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AvBaeyer
National Hazard
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Registered: 25-2-2014
Location: CA
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It is critical that the oxalic acid is anhydrous. I have done the OrgSyn prep of dimethyl oxalate. I dehydrated the oxalic acid dihydrate by gently
heating a weighed amount in an evaporating dish over moderate heat on a hot plate with occasional stirring. It took about 2 hours to lose the
theoretical amount of water.
In the OrgSyn prep it is important to carry out the second recrystallization as the initial crystalline product is quite acidic to congo red paper. I
have only done this prep once and realized a 61% yield of pure ester.
AvB
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Corrosive Joeseph
National Hazard
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Synthesis of Dimethyl Carbonate from Urea and Methanol over ZnO.
Wang, M., Zhao, N., Wei, & Sun, Y. (2005).
Industrial & Engineering Chemistry Research, 44(19), 7596–7599.
https://sci-hub.tw/10.1021/ie0504553
Synthesis of dimethyl carbonate from urea and methanol
Polyakov et al.
DGMK Tagungsbericht 2012(3):203-209
https://www.researchgate.net/publication/288551787_Synthesis...
/CJ
Being well adjusted to a sick society is no measure of one's mental health
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clearly_not_atara
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So recently I found a methylation of phenols which apparently uses sodium methyl sulfate "NaCH3SO4":
The prep of anisic acids and O-anisic acid — described as "methylsalicylsaüre" — in the old German paper simply used "NaCH3SO4", described as a
salt of "methylschwefelsaurem" translated by Google as "methylsulfuric acid", though the authors also tried and preferred dimethylsulfate. We can be
confident that "methylsalicylic acid" (literal translation) here means 2-methoxybenzoic acid or o-anisic acid, because:
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Anissaure war von mirI0) und L a d e n b u r g " ) genau so
aus den Aethern der p - OxybenzoBsaure dargestellt worden,
wie ich die Methylsalicylsaure erhalten hatte.
Anisic acid was prepared by me[10] and Ladenburg[11] from the etherification of p-hydroxybenzoic acid in exactly the
same way as I had obtained methylsalicylic acid.
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5 g Salicylsaure, 3,6 g Aetznatron entsprechend 2,5 Mol.,
7 g SO4CH3Na und 30 g Wasser wahrend funf Stunden am
aufsteigenden Kuhler erhitzt, lieferten 3 , s g Methylsalicylsaure,
also 60 pC. der theoretischen Ausbeute. Bei diesem Versuche
wie bei den folgenden wurde die Illethylsalicylsaure von unver-
anderter Salicylsaure durch Erwarmen mit Kalkmilch getrennt.
5 g of salicylic acid, 3.6 g of caustic soda corresponding to 2.5 mol,
7 g of SO4CH3Na, and 30 g of water, heated for five hours on an ascending condenser [I think this means "refluxed"], yielded 3.5 g of methylsalicylic
acid,
i.e., 60 pC of the theoretical yield. In this experiment, as in the following ones, the methylsalicylic acid was separated from the unchanged
salicylic acid by heating with milk of lime.
I think the implication here is that the calcium salicylate (Ksp = 4.49*10-6, compare Ksp Ca(OH)2 =
5*10-6) remains in the solids and the calcium methylsalicylate (similar to calcium benzoate, solubility probably about 10% at 100 C) is
obtained in the filtrate
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ia800805.us.archive.org/view_archive.php?archive=/13/items/crossref-pre-1909-scholarly-works/10.1002%252Fjlac.19023250205.zip&file=10.1002%252Fjla
c.19053400203.pdf
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I believe that this would also work on ring-hydroxylated cinnamic acids, such as coumaric acid and sinapic acid, since it seems to be regioselective
for phenol methylation. It might work on other phenols. Because it involves strong alkali at reflux I think it might not work for salicylaldehydes.
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