5-allylvanillin
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ref: L. Claisen and O. Eisleb, Ann., 401, 112 (1913).
This is just allylation of vanillin, then claisen rearrangement with heat to give the 5-allylvanillin. SWIM would be grateful if someone could translate...
Vanillinallylather, durch sechstundiges Kochen von Vanillin mit Alkohol, Pottasche und Allylbromid in theoretischer Menge gewinnbar, ist ein farbloses Liquidum, da, wie an einer Probe festgestellt wurde, beim Destillieren im Vakuum schon merkliche Umlagerung in C-Allylvanillin erleidet. Es wurde daher in undestilliertem Zustande verwandt.
5-allylvanillin: Die Reaktion beim Erhitzen des Allylathers ist lebhafter als in allen fruheren Fallen: mit einem Ruck steigt das Thermometer von 210 C auf nahezu 300 C, die Flussigkeit kommt in starkes Kochen. Es empfiehlt sich daher, die Operation in kleineren Mengen (nicht uber 50 g) vorzunehmen. Trotz der Lebhaftigkeit der Umlagerung verlauft dieselbe sehr glatt; wird nach Ablauf des Siedens noch eine Viertelstunde im Olbad auf 220 C erhitzt und dann im Vakuum destilliert, so erhalt man in einer Menge von 80 Proz. der Theorie ein fast farbloses Destillat, das sofort under vollstandig zu einer krystallinischen Masse erstarrt. Das Produkt wird gepulvert und aus heiBem Benzin unter Zustaz von etwas Benzol umkrystallisiert. Es riecht dann noch etwas nach Vanillin, dessen Vorhandensein sich auch in den folgenden Analysen kundgibt...
5-Allylvanillin krystallisiert (besonders schon aus heiBer verdunnter Essigsaure) in langen, flachen, glanzenden, farblosen Prismen. Schmelzp. 85-86 C, beobachtete Siedepunkte 178 C (12 mm) under 173 C (9 mm)...
This article is interesting, because they do a lot of similar stuff with eugenol. Also, if one allylates 5-allylvanillin to 5-allyl-4-allyloxy-3-methoxybenzaldehyde, then does another claisen, the product becomes 5-allyleugenol (Diallylguajacol). Furthermore, if one starts from eugenol and allylates to 4-allyloxy-3-methoxyallylbenzene and does a claisen we also get 5-allyleugenol (Diallylguajacol).
5-propenylvanillin
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ref: JACS, 74, pp.4263 (1952)
A mixture of 500 g. of potassium hydroxide and 150 cc. of water was heated by means of an electric hot-plate in a stainless steel beaker to 140 C and treated with virorous stirring with 200 g. of 5-allylvanillin. The mixture becaome thick and orange colored. The temperature was raised to 160 C, at which point the hot plate was turned off. The temperature continued to rise to 180 C, and the mixture became quite fluid. Stirring was continued, and the temperature remained above 160 C for about 15 minutes. When the temperature reached 120 C, the mixture was diluted with 4 liters of water to effect solution of the fused mass and was stirred until cool. The cold alkaline solution was acidified with dilute sulfuric acid, and teh oil which separated solidified upon stirring and cooling. The yield of crude 5-propenylvanillin was 200 g. or 100%. Recrystallization from either water or pet. ether gave white needles melting at 73 C.
5-formylvanillin
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ref: JACS, 74, pp.4263 (1952)
Similar treatment of cis-5-propenylvanillin with 250 g. of nitrobenzene, 100 g. of sodium hydroxide and 1000 g. of water at 165 C for one hour gave a reaction mixture which was diluted, cooled, and extracted with ether. The aqueous alkaline solution was acidified with sulfur diozide, cooled, and extracted with ether; the ether was dried and sitlled to yield 5.2 g. . of crude 5-carboxyvanillic acid which was recrysatllized from water to give colorless crystals melting at 280-281 C. The sulfur dioxide-saturated solution was acidified with sulfuric acid and boiled. The solution was cooled and extracted with ether. The ether was dried and distilled to yiled 44.0 g of 5-formylvanillin which, upon recrystallization from pet. ether (b.p. 65-110 C), gave colorless spherical crystals melting at 125-126 C.
They also have a synthesis for 5-carboxyvanillin starting from 5-propenyl-orthovanillic acid. It's a bit involved, but the yields are always good in every step.
So, give some ideas on what we can do with these. SWIM will give it some thought later this week.