Identification by smell? Haha, if you dare to identify a substance these days without an NMR, you're publically shot
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Nice article hype. The mentioned technique is also known as the PERKIN REACTION. As far as SWIM remembers, it's a technique developed in the late 1800s. It was very popular in the perfume industry (to make adulterated products, or rare substances). SWIM has some old stuff and adds some theoretical comment as a complement to the article:
1. Perkinsche Synthese: Zimtsäure aus Benzaldehyde und Essigsäure (Perkin synthesis method: cinnamic acid from benzaldehyde and acetic acid) [L Gattermann, Die Praxis des organischen Chemikers. 22. Auflage, 1930, pp 222-226]The Perkin reaction is a consequence of the general condensation reactions of aldehydes, viz. the separation of oxygen and 2 hydrogens from a methylene or methyl group. The latter's reactivities determine the reaction conditions. Aldehyde and aldehyde or ketone -> in cold acid or alkaline environment as catalist. Aldehyde and acid anhydride -> high temperatures, alkali salt (a).
The difference in reaction conditions is based on the reduction of the low reactivity of methyl groups (especially
alpha-methyl) in acid anhydride.
2. Phenole mit ungesättigten Seitenketten (Phenoles with unsaturated side chains) [Meyer, Jacobson, Lehrbuch der organischen Chemie. 1923, B II P I pp 430-436]Anethole is a main component from anis oil (from anis seeds), and can also be found in the oils of star anise, fennel and others. It can be produced synthetically by application of the Perkin reaction on anisaldehyde:
MeO-C
6H
4-CHO + CH
3CH
2COONa --> H
2O + MeO-C
6H
4-CH=CMeCOONa
MeO-C
6H
4-CH=CMeCOOH - CO
2 --> MeO-C
6H
4-CH=CH-CH
3This reaction is evidence for its molecular structure (...).
Isosafrol (b) is produced by heating safrol in a solution of an alcoholic base, or synthetically from piperonal in a similar way as anethole is made from anisaldehyde and isoeugenol from vanillin (!). Furthermore, this synthesis is prove for the location of the double bond in isosafrol.
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The Perkin reaction was initially used to prove the position of the double bond in the propene side chain on the phenyl (allyl vs propenyl). The method has been used for proving in a simple way the molecular difference between anethole/methyl chavicol, eugenol/isoeugenol, safrol/isosafrol etc. Interesting historical sidenote: the method has also been used for the structural elucidation of asarone. Although they found out that asarone was a propenyl derivative, they still didn't know the exact positions of the 3 MeO- groups on the phenyl ring (at least, in a 1923 book (cf. 2.)
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Mentioned references:
(a) Kalmin, Helv XI, 977 (1928)
(b) Grimaux, Ruotte, Bull.
11, 465 (1869) - Poleck, Ber.
17, 1940 (1884) - Eykman, Ber.
22, 2749 (1889);
23, 859 (1890); Rec. Trav. Chim.
14, 189 (1895) - Ciamician, Silber, Ber.
23, 1159 (1890);
25, 1470 (1892) - Tilden, Forster, Journ. Soc.
65, 332 (1894) - Angeli, Mole, Ber.
27 Ref, 799 (1894) - Wallach, Pond, Ber.
28, 2719 (1895) - Heffter, Chem. Centr.-Bl.
1896 I, 121 - Moureu, Compt. Rend.
122, 792 (1896)
Note: hypo, is your "Mr. Ch. Mourec" a typing error, and shouldn't it be "Mr. Ch. Moureu"? In that case, might be interesting to check the last reference from (b), if it would be the same person
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