Ladenburg

Ladder tron Ladenburg s formula Ladle metallurgy Ladles... 

Quinolinium 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide dimensions, 2, 110 Quinolinium iodide, 1-alkyl-Ladenburg rearrangement, 2, 300 Quinolinium iodide, 1-methyl-Ladenburg rearrangement, 2, 300, 335 Quinolinium iodide, [l-methyl-4-[3(5)-pyrazolyl]-blood sugar level and, 5, 291 Quinolinium perchlorate, 1-ethoxy-hydroxymethylation, 2, 300 Quinolinium perchlorate, 1-methyl-nitration, 2, 318 Quinolinium salts alkylation, 2, 293 Beyer synthesis, 2, 474 electrophilic substitution, 2, 317 free radical alkylation, 2, 45 nitration, 2, 188 reactions... 

In 1872 Ladenburg produced the first silicone polymer, a very viscous oil, by reacting diethoxydiethylsilane with water in the presence of traces of acid. 

Hyoscyamine, Ci,H2303N. This, the most commonly occurring alkaloid of the oup, was obtained by Geiger and Hesse from henbane. Ks hydrolysis into a base and an acid was observed by Hohn and Reichardt. The accepted, empirical formula is due to Ladenburg, who s owed that it was a physical isomeride of atropine. Hyoscyamine... 

When heated with acids or alkalis, hyoscyamine undergoes hydrolysis into tropine and dZ-tropic acid probably via conversion into atropine, and it is this alkaloid which is hydrolysed. According to Gadamer, when hyoscyamine is hydrolysed with cold water the products are inactive tropine and Z-tropie acid. Amenomiya has shown that Ladenburg and Hundt s partially synthetic d- and Z-atropines were probably mixtures of atropine with d- and Z-hyoscyamines. He resolved dZ-tropic acid into the d- and Z- forms, esterified these with tropine in 5 per cent, hydrochloric acid, and so obtained d- and Z-hyoscyamines, the latter identical with the natural alkaloid, d- and Z-Hyoscyamines have also been obtained by Barroweliff and Tutin by the resolution of atropine by means of d-camphorsulphonic acid. 

Tropic Acid. The constitution of both tropic and atropic acids is known from syntheses by Ladenburg et al. from acetophenone. The ketone (I) by treatment with phosphorus pentachloride was converted into a-dichloroethylbenzene (II), and this, by the action of potassium cyanide in alcohol, into ethoxycyanoethylbenzene (III), which on hydrolysis yielded ethylatrolactic acid (TV). The latter was converted by strong... 

The results so far recorded are those upon which Ladenburg chiefly based his formulae representing tropine and tropidine as A-methyl-J -tetrahydropyridines, substituted in position 2 by the residues. CHa. CH OH (or. CHOH. CH3) for tropine (XIV) and, CH CH for tropidine (XV) thus ... 

Hyoscine (Scopolamine, Atroscine), Ci,H2i04N. The name hyoscine was first used by Hohn and Reichardt for the basie hydrolytic product of hyoscyamine, now known as tropine. It was subsequently used by Ladenburg for a supposed isomeridc of atropine, Cj HjgOjN, isolated from the mother liquors of hyoscyamine. This was found by Schmidt, Hesse and others to be identical with scopolamine, Ci,H2i04N, obtained by Schmidt from Scopolia japonica. The name hyoscine has priority and is in use, but scopolamine is also employed, especially in Germany. 

The Ladenburg prism structure (V) can be definitely ruled out, since we know that the benzene ring lies in a plane, or very nearly in a plane. The chemical evidence is also unfavorable in this case. 

The pioneering work on polyorganosiloxanes dates back to 1863-1871, to the studies of Friedel, Crafts8 "10) and Ladenburg 11 However, it was F. S. Kipping and his coworkers who were first to demonstrate the polymeric siloxane structures in the early 1900 s12). Unfortunately, since their interest was mainly in small molecules, they did not recognize the importance of the polymers and polymerization in this field 13). 

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