Europaisches Patentamt 19 European Patent Office Office europeen des brevets (TT) Publication number: 0 380 288 B1 © EUROPEAN PATENT SPECIFICATION © Date of publication of patent specification © int. ci.5 : C07C 13/48, C07C 2/72, 30.03.94 Bulletin 94/13 C07C 2/68 (21) Application number : 90300679.9 © Date of filing : 23.01.90 @) Process for preparing 1 ,1 ,3,4,4,6-hexamethyl-1 ,2,3,4-tetrahydronaphtalene. (§) Priority: 27.01.89 US 303356 (56) References cited : CHEMICAL ABSTRACTS, vol. 75, no. 13, 27 September 1971, abstract no. 88213d, Colum- (43) Date of publication of application bus, Ohio, US; E. J. EISENBRAUN, 01.08.90 Bulletin 90/31 "Acid-catalyzed alkylation and cyclialkylation of the cymenes with isobutylene and related olefins " (45) Publication of the grant of the patent : PATENT ABSTRACTS OF JAPAN, vol. 3, no. 30.03.94 Bulletin 94/13 147 (C-66), 5 December 1979; & JP-A-54 125 647 PATENT ABSTRACTS OF vol. © Designated Contracting States : JAPAN, 5, no. BE CH DE DK ES FR GB IT LI NL 102, (C-61)(774), 2 July 1981; & JP-A-56 43221 PATENT ABSTRACTS OF JAPAN, vol. 6, no. 110 (C-109)(988), 22 June 1982; & JP-A-57 (56) References cited : 40420 EP-A- 0 089 207 GB-A- 2 018 816 US-A- 3 856 875 (73) Proprietor : Union Camp Corporation US-A- 4 551 573 1600 Valley Road Wayne New Jersey 07470 - 2066 (US) (72) Inventor : Frank, Walter C. 244 Forrest Drive Holland, PA 18966 (US) (74) Representative : Jones, Helen Marjorie Meredith et al Gill Jennings & Every, Broadgate House, 7 Eldon Street London EC2M 7LH (GB) CO oo 00 CM o 00 CO Note : Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been LU filed until the opposition fee has been paid (Art. 99(1) European patent convention). Jouve, 18, rue Saint-Denis, 75001 PARIS EP 0 380 288 B1 Description The present invention relates to an improved process forthe production of 1 ,1 ,3,4,4,6-hexamethyl-1 ,2,3,4- tetrahydronaphthalene, referred to herein as HMT, for brevity. 5 HMT and other alkyl-substituted tetrahydronaphthalenes are of significant importance to the perfumery as well as other industries. By conventional acylation processes, HMT, for example, can be converted to 7- acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene, a well known musk perfume. Because of their clean musk fragrance and ability to retain that fragrance over long periods of time, these HMT derivatives are of great commercial value as synthetic musk perfume substitutes forthe expensive, natural musk perfumes 10 of the macrocyclic ketone series. Consequently, various synthetic methods have been proposed for the pro- duction of HMT and other related intermediates useful in the perfumery or other industries. Cobb, U.S. Patent No. 4,551,573 entitled "Alkylation of Aromatic Compounds" (the '573 patent), for exam- ple, broadly discloses a process for the alkylation and cyclialkylation of aromatic compounds with olefinic com- pounds in the presence of a catalyst consisting essentially of aluminum halide and elemental iodine. Aromatic 15 compounds described in the '573 patent include monocyclic, bicyclic or tricyclic aromatic compounds having 6 up to 30 carbon atoms, including compounds of the formula H 20 25 R3 30 [V] wherein each of R1 through R5 is independently selected from hydrogen and through C10 alkyl or cycloalkyl radical. Particular aromatic compounds disclosed as useful are para-cymene, para-met hylcyclohexyl benzene, para-met hylcyclopentyl benzene, para-et hylcyclopent yl benzene, para-ethylcyclohexylbenzene, benzene, tol- 35 uene, ortho or meta-xylene and tertiary-butylbenzene. Suitable olefinic compounds discussed encompass or- ganic compounds having at least one carbon-carbon double bond and any substituents which do not detrimen- tally interact with the catalyst employed the alkylation reaction. Preferred olefinic compounds include com- pounds of the Formula 40 R9 R6 X / C = C 45 wherein each of R6, R7, R8 and R9 are independently selected from hydrogen and through C10 alkyl or cy- cloalkyl radicals. In addition, R6 and R7 can be joined as part of a polymethylene radical or a halogen-, alkyl- or cycloalkyl-substituted polymethylene radical having about 2 to about 20 carbon atoms, i.e., a carbocyclic so compound with an exocyclic double bond. Further, R6and R9can be similarly joined as part of a polymethylene radical or a halogen-, alkyl- or cycloalkyl-substituted polymethylene radical having about 2 to about 20 carbon atoms, i.e., a carbocyclic compound with an endocyclic double bond. Particularly specified are isobutylene, 2-methyl-1-butene, 2-methyl-2-butene, 2,3-dimethyl-2-butene, neohexene (3,3-dimethyl-1-butene), diisobu- tylene-1, 2-butene, 2-pentene, 1-methylcyclohexene, 1-methylcyclopentene and 2-hexene. In addition, diiso- 55 butylene-2 is claimed as an olefinic compound, although it is not specified in the text of the patent. The patent also notes that a mixture of olefinic compounds can be employed, in which case one of the olefins may function as a sacrificial agent. Acombination of neohexene and isobutylene is a suggested mixture of such olefins. Suit- able aluminum halide compounds include aluminum tribromide, dichloroaluminum bromide, dibromoaluminum 2 EP 0 380 288 B1 fluoride, aluminum triiodide, and aluminum chloride, with aluminum chloride being preferred. The products of the reactions described in the '573 patent encompass aromatic compounds represented by the Formula 10 wherein each R is independently a through C40 alkyl orcycloalkyl radical and x is an integer from at least one up to 6. One or more of the R groups may be halogen, but not all R groups of the product are halogen. Particular compounds specified include tertiary-butyl -meta-xylene, di-tertiary-butyl-toluene, tertiary-amyl-xy- 15 lene, secondary-hexyl-xylene, and tertiary-hexyl-xylene. Other products include indanes of the general struc- ture 4 5 20 7 1 25 and tetrahydronaphthalene compounds of the general Formula 5 4 30 8 1 35 such indanes and tetrahydronaphthalenes having widely varying substitution patterns. Specific indanes and tetrahydronaphthalenes include 1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene, 1,1,3,3,5-pentame- 40 thylindane, 1,1,2,3,3,5-hexamethylindane and 1,1,3,5,5-pentamethylindane. Other synthetic methods include those described in Wood etal., U.S. Patent No. 3,856,875 entitled "Proc- ess for Producing 1 ,1 ,3,4,4,6-Hexamethyl-1 ,2,3,4-Tetrahydronapthalene [sic] (HMT)", which discloses a proc- ess for the preparation of HMT wherein an equivalent or excess amount of para-cymene is reacted with a sub- stantially equal molar solution of neohexene and a tertiary alkyl halide in the presence of an effective amount 45 of an anhydrous aluminum halide catalyst suspended in a reaction-compatible solvent. Although any tertiary alkyl halide can be employed in the disclosed process, tertiary butyl chloride, tertiary amyl chloride and 2,5- dichloro-2,5-dimethylhexane are noted as preferred. The process is described as having a solvent dependen- cy, with the satisfactory solvents being ethylene dichloride, chloroform, methylene dichloride, 1,1,2,2-tetra- chloroethane, 1,2-dichloroethylene, 1,2,3-trichloropropane, 1,1,2-trichloroethane, monochlorobenzene, fluo- 50 robenzene, ortho-dichlorobenzene, and para-xylene. Numerous solvents were deemed unsatisfactory for use in the disclosed process, such solvents including nitromethane, benzene, nitrobenzene, para-cymene, n-hex- ane, 1,2,2-trichloroethylene, carbon tetrachloride, 1,1,1-trichloroethane, carbon disulfide, 1,1,2,2,2-penta- chloroethane, 1,2-dichloropropane, 1,1-dichloroethylene, and 1,1-dichloroethane. These unsatisfactory sol- vents are said to yield substantially poorer results. 55 Wood, U.S. Patent No. 3,246,044 entitled "Process for Making 1 ,1 ,3,4,4,6-Hexamethyl-1 ,2,3,4-Tetrahydro- naphthalene," discloses a process for preparing HMT which includes reacting an alpha.para-dimethylstyrene derivative such as dimethyl-para-tolyl-carbinyl halide, and neohexene in the presence of a catalyst such as aluminum chloride, aluminum bromide and ferric chloride, or other Friedel-Crafts catalysts, at low tempera- tures. Suitable solvents are listed as ethylene dichloride or carbon tetrachloride, or other inert chlorinated hy- 3 EP 0 380 288 B1 drocarbon solvents. It is noted that other solvents such as nitrobenzene and nitromethane, may be used, but the yield of desired product is indicated as generally being lower when such solvents are employed. Sato et al., U.S. Patent No. 4,284,818 entitled "Process for Preparing Hexamethyltetrahydronaphtha- 5 lenes," describes a process for producing HMT comprising reacting para-cymene with a 2,3-dimethyl butene using a catalytic amount of anhydrous aluminum halide in the presence of a secondary alkyl halide, tertiary alkyl halide, propargyl halide orallyl halide. It is noted that both the 2,3-dimethyl-1 -butene and 2,3-dimethyl- 2-butene can be employed as the 2,3-dimethyl butene reagent, however, 2,3-dimethyl-1 -butene was said to yield better results. The reaction is generally carried out using a solvent, such solvents including aliphatic hy- 10 drocarbons, halogenated aromatic hydrocarbons, and halogenated aliphatic hydrocarbons. Japanese Patent Publication SHO 57-40420 discusses a method of making characterized by reacting para- cymene and neohexene in the presence of anhydrous aluminum halide as catalyst. Suitable anhydrous alu- minum halides are said to include aluminum chloride. The reaction is generally carried in a solvent, however, it is noted that it is possible to conduct the reaction without any additional solvent using excess para-cymene.