoic acid is that proposed by Friedel and Crafts.1 Limpricht 2 has proposed a decrease in the quantity of aluminium chloride, but Heller and Schulke 3 and McMullen 4 have verified the importance of an excess of the condensing agent. 

The first indication of the existence of the other dinitrotoluene isomers can be found in the Limpricht s work. He was able to isolate from the nitration products the 3,6-isomer, besides the 2,4- and 2,6-isomers. In 1903 Zalo-ziecki... nitrated the aromatic fraction of Galicia oil and isolated the 2,4- and 3,6-nitro-toluenes. 

Although 2-furoic acid (pyromucic acid) was known to Scheele in 1780, furan was obtained only in 1870 by Limpricht. Furfural began to be produced commercially in the 1930s by the Quaker Oats Company and its subsidiary, the Miner Laboratory. It had been observed that oat husks (waste from breakfast cereals) afforded furfural on treatment with acids in about 10% yield, along with non-volatile cattle food. Among the many uses of furfural, one should mention (i) the manufacture of plastics based on the phenol-furfural-formaldehyde reaction, (ii) its use as selective solvent for aromatics in the petrochemical industry and oil refinement, and (iii) the separation of saturated from unsaturated fats (triglycerides) in the refinement of vegetable oils. Furfural can be recovered by steam distillation and recycled. 

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