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WO1998027030A1 - Process for the production of alpha methylstyrenes - Google Patents

Process for the production of alpha methylstyrenes Download PDF

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Publication number
WO1998027030A1
WO1998027030A1 PCT/US1997/022752 US9722752W WO9827030A1 WO 1998027030 A1 WO1998027030 A1 WO 1998027030A1 US 9722752 W US9722752 W US 9722752W WO 9827030 A1 WO9827030 A1 WO 9827030A1
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WIPO (PCT)
Prior art keywords
dimethyl phenyl
phenyl carbinol
acid salt
contacting
carbinol
Prior art date
Application number
PCT/US1997/022752
Other languages
French (fr)
Inventor
Chempolil Thomas Mathew
William Johnston Boyle
Zhenrong Qian
Original Assignee
Alliedsignal Inc.
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Filing date
Publication date
Application filed by Alliedsignal Inc. filed Critical Alliedsignal Inc.
Priority to AU57959/98A priority Critical patent/AU5795998A/en
Publication of WO1998027030A1 publication Critical patent/WO1998027030A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
    • C07C1/24—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms by elimination of water
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/35—Preparation of halogenated hydrocarbons by reactions not affecting the number of carbon or of halogen atoms in the reaction
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2527/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • C07C2527/02—Sulfur, selenium or tellurium; Compounds thereof
    • C07C2527/053—Sulfates or other compounds comprising the anion (SnO3n+1)2-
    • C07C2527/055—Sulfates or other compounds comprising the anion (SnO3n+1)2- with alkali metals, copper, gold or silver

Definitions

  • This invention relates to a process for the production of ⁇ -methylstyrenes.
  • the invention provides a process for producing ⁇ -methylstyrenes from ⁇ , ⁇ -dimethyl phenyl carbinols using an acid salt, which process produces the ⁇ -methylstyrenes in excellent yield with no significant byproduct formation.
  • ⁇ -methylstyrenes are used to produce certain copolymers as well as specialty polymers. Further, ⁇ -methylstyrenes find utility as intermediates in the production of fine chemicals.
  • ⁇ -methylstyrene is formed as a byproduct during the manufacture of phenol from cumene.
  • cumene undergoes air oxidation to form a product mixture of cumene hydroperoxide, ⁇ , ⁇ - dimethyl phenyl carbinol, and acetophenone.
  • This mixture then is contacted with an acid catalyst resulting in the formation of phenol and acetone, as well as ⁇ - methylstyrene formed from the ⁇ , ⁇ -dimethyl phenyl carbinol.
  • a problem with this process for producing ⁇ -methyl styrene is that yield loss is significant due to the formation of dimer and oligomer byproducts and a high-boiling condensation product with phenol. Additionally, ⁇ -methylstyrene is only a minor process product, the major products being phenol and acetone.
  • U.S. Patent No. 4,358,618 discloses a multi-step process in which a cumene hydroperoxide product mixture that contains ⁇ , ⁇ -dimethyl phenyl carbinol is reacted with an acid to form dicumyl peroxide. The dicumyl peroxide then undergoes decomposition using elevated temperatures to produce ⁇ -methylstyrene, phenol, and acetone.
  • U.S. Patent No. 4,310,712 discloses a process for enhancing ⁇ - methylstyrene production in which acetone and an acidic decomposition catalyst is mixed with cumene hydroperoxide. The mixture is flowed, without substantial backmixing, through a reactor with a controlled temperature to convert the cumene hydroperoxide to phenol, acetone, and ⁇ -methylstyrene.
  • the process of this invention provides for the production of ⁇ - methylstyrenes from a dimethyl phenyl carbinol. It has been discovered that ⁇ - methylstyrenes can be produced from dimethyl phenyl carbinols in essentially quantitative yields by treating a dimethyl phenyl carbinol with an acid salt. Also it has been discovered that the ⁇ , ⁇ -dimethyl phenyl carbinol can be produced in very high yields by treating cumene hydroperoxide with a reducing agent.
  • the invention provides a process for producing ⁇ -methylstyrenes comprising contacting a dimethyl phenyl carbinol with an effective amount of an acid salt under conditions suitable to produce an ⁇ - methylstyrene product.
  • the invention provides a process for producing ⁇ -methylstyrenes comprising: contacting a mixture comprising a cumene hydroperoxide with an effective amount of a reducing agent under conditions suitable to produce a mixture comprising a dimethyl phenyl carbinol; and contacting the dimethyl phenyl carbinol mixture with an effective amount of an acid salt under conditions suitable to produce an ⁇ -methylstyrene product.
  • dimethyl phenyl carbinols useful in the invention are of the formula:
  • R is an unsubstituted phenyl or phenyl substituted with one or more substituents which substituents are independently Ci to Gs alkoxy, C_ to Gs thioalkyl, cyano, C_ to C 2 dialkylamino, nitro, halogen, G to C 2 haloalkyl, or G to C 2 perfluoroalkyl.
  • substituents are independently Ci to Gs alkoxy, C_ to Gs thioalkyl, cyano, C_ to C 2 dialkylamino, nitro, halogen, G to C 2 haloalkyl, or G to C 2 perfluoroalkyl.
  • ⁇ , ⁇ -dimethyl phenyl carbinol is used.
  • the dimethyl phenyl carbinol may be in substantially pure form, which may be obtained by distillation, or in impure form.
  • impure form is meant that the dimethyl phenyl carbinol is a part of a mixture containing at least one other component.
  • the air oxidation of cumene produces a product mixture containing cumene hydroperoxide, ⁇ , ⁇ -dimethyl phenyl carbinol, unreacted cumene and acetophenone.
  • the air oxidation product mixture containing cumene, cumene hydroperoxide, ⁇ , ⁇ -dimethyl phenyl carbinol, and acetophenone may be treated with a reducing agent. This forms a mixture containing more ⁇ , ⁇ -dimethyl phenyl carbinol than found in the starting mixture, which increased amount of ⁇ , ⁇ - dimethyl phenyl carbinol is produced by the reduction of the cumene hydroperoxide present in the starting product mixture.
  • the ⁇ , ⁇ -dimethyl phenyl carbinol mixture may then be contacted with an acid salt to form an ⁇ - methylstyrene product.
  • the ⁇ , ⁇ -dimethyl phenyl carbinol product mixture may be purified by any convenient means, such as distillation, to recover substantially or totally pure dimethyl phenyl carbinol, which then may be contacted with the acid salt to produce ⁇ -methyl styrene product.
  • Reducing agents useful in the process of the invention are any suitable neutral or basic reducing agent known in the art including, without limitation, sodium sulfite, potassium sulfite, lithium sulfite, or ammonium sulfite. Preferably, sodium sulfite is used.
  • An effective amount of reducing agent is an amount sufficient to reduce essentially all of the cumene hydroperoxide to the dimethyl phenyl carbinol.
  • the amount of reducing agent used is generally from about 1.0 to about 2.0, preferably from about 1.2 to about 1.4 equivalents based on equivalents of the cumene hydroperoxide.
  • the reducing agent may be used as an aqueous solution and the reduction conducted by contacting, or mixing, the solution with cumene hydroperoxide.
  • Contacting of the cumene hydroperoxide and the reducing agent is performed by the controlled addition of the hydroperoxide into the reducing agent at reflux over period generally of from about 0.5 to about 6, preferably from about 1 to about 2 hours.
  • the resultant mixture is then heated at reflux.
  • the reaction time is generally from about 1 to about 6, preferably from about 2 to about 4 hours.
  • the acid salt useful in the invention are salts of acids having a pKa of about 5 or less, preferably, about 3 or less.
  • an acid salt of sulfuric acid is used.
  • the acid salt counterion may be ammonium or any alkali metal salt, including without limitation sodium, potassium, or lithium.
  • the counterion is sodium.
  • the amount of acid salt used is from about 0.1 to about 2.0, preferably from about 0.5 to about 1.0 weight percent based on the weight of the carbinol.
  • contacting of the dimethyl phenyl carbinol with the acid salt takes place in the presence of a solvent which may be any suitable solvent including, without limitation, toluene, benzene, hexane, heptane, or the like and mixtures thereof. More preferably, toluene is used.
  • the reaction time required will depend on the solvent used. Generally, reaction times will range from about 1 to about 20 hours, preferably from about 2 to about 15 hours. The reaction is carried out at the reflux temperature of the solvent.
  • ⁇ -methylstyrene product containing the desired ⁇ - methylstyrene and solvent.
  • the ⁇ -methylstyrene product may be purified by any convenient means, such as distillation, to recover purified ⁇ - methylstyrene.
  • Example 1 86.7 g (0.688 mol) sodium sulfite and 347 g water were charged into a 1 L, three-necked, round-bottomed flask equipped with a mechanical agitator, water- cooled condenser, heating mantle, and addition funnel. After the aqueous sodium sulfite solution was heated to 101° C, 300 g (0.529 mol) of 30 % 4-fluorocumene hydroperoxide in 4-fluorocumene were added from the addition funnel over 104 minutes at a temperature between 100 and 104° G The heating was continued at 98 to 104° C for 74 min.
  • Example 2 12.9 g (0.102 mol) sodium sulfite and 52 g water were charged into a 100 mL, three-necked, round-bottomed flask equipped with a mechanical agitator, water-cooled condenser, heating mantle, and addition funnel.
  • cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6% ⁇ , ⁇ -dimethyl phenyl carbinol and 0.5 % acetophenone by gas chromatographic analysis) were added from the addition funnel over 25 min at a temperature of 100 to 103° C.
  • the mixture was heated at reflux temperature of 115° C for 1 h, giving a quantitative conversion of ⁇ , ⁇ -dimethyl phenyl carbinol to ⁇ -methylstyrene (10.2 % ⁇ -methylstyrene by GC analysis).
  • Example 3 5.0 g (0.029 mol) of 80 % ⁇ , ⁇ -dimethyl phenyl carbinol, 0.02 g ammonium bisulfate and 30 g toluene were charged into a 100 mL, three-necked, round- bottomed flask equipped as in Example 2. The mixture was heated at reflux for 2 h at which point no more water was collected in the Dean-Stark separator. GC analysis of the reaction mixture showed a quantitative conversion of ⁇ , ⁇ -dimethyl phenyl carbinol to ⁇ -methylstyrene (3.4 g, 0.029 mol).
  • Example 4 The procedure of Example 3 was used except that 3.0 g (0.018 mol) of 80 % ⁇ , ⁇ -dimethyl phenyl carbinol, 25 g toluene, and 0.02 g potassium bisulfate were used. 2.1 g (0.018 mol) ⁇ -methylstyrene was produced in quantitative yield as determined by GC.
  • Example 5 5.0 g (0.032 mol) pure ⁇ , ⁇ -dimethyl 4-fluorophenyl carbinol, 0.05 g potassium bisulfate, and 25 g toluene were charged into a 100 mL, three-necked, round-bottomed flask equipped as in example 2. The mixture was heated at reflux for 73 min at which point no more water was collected in the Dean-Stark water separator. Gas chromatographic analysis of the reaction mixture showed a quantitative conversion of ⁇ , ⁇ -dimethyl 4-fluorophenyl carbinol to 4-fluoro ⁇ - methylstyrene (4.3 g, 0.032 mol).
  • Example 6 The procedure of Example 5 was used except that 5.0 g (0.032 mol) pure ⁇ , ⁇ -dimethyl 4-fluorophenyl carbinol, 25 g toluene, and 0.05 g ammonium bisulfate were used. 4.3 g (0.032 mol) 4-fluoro ⁇ -methylstyrene were produced in quantitative yield.
  • Example 5 The procedure of Example 5 was used except that 5.0 g (0.032 mol) pure ⁇ , ⁇ -dimethyl 4-fluorophenyl carbinol, 0.05 g sodium bisulfate, and 25 g heptane were used. The reaction ran at 102° C for 2 h, producing the product 4-fluoro ⁇ - methylstyrene (4.3 g, 0.032 mol) in quantitative yield.
  • Example 8 The procedure of Example 5 was followed except that 0.1 wt % sodium bisulfate (0.02 g) based on the pure ⁇ , ⁇ -dimethyl 4-fluorophenyl carbinol (20.3 g, 0.130 mol) in 31.5 g toluene were used. The mixture was heated at reflux for 2 h producing 4-fluoro ⁇ -methylstyrene (17.6 g, 0.130 mol) in quantitative yield as determined by GC.
  • Example 9 83.2 g (97 %, 0.51 mol) potassium sulfite and 260 g water were charged into a 1 L, three-necked, round-bottomed flask equipped with a mechanical agitator, water-cooled condenser, heating mantle, and addition funnel. After the aqueous sodium sulfite solution was heated to 100° C, 75.0 g (0.39 mol) cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % ⁇ , ⁇ - dimethyl phenyl cabinol and 0.5 % acetophenone by GC analysis) were added gradually from the addition funnel over 2 hours at a temperature of about 100° C.
  • cumene oxidation material 78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % ⁇ , ⁇ - dimethyl phenyl cabinol and 0.5 % acetophenone by GC analysis
  • the heating was continued at 100 - 120° C for 2 hours yielding a 60.2 g ⁇ , ⁇ - dimethyl phenyl cabinol mixture (86.8 % ⁇ , ⁇ -dimethyl phenyl cabinol, 12.6 % cumene, and 0.7 % acetophenone by GC analysis) after phase separation.
  • the organic phase was concentrated to remove cumene by rotary evaporation at 80° C under reduced pressure, leaving 51 g ⁇ , ⁇ -dimethyl phenyl cabinol in 98.6 % purity as an oily liquid, 96.4 % yield.
  • Example 10 The procedure of Example 9 was used except that 75.0 g (0.39 mol) cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % ⁇ , ⁇ -dimethyl phenyl carbinol and 0.5 % acetophenone by GC analysis), 64.5 g sodium sulfite, and 105 g water were used in the reduction step and that 50 g of the 98.6 % ⁇ , ⁇ -dimethyl phenyl carbinol obtained from the concentration by rotary evaporation, 0.5 g sodium bisulfate, and 60 g toluene were used in the dehydration step.
  • cumene oxidation material 78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % ⁇ , ⁇ -dimethyl phenyl carbinol and 0.5 % acetophenone by GC analysis
  • 64.5 g sodium sulfite
  • reaction was run at reflux for 2 h at which point GC analysis of the reaction mixture showed no significant evidence of ⁇ , ⁇ -dimethyl phenyl carbinol.
  • the reaction mixture was washed with 5 g water to remove the solid and distilled under reduced pressure using a Vigreux column yielding 41.5 g ⁇ -methylstyrene in 98.4 % purity, 96 % yield.

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Abstract

The invention provides a process for the production of α-methylstyrenes. In particular, the invention provides a process for producing α-methylstyrenes from dimethyl phenyl carbinols using an acid salt, which process produces the α-methylstyrenes in excellent yield with no significant byproduct formation.

Description

- I -
PROCESS FORTHE PRODUCTION OF ALPHAMETHYLSTYRENES
Field of the Invention This invention relates to a process for the production of α-methylstyrenes.
In particular, the invention provides a process for producing α-methylstyrenes from α,α-dimethyl phenyl carbinols using an acid salt, which process produces the α-methylstyrenes in excellent yield with no significant byproduct formation.
Background of the Invention
Industry uses α-methylstyrenes in a variety of applications. For example, α-methylstyrenes are used to produce certain copolymers as well as specialty polymers. Further, α-methylstyrenes find utility as intermediates in the production of fine chemicals.
It is known to produce α-methylstyrenes through the acid catalyzed dehydration of α,α-dimethyl phenyl carbinols using strong acids such as sulfuric or hydrochloric acid. In one process, pure α,α-dimethyl phenyl carbinol is used along with acidic silica and high temperatures to produce α-methylstyrene. This process is disadvantageous because the high temperatures used result in the formation of dimeric and oligomeric byproducts.
Additionally, it is known that α-methylstyrene is formed as a byproduct during the manufacture of phenol from cumene. In this process, cumene undergoes air oxidation to form a product mixture of cumene hydroperoxide, α,α- dimethyl phenyl carbinol, and acetophenone. This mixture then is contacted with an acid catalyst resulting in the formation of phenol and acetone, as well as α- methylstyrene formed from the α,α-dimethyl phenyl carbinol. A problem with this process for producing α-methyl styrene is that yield loss is significant due to the formation of dimer and oligomer byproducts and a high-boiling condensation product with phenol. Additionally, α-methylstyrene is only a minor process product, the major products being phenol and acetone.
A number of processes have been developed in attempt to increase the α- methylstyrene yield in the production of phenol from cumene. United States Patent No. 5,463,136 discloses a staged cumene hydroperoxide cleavage process. In the first stage, the cumene hydroperoxide is reacted with sul uric acid in a reflux cooled reactor to produce dicumyl peroxide product. This product then undergoes decomposition under isothermal conditions.
U.S. Patent No. 4,358,618 discloses a multi-step process in which a cumene hydroperoxide product mixture that contains α,α-dimethyl phenyl carbinol is reacted with an acid to form dicumyl peroxide. The dicumyl peroxide then undergoes decomposition using elevated temperatures to produce α-methylstyrene, phenol, and acetone.
U.S. Patent No. 4,310,712 discloses a process for enhancing α- methylstyrene production in which acetone and an acidic decomposition catalyst is mixed with cumene hydroperoxide. The mixture is flowed, without substantial backmixing, through a reactor with a controlled temperature to convert the cumene hydroperoxide to phenol, acetone, and α-methylstyrene.
All of these processes are hazardous because thermally unstable compounds, such as cumene hydroperoxide and dicumyl peroxide, must be handled at high temperatures. The processes also produce phenol and acetone as co- products, the success of producing commercial quantities of α-methylstyrene thus depending on the effective and economical disposal of these co-products. Therefore, a need exists for a method of producing α-methylstyrenes that avoids some of the disadvantages of these processes.
Description of the Invention and Its Preferred Embodiments The process of this invention provides for the production of α- methylstyrenes from a dimethyl phenyl carbinol. It has been discovered that α- methylstyrenes can be produced from dimethyl phenyl carbinols in essentially quantitative yields by treating a dimethyl phenyl carbinol with an acid salt. Also it has been discovered that the α,α-dimethyl phenyl carbinol can be produced in very high yields by treating cumene hydroperoxide with a reducing agent.
Thus, in one embodiment, the invention provides a process for producing α-methylstyrenes comprising contacting a dimethyl phenyl carbinol with an effective amount of an acid salt under conditions suitable to produce an α- methylstyrene product. In another embodiment, the invention provides a process for producing α-methylstyrenes comprising: contacting a mixture comprising a cumene hydroperoxide with an effective amount of a reducing agent under conditions suitable to produce a mixture comprising a dimethyl phenyl carbinol; and contacting the dimethyl phenyl carbinol mixture with an effective amount of an acid salt under conditions suitable to produce an α-methylstyrene product.
The dimethyl phenyl carbinols useful in the invention are of the formula:
CH3 R - C -CH3 OH wherein R is an unsubstituted phenyl or phenyl substituted with one or more substituents which substituents are independently Ci to Gs alkoxy, C_ to Gs thioalkyl, cyano, C_ to C2 dialkylamino, nitro, halogen, G to C2 haloalkyl, or G to C2 perfluoroalkyl. Preferably, α,α-dimethyl phenyl carbinol is used. The dimethyl phenyl carbinol may be in substantially pure form, which may be obtained by distillation, or in impure form. By impure form is meant that the dimethyl phenyl carbinol is a part of a mixture containing at least one other component. For example, in the production of phenol from cumene, the air oxidation of cumene produces a product mixture containing cumene hydroperoxide, α,α-dimethyl phenyl carbinol, unreacted cumene and acetophenone.
The air oxidation product mixture containing cumene, cumene hydroperoxide, α,α-dimethyl phenyl carbinol, and acetophenone may be treated with a reducing agent. This forms a mixture containing more α,α-dimethyl phenyl carbinol than found in the starting mixture, which increased amount of α,α- dimethyl phenyl carbinol is produced by the reduction of the cumene hydroperoxide present in the starting product mixture. The α,α-dimethyl phenyl carbinol mixture may then be contacted with an acid salt to form an α- methylstyrene product. Alternatively, the α,α-dimethyl phenyl carbinol product mixture may be purified by any convenient means, such as distillation, to recover substantially or totally pure dimethyl phenyl carbinol, which then may be contacted with the acid salt to produce α-methyl styrene product.
It is another discovery of the invention that contacting a cumene hydroperoxide with a reducing agent yields an α,α-dimethyl phenyl carbinol in essentially quantitative yields. Reducing agents useful in the process of the invention are any suitable neutral or basic reducing agent known in the art including, without limitation, sodium sulfite, potassium sulfite, lithium sulfite, or ammonium sulfite. Preferably, sodium sulfite is used. An effective amount of reducing agent is an amount sufficient to reduce essentially all of the cumene hydroperoxide to the dimethyl phenyl carbinol. The amount of reducing agent used is generally from about 1.0 to about 2.0, preferably from about 1.2 to about 1.4 equivalents based on equivalents of the cumene hydroperoxide. The reducing agent may be used as an aqueous solution and the reduction conducted by contacting, or mixing, the solution with cumene hydroperoxide.
Contacting of the cumene hydroperoxide and the reducing agent is performed by the controlled addition of the hydroperoxide into the reducing agent at reflux over period generally of from about 0.5 to about 6, preferably from about 1 to about 2 hours. The resultant mixture is then heated at reflux. The reaction time is generally from about 1 to about 6, preferably from about 2 to about 4 hours.
The acid salt useful in the invention are salts of acids having a pKa of about 5 or less, preferably, about 3 or less. Preferably, an acid salt of sulfuric acid is used. The acid salt counterion may be ammonium or any alkali metal salt, including without limitation sodium, potassium, or lithium. Preferably, the counterion is sodium. Generally, the amount of acid salt used is from about 0.1 to about 2.0, preferably from about 0.5 to about 1.0 weight percent based on the weight of the carbinol.
Preferably, contacting of the dimethyl phenyl carbinol with the acid salt takes place in the presence of a solvent which may be any suitable solvent including, without limitation, toluene, benzene, hexane, heptane, or the like and mixtures thereof. More preferably, toluene is used. The reaction time required will depend on the solvent used. Generally, reaction times will range from about 1 to about 20 hours, preferably from about 2 to about 15 hours. The reaction is carried out at the reflux temperature of the solvent.
Contacting of the dimethyl phenyl carbinol with the acid salt in the solvent results in the formation of an α-methylstyrene product containing the desired α- methylstyrene and solvent. Optionally, the α-methylstyrene product may be purified by any convenient means, such as distillation, to recover purified α- methylstyrene.
The process of the invention will be clarified further by the following non- limiting examples.
Examples Example 1 86.7 g (0.688 mol) sodium sulfite and 347 g water were charged into a 1 L, three-necked, round-bottomed flask equipped with a mechanical agitator, water- cooled condenser, heating mantle, and addition funnel. After the aqueous sodium sulfite solution was heated to 101° C, 300 g (0.529 mol) of 30 % 4-fluorocumene hydroperoxide in 4-fluorocumene were added from the addition funnel over 104 minutes at a temperature between 100 and 104° G The heating was continued at 98 to 104° C for 74 min. After phase separation, the organic phase was concentrated to remove 4-fluorocumene by rotary evaporation at 80° C under reduced pressure, leaving 78.8 g α,α-dimethyl 4-fluorophenyl carbinol in 98.5 % purity as an oily liquid, 96.6% yield.
70.0 g (0.477 mol) of the α,α-dimethyl 4-fluorophenyl carbinol, 0.7 g sodium bisulfate and 80 g toluene were charged into a 500 mL, three-necked, round-bottomed flask equipped with a magnetic stirrer, heating mantle, thermometer, water-cooled reflux condenser and Dean-Stark water separator filled with toluene. The reaction was run at reflux for 45 min and the reaction mixture filtered by suction to remove the solid and distilled under reduced pressure using a Vigreux column yielding 60.9 g 4-fluoro-α-methylstyrene in 98.9 % purity (98% yield). The product 4-fluoro-α-methylstyrene was identified by NMR and the bp of the product at ambient pressure was 165 - 169° G Example 2 12.9 g (0.102 mol) sodium sulfite and 52 g water were charged into a 100 mL, three-necked, round-bottomed flask equipped with a mechanical agitator, water-cooled condenser, heating mantle, and addition funnel. After the aqueous sodium sulfite solution was heated to 100° C, 15.0 g cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6% α,α-dimethyl phenyl carbinol and 0.5 % acetophenone by gas chromatographic analysis) were added from the addition funnel over 25 min at a temperature of 100 to 103° C. The heating was continued at 102° C for 2 h, yielding a 13.1 g α,α-dimethyl phenyl carbinol mixture (87.4 % α,α-dimethyl phenyl carbinol, 12.0 % cumene, and 0.6 % acetophenone by GC analysis) after phase separation.
A 5.0 g portion of the α,α-dimethyl phenyl carbinol mixture with 25 g toluene was placed in a 100 mL, three-necked, round-bottomed flask equipped with a magnetic stirrer, heating mantle, thermometer, water-cooled reflux condenser, and Dean-Stark water separator filled with toluene. To the resulting α,α-dimethyl phenyl carbinol solution (10.1 % α,α-dimethyl phenyl carbinol by GC analysis) was added 50 mg sodium bisulfate. The mixture was heated at reflux temperature of 115° C for 1 h, giving a quantitative conversion of α,α-dimethyl phenyl carbinol to α-methylstyrene (10.2 % α-methylstyrene by GC analysis).
Example 3 5.0 g (0.029 mol) of 80 % α,α-dimethyl phenyl carbinol, 0.02 g ammonium bisulfate and 30 g toluene were charged into a 100 mL, three-necked, round- bottomed flask equipped as in Example 2. The mixture was heated at reflux for 2 h at which point no more water was collected in the Dean-Stark separator. GC analysis of the reaction mixture showed a quantitative conversion of α,α-dimethyl phenyl carbinol to α-methylstyrene (3.4 g, 0.029 mol). Example 4 The procedure of Example 3 was used except that 3.0 g (0.018 mol) of 80 % α,α-dimethyl phenyl carbinol, 25 g toluene, and 0.02 g potassium bisulfate were used. 2.1 g (0.018 mol) α-methylstyrene was produced in quantitative yield as determined by GC.
Example 5 5.0 g (0.032 mol) pure α,α-dimethyl 4-fluorophenyl carbinol, 0.05 g potassium bisulfate, and 25 g toluene were charged into a 100 mL, three-necked, round-bottomed flask equipped as in example 2. The mixture was heated at reflux for 73 min at which point no more water was collected in the Dean-Stark water separator. Gas chromatographic analysis of the reaction mixture showed a quantitative conversion of α,α-dimethyl 4-fluorophenyl carbinol to 4-fluoro α- methylstyrene (4.3 g, 0.032 mol).
Example 6 The procedure of Example 5 was used except that 5.0 g (0.032 mol) pure α,α-dimethyl 4-fluorophenyl carbinol, 25 g toluene, and 0.05 g ammonium bisulfate were used. 4.3 g (0.032 mol) 4-fluoro α-methylstyrene were produced in quantitative yield.
Example 7
The procedure of Example 5 was used except that 5.0 g (0.032 mol) pure α,α-dimethyl 4-fluorophenyl carbinol, 0.05 g sodium bisulfate, and 25 g heptane were used. The reaction ran at 102° C for 2 h, producing the product 4-fluoro α- methylstyrene (4.3 g, 0.032 mol) in quantitative yield. Example 8 The procedure of Example 5 was followed except that 0.1 wt % sodium bisulfate (0.02 g) based on the pure α,α-dimethyl 4-fluorophenyl carbinol (20.3 g, 0.130 mol) in 31.5 g toluene were used. The mixture was heated at reflux for 2 h producing 4-fluoro α-methylstyrene (17.6 g, 0.130 mol) in quantitative yield as determined by GC.
Example 9 83.2 g (97 %, 0.51 mol) potassium sulfite and 260 g water were charged into a 1 L, three-necked, round-bottomed flask equipped with a mechanical agitator, water-cooled condenser, heating mantle, and addition funnel. After the aqueous sodium sulfite solution was heated to 100° C, 75.0 g (0.39 mol) cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % α,α- dimethyl phenyl cabinol and 0.5 % acetophenone by GC analysis) were added gradually from the addition funnel over 2 hours at a temperature of about 100° C. The heating was continued at 100 - 120° C for 2 hours yielding a 60.2 g α,α- dimethyl phenyl cabinol mixture (86.8 % α,α-dimethyl phenyl cabinol, 12.6 % cumene, and 0.7 % acetophenone by GC analysis) after phase separation. The organic phase was concentrated to remove cumene by rotary evaporation at 80° C under reduced pressure, leaving 51 g α,α-dimethyl phenyl cabinol in 98.6 % purity as an oily liquid, 96.4 % yield.
50.0 g (0.36 mol) of the α,α-dimethyl phenyl cabinol, 0.5 g potassium bisulfate, and 60 g toluene were charged into a 250 mL, three-necked, round- bottomed flask equipped with a magnetic stirrer, heating mantle, thermometer, water-cooled reflux condenser and Dean-Stark water separator. GC analysis of the reaction mixture showed no significant evidence of α,α-dimethyl phenyl cabinol. The reaction mixture was washed with 5 g water to remove the solid and distilled under reduced pressure using a Vigreux column yielding 41.4 g α,α- methylstyrene in 98.6 % purity, 96 % yield.
Example 10 The procedure of Example 9 was used except that 75.0 g (0.39 mol) cumene oxidation material (78.4 % cumene hydroperoxide, 15.6 % cumene, 5.6 % α,α-dimethyl phenyl carbinol and 0.5 % acetophenone by GC analysis), 64.5 g sodium sulfite, and 105 g water were used in the reduction step and that 50 g of the 98.6 % α,α-dimethyl phenyl carbinol obtained from the concentration by rotary evaporation, 0.5 g sodium bisulfate, and 60 g toluene were used in the dehydration step. The reaction was run at reflux for 2 h at which point GC analysis of the reaction mixture showed no significant evidence of α,α-dimethyl phenyl carbinol. The reaction mixture was washed with 5 g water to remove the solid and distilled under reduced pressure using a Vigreux column yielding 41.5 g α-methylstyrene in 98.4 % purity, 96 % yield.

Claims

What is claimed is:
1. A process for the production of α-methylstyrenes comprising the step of contacting a dimethyl phenyl carbinol of the formula: CH3 ι R - C -CH3 I OH wherein R is an unsubstituted phenyl or phenyl substituted with one or more substituents which substituents are independently G to Cβ alkoxy, G to C6 thioalkyl, cyano, G to C2 dialkylamino, nitro, halogen, C. to C2 haloalkyl, or Ci to
C2 perfluoroalkyl, with an effective amount of an acid salt under conditions suitable to produce an α-methylstyrene product.
2. The process of claim 1 wherein the dimethyl phenyl carbinol is α,α- dimethyl phenyl carbinol.
3. The process of claim 1 wherein the dimethyl phenyl carbinol is in impure form and the process further comprises contacting the impure dimethyl phenyl carbinol comprising a cumene hydroperoxide and α,α-dimethyl phenyl carbinol with an effective amount of a reducing agent prior to contacting the mixture with the acid salt.
4. The process of claim 3 further comprising purifying the impure dimethyl phenyl carbinol after contacting with the reducing agent and prior to contacting with the acid salt to obtain purified α,α-dimethyl phenyl carbinol.
5. The process of claim 1 wherein the acid salt is a salt of an acid having a pKa of about 5 or less and the acid salt counterion is ammonium, sodium, potassium, or lithium.
6. The process of claim 5 wherein the acid salt is sodium bisulfate.
7. A process for the production of α-methylstyrenes comprising the step of contacting α,α-dimethyl phenyl carbinol with an effective amount of an acid salt, wherein the acid salt is a salt of an acid having a pKa of about 5 or less and the acid salt counterion is ammonium, sodium, potassium, or lithium, in the presence of a solvent and under conditions suitable to produce an α-methyl styrene product.
8. A process for the production of α-methylstyrenes comprising the step of contacting α,α-dimethyl phenyl carbinol with sodium bisulfate in an amount of from about 0.1 to about 2.0 weight percent based on the weight of the α,α- dimethyl phenyl carbinol in the presence of a solvent selected from the group consisting of toluene, benzene, hexane, heptane, or the like and under conditions suitable to produce an α-methylstyrene product.
9. The process of claim 8 wherein the α,α-dimethyl phenyl carbinol is in impure form and the process further comprises contacting the impure α,α-dimethyl phenyl carbinol comprising a cumene hydroperoxide and α,α-dimethyl phenyl carbinol with sodium sulfite in an amount of from about 1.0 to about 2.0 equivalents based on equivalents of the cumene hydroperoxide prior to contacting with the acid salt.
10. The process of claim 9 further comprising purifying the impure α,α- dimethyl phenyl carbinol after contacting with the sodium sulfite and prior to contacting with the acid salt to obtain purified α,α-dimethyl phenyl carbinol.
PCT/US1997/022752 1996-12-17 1997-12-10 Process for the production of alpha methylstyrenes WO1998027030A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6984761B2 (en) 2002-12-16 2006-01-10 Exxonmobil Chemical Patents Inc. Co-production of phenol, acetone, α-methylstyrene and propylene oxide, and catalyst therefor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1239185A (en) * 1969-01-28 1971-07-14

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1239185A (en) * 1969-01-28 1971-07-14

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6984761B2 (en) 2002-12-16 2006-01-10 Exxonmobil Chemical Patents Inc. Co-production of phenol, acetone, α-methylstyrene and propylene oxide, and catalyst therefor
KR101084379B1 (en) 2002-12-16 2011-11-18 엑손모빌 케미칼 패턴츠 인코포레이티드 Simultaneous preparation of phenol, acetone, α-methylstyrene and propylene oxide, and catalyst for the same

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