02-13-04 03:40
No 488243
From Rhodium's page Synthesis of Barbiturates (../rhodium /barbitu
"Pentobarbitone. (Called Nembutal or Pentobarbital.) 26.7 g of clean metallic sodium are dissolved in 400 g of anhydrous (dry) ethanol. To this, a solution of 100 g of 1-methyl butyl-ethyl malonic ester and 37.2 g of dry urea is added. The mixture is heated for 4 to 6 hours in an autoclave, or refluxed for 20 to 40 hours. The alcohol is then removed by distillation. The residue is dissolved in water and this aqueous solution is acidified with hydrochloric acid. The precipitated product is filtered, washed with cold water, and recrystallized from boiling water. Yield: depends on your ability to exclude H2O from the beginning of the reaction, mp: 127-130°C."
I've not yet been able to figure out how one would prepare this ester. Most discussions of malonic esters in organic chemistry involve the preparation of carboxylic acids.
19th century digital boy
(Moderator)
02-13-04 04:05
No 488246
From Bernsthen-Sudborough's Textbook of Organic Chemistry:
Ethyl malonate, malonic ester is usually obtained by passing hydrogen chloride into a solution of cyanoacetic acid (from chloroacetic acid) in absolute alcohol. It is a liquid of faint aromatic odor boiling at 198°, and having a remarkable similarity to aceto-acetic ester. Thus the hydrogen of the methylene groupe is replaced by sodium, through the influence of the carbonyl groups, which also bound to the methylene; and the resulting sodio-malonic ester readily exchanges the metal for alkyl when treated with a alkyl iodide. By this means, the higher homologues of ethyl malonate e.g. methyl, ethyl, propyl, butyl et cetera malonic esters are obtained. Further, the second hydrogen atom in these can be exchanged in exactly the same manner for sodium and then for alkyl, whereby dialkyl malonic acids are formed. The so called "malonic ester" synthesis is an important method for the preparation of the higher dibasic acids, being applicable even in complicated cases, Conrad & Bischoff Ann 204 121. It is also important for the preparation some of the higher fatty acids, as in the substituted malonic acids when heated above their melting points lose carbon dioxide and yield fatty acids.
Chemistry is our Covalent Bond
(Hive Bee)
02-13-04 04:17
No 488252
I am aware of laboratory preparations for diethyl malonate. I am searching for a preparation of "1-methyl butyl-ethyl malonic ester," also called "di-n Butyl ethyl 1-methyl-n-butylmalonate" (chemfinder doesn't recognize these terms, but that's what Professor Buzz and the Pharmaceutical Manufacturing Encyclopedia call it). The WWW doesn't know about these compounds either. I guess I will try Scifinder Scholar tomorrow.
19th century digital boy
(Chief Bee)
02-13-04 04:56
No 488261
Ethyl Diethylmalonate -> Ethyl 1-Methylbutyl Diethylmalonate
Patent US1842293
The Hive - Clandestine Chemists Without Borders
(Stranger)
02-16-04 18:36
No 489077
Hey
I have another way of preparing separate thiopentone isomers (R/S), Starting from citronellol
It's a patent (and tried, by me), but not american, 58 pages
Let me know if this number helps WO 00/24358
If not i can send the PFD file to whoever wants it
Let God Die And Rot