Sciencemadness Discussion Board

1-Acetylnaphthalene

Waffles SS - 23-10-2013 at 21:56
Quote:

Naphthyl Methyl Ketone

(1) Acetic anhydride (20.4 g.; 1 mol.) was gradually added to a well stirred mixture of aluminium
chloride (56 g. ; 2 mols.) in ethylene chloride (100 c.c.). After 3 hours stirring, a solution of naphthalene
(25.6 g.) in ethylene chloride (50 c.c.) was gradually added. The temperature was kept at 35c during
the addition, but was subsequently raised to 50c to complete the reaction. After decomposition with
dilute hydrochloric acid the product provided a fraction (20 g.; b. p. 163c/15 mm.; m. p. 9.0 and
mixed m. p. 9.5 with pure a-naphthyl methyl ketone) which was almost pure a-naphthyl methyl
ketone. Picrate analysis indicated 97.5% of a-ketone.
(2) A solution of acetyl chloride (8 g. ; 1 mol.) and aluminium chloride (14 g. ; 1 mol.) in ethylene
chloride (30 c.c.) was gradually added to a solution of naphthalene (13 g.) in ethylene chloride (30 c.c.)
at 35c. A ready reaction occurred, and a solid separated. The mixture was decomposed with dilute
hydrochloric acid, and the product provided a fraction (16 g. ; b. p. 163c/15 mm. ; m. p. 9.0c and mixed
m. p. 9.5 with pure a-naphthyl methyl ketone) which was almost pure a-naphthyl methyl ketone.
Picrate analysis indicated 98% of a-ketone. A similar result was obtained when the solution of naphthalene
was gradually added to the solution of acetyl and aluminium chlorides.

The acylation of naphthalene by the friedel–crafts reactionG.
BaddeleyJ.Chem. Soc.1949, S99-S103
DOI: 10.1039/JR9490000S99



Quote:

vogel2.jpg - 227kB

Vogel 5th.p.1010



I used CH2Cl2 as a solvent,100gr FeCl3 instead of AlCl3 and 42 gr AcCl and after evaporation of solvent got lot of tar.

What is reason of tar formation in FC reaction?Adding AcCl Solution slowly to Naphthalene in methylene chloride may prevent it?

And finally somebody has experience on making 1-Acetylnaphthalene or Acylation of Naphthalene by FC reaction?


[Edited on 24-10-2013 by Waffles SS]

kristofvagyok - 23-10-2013 at 23:17

Sorry for the rude description, but FeCl3 will fuck up the reaction.

Fe(III) is a mild oxidizer, but enough strong to oxidize naphthalene to binaphthalene, especially at elevated temperatures. I have made BINOL from naphthol by simply melting FeCl3-hexahydrate, mixing it with naphthol and keeping it at 60 °C.

Have you checked the reaction with TLC? How many products are in the tar?

Waffles SS - 23-10-2013 at 23:40

Thanks @kristofvagyok ,I used FeCl3 because unfortunately I dont have access to AlCl3.also i didnt Checked it by TLC(that is really viscous tar).

I repeated this reaction many times.when I kept temperature below 35c small amount of tar formed but last time i boiled solution for evaporating the solvent and i have to say huge amount of tar formed.i think your description is true but tar formation below 35c is little.May i have any chance for formation Acetylnaphthalene by this way and below 35C or i should change Catalys?
Quote:



http://en.wikipedia.org/wiki/Ibuprofen#Synthesis

What about HF/AC2O Method?(like acetylation of isobutylbenzene in making Ibuprofen)




[Edited on 24-10-2013 by Waffles SS]

UnintentionalChaos - 24-10-2013 at 00:13

I don't particularly think that you can simply oxidize unfunctionalized naphthalene to binaphthalene. I'm pretty sure that the oxidative coupling is related to the ability of 2-naphthol to tautomerize to a keto form and/or involves chelation to the phenolic oxygens.

However, you use DCM as a solvent. DCM is an alkyl chloride, naphthalene is an activated aromatic system, and AlCl3 promotes FC-alkylation. Seeing as how things like triphenylmethane can be made from benzene, AlCl3, and carbon tet (followed by reduction, http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0548), it would not be hard to believe that you created a huge mass of crosslinked naphthalene rings with methylene bridges with lots of extra chloromethyl groups sticking out in places.

Change your solvent.

[Edited on 10-24-13 by UnintentionalChaos]

Waffles SS - 24-10-2013 at 00:37

@UnintentionalChaos,
Thanks but i have many articles(One of them in the first post ) that mentioned Methylene Chloride or Ethylene Chloride are suitable for acylation of naphthalene.

I found interesting article but Naphthalene not mentioned
Quote:

Reactions on a Solid Surface. A Simple, Economical and Efficient Friedel-Crafts Acylation Reaction over Zinc Oxide (ZnO) as a New Catalyst

Zinc oxide (ZnO) catalyzes a rapid Friedel-Crafts acylation of various aromatic compounds with acid chlorides in solvent-free conditions at room temperature. The ZnO powder can be reused up to three times after simple washing with dichloromethane.
M. H. Sarvari, H. Sharghi, J. Org. Chem., 2004, 69, 6953-6956.
DOI: 10.1021/jo0494477




[Edited on 24-10-2013 by Waffles SS]