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Structural formula of 1-tetralone
Ball-and-stick model of the 1-tetralone molecule
IUPAC name
Other names
α-Tetralone; 1-Tetralone
3D model (JSmol)
ECHA InfoCard 100.007.692
Molar mass 146.19 g·mol−1
Appearance clear light yellow[2] to dark brown[3] liquid
Density * 1.099 g·cm−3 (25 °C)[3]
Melting point 2–7 °C[3]
Boiling point * 255–257 °C[4]
  • 113–116 °C (8 hPa)[3]
Solubility soluble in diethylether,[5] benzene,[6] toluene und xylene[7]
Vapor pressure 2.7 Pa (20 °C)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

1-Tetralone is a bicyclic aromatic hydrocarbon with an α-keto group (a benzocycloalkanone) and can also be regarded as benzo-fused cyclohexanone. It is used as starting material for agricultural and pharmaceutical agents.


The carbon skeleton of 1-tetralone is also found in natural products such as the so-called Aristelegone A (4,7-dimethyl-6-methoxy-1-tetralone) from the family of Aristolochiaceae used in traditional Chinese medicine.[8]

1-Tetralone via oxidation of 1,2,3,4-tetrahydronaphthalene[edit]

As already described in 1933 by Heinrich Hock, 1,2,3,4-tetrahydronaphthalene tends to autoxidize and gradually forms the 1-hydroperoxide with atmospheric oxygen.[9] The heavy metal ion catalyzed air oxidation of 1,2,3,4-tetrahydronaphthalene with Cr3+[10] or Cu2+ in the liquid phase leads via the hydroperoxide to a mixture of the intermediate 1-tetralol and the final product 1-tetralone.[11]

Oxidation von Tetraloin zu 1-Tetralon

The boiling points of the main component 1-tetralone (255-257 °C) and the minor component 1-tetralol (255 °C)[4] are virtually identical, the latter is therefore removed by a chemical reaction.[6]

1-Tetralone by Friedel-Crafts reaction of 4-phenylbutyric acid[edit]

The starting compound 4-phenylbutanoic acid (whose sodium salt sodium phenylbutyrate is used to treat hyperammonaemia) is accessible from 3-benzoylpropanoic acid via catalytic hydrogenation, using a palladium contact catalyst with a yield of 96%.[5] 3-Benzoylpropanoic acid[12] itself can be obtained by a Haworth reaction (a variant of the Friedel-Crafts reaction) from benzene and succinic anhydride in 77-82 % yield. A recent patent claims the synthesis of 4-phenylbutanoic acid via a Friedel-Crafts acylation of benzene and γ-butyrolactone with aluminum chloride at 60 °C followed by a work up with dilute sodium hydroxide solution and subsequent acidification in 94% crude yield and 81% pure yield.[13]

The intramolecular cyclization of 4-phenylbutanoic acid to 1-tetralone can be achieved by heating with polyphosphoric acid in 75-86% yield.[5]

Cyclisierung von 4-Phenylbuttersäure zu 1-Tetralon

The acid-catalyzed cyclization can also be carried out with methanesulfonic acid.[14] The reaction yield is between 23 and 80%, it has been described as a teaching experiment for chemistry lessons.[15] 4-Phenylbutanoic acid can also be quantitatively converted into 1-tetralone by heating to 180 °C and addition of catalytic amounts of strong Lewis acids such as bismuth(III)bis(trifluoromethanesulfonyl)amide[16] [Bi(NTf2)3], which is relatively easily accessible.[7]

1-Tetralone by Friedel-Crafts reaction of 4-phenylbutanoic acid chloride[edit]

The use of the acid chloride (by reaction with phosphorus pentachloride) with overstoichiometric amounts of tin(IV) chloride (SnCl4) allows significantly shorter reaction times than the Friedel-Crafts acylation with 4-phenylbutanoic acid, total yields of 85-91 % be achieved according to the reported "method B".[6]

Synthese von 1-Tetralon über 4-Phenylbuttersäurechlorid

4-Phenylbutanoic acid chlorides with electron-donating groups can be cyclized to 1-tetralones under mild reaction conditions in yields greater than 90% using the strong hydrogen-bonding solvent hexafluoroisopropanol (HFIP).[17]

1-Tetralone by Friedel-Crafts reaction of γ-butyrolactone[edit]

The acylation of benzene with γ-butyrolactone with excess aluminum chloride produces 1-tetralone in yields of 91-96%.[6]

Synthese von 1-Tetralon mit gamma-Butyrolacton

A disadvantage of many variants of the Friedel-Crafts acylation is the use of large amounts of AlCl3, polyphosphoric acid or PCl5 for the preparation of the used acid chlorides, which give rise to disproportionate difficulties and produce major volumes of waste.

For the reaction of benzene with γ-butyrolactone, the use of solid acidic catalysts based on zeolites and aluminosilicates was proposed, but no statement of their efficiency was given.[18] However, the seven-membered ketone 1-benzosuberone is accessible using acidic catalysts, from the six-membered lactone δ-valerolactone.

Synthese von Dimethyl-α-Benzosuberon Synthese


1-Tetralone is a clear, light yellow to dark brown liquid with a faint odor,[19] which is immiscible with water. It is miscible with non-polar organic solvents.

Toxicological studies were dermally performed with rabbits, with an LD50 of 2192 mg·kg−1 body weight being observed.[3]

The refractive index measured was 1.5672 (20 °C, 589 nm)[4] to 1.5695.[20]


1-Tetralone can be reduced via a Birch reduction with lithium in liquid ammonia to 1,2,3,4-tetrahydronaphthalene in a with 96% yield.[21] The keto group can also be reduced to a secondary alcohol giving 1-tetralol in 70% yield, when a modified process is applied, using the addition of aqueous ammonium chloride solution after evaporation of the ammonia.[22]

Reaktionen von 1-Tetralon mit Li in Ammoniak

With calcium in liquid ammonia, 1-tetralone is reduced to 1-tetralol at -33 °C in 81% yield.[23]

The methylene group in α-position to the keto group is particularly reactive and can be converted with formaldehyde (in the form of the trimeric paraldehyde) to 2-methylene-1-tetralone in the presence of the trifluoroacetic acid salt of N-methylaniline with yields up to 91% .

Synthese von 2-Methylen-1-tetralon aus 1-Tetralon

The 2-methylene ketone is stable at temperatures below -5 °C, but fully polymerizes at room temperature within 12 hours.[24]

In the Pfitzinger reaction of 1-tetralone with isatin, a compound called tetrofan (3,4-dihydro-1,2-benzacridine-5-carboxylic acid) is formed.

Synthese von Tetrophan

The reactivity of the α-methylene group is also exploited in the reaction of 1-tetralone with methanol at 270-290 °C, which produces via dehydrogenation and formation of the aromatic naphthalene ring system 2-methyl-1-naphthol in 66% yield.[25]

Synthese von 2-Methyl-1-naphthol

In the reaction of the oxime of 1-tetralone with acetic anhydride, aromatization of the cycloalkanone ring gives N-(1-naphthyl)acetamide[26] which acts like 2-(1-Naphthyl)acetic acid as a synthetic auxin.

Synthese von N-(1-Naphthyl)acetamid

The tertiary alcohol formed in the Grignard reaction of 1-tetralone with phenylmagnesium bromide reacts with acetic anhydride upon elimination of water to 1-phenyl-3,4-dihydronaphthalene, which is dehydrated with elemental sulfur in an overall yield of about 45% to 1-phenylnaphthalene.[27]

Synthese von 1-Phenylnaphthalin aus 1-Tetralon

The ruthenium(II)-catalyzed arylation of 1-tetralone using phenyl boronic acid neopentyl glycol ester gives 8-phenyl-1-tetralone in up to 86% yield.[28]

Synthese von 8-Phenyl-1-tetralon aus 1-Tetralon

With 5-aminotetrazole and an aromatic aldehyde, 1-tetralone reacts in a multi-component reaction under microwave irradiation to form a four-membered heterocyclic ring system.[29]

Multikomponentenreaktion von 1-Tetralon mit Aminotetrazol und aromatischem Aldehyd

The by far the most important application of 1-tetralone is in the synthesis of 1-naphthol by aromatizing dehydrogenation, e.g. on platinum catalysts at temperatures of 200 to 450 °C.[30]

Synthese von 1-Naphthol aus 1-Tetralon

1-Naphthol is the starting material for the insecticide carbaryl and the beta-blockers propranolol[31] and nadolol,[32][33] as well as for the antidepressant sertraline[34] and the anti-protozoan therapeutic atovaquone.[35]

The use of 1-tetralone as a poison against clothes moths[19] has not prevailed despite its "hardly by the human sense noticeable unpleasant odor" on the market.


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