I. The Background of the Invention 1,1-Dihalo-l-cyclopropylethanes are used to prepare 1-cyclopropylethyne. The latter is a known intermediate, which may be used to prepare many organic compounds. For example, 1-cyclopropylethyne is a critical ingredient to prepare a highly potent HIV reverse transcription inhibitor. See PCT application WO 96/37457 to Thompson and others.

1-Cyclopropylethyne is, in one approach, formed by reacting a 1,1-dihalo-l-cyclopropylethane (DCCP) with one or more strong bases, such as potassium hydroxide (see Hanack and Bässler, J. Amer. Chem. Soc. 91,2117 (1969)) or potassium t-butoxide (Salaun, J. Org. Chem.

41, No. 7,1237 (1976)). It is desirable to start with reasonably pure 1,1-dihalo-1-cyclopropylethane to avoid further processing and complicated purification methods.

One source of 1,1-dihalo-l-cyclopropylethane is the reaction of cyclopropyl methyl ketone with phosphorus pentachloride (PC15) (Hanack and Bassler, J.

Amer Chem. Soc 91,2117 (1969)), which produces phosphorus oxyhalides as co-products. Previous methods for the removal of the phosphorus oxyhalides result in significant decomposition of DCCP to ring-opened

dihalopentenes. As a result, what is needed is a method to remove phosphorus oxyhalide and reduce decomposition of 1,1-dihalo-1-cyclopropylethane. This invention addresses that need.

II. The Summary of the Invention In one aspect, this invention is a method to reduce the amount of phosphorus oxyhalide in a mixture containing 1,1-dihalo-1-cyclopropylethane, an organic solvent, and phosphorus oxyhalide by contacting the mixture with an alcohol and an aqueous amine.

In another aspect, this invention is a method to reduce the amount of phosphorus oxyhalide in a mixture containing 1,1-dihalo-l-cyclopropylethane, an organic solvent, and phosphorus oxyhalide by contacting the mixture with an alcohol and an epoxide.

In still another aspect, this invention is a method to reduce the amount of phosphorus oxyhalide in a mixture containing 1,1-dihalo-1-cyclopropylethane, an organic solvent, and phosphorus oxyhalide by contacting the mixture with an alcohol and a nonaqueous amine.

And in another aspect, this invention is a method to remove dihalogenated pentenes from a mixture containing 1,1-dihalo-1-cyclopropylethane and dihalogenated pentenes by contacting the mixture with a halogen under conditions sufficient to convert a substantial portion of the dihalogenated pentenes into polyhalogenated pentanes and distilling the mixture to recover the 1,1-dihalo-1-cyclopropylethane.

An object of this invention is to remove phosphorus oxyhalide and/or dihalogenated pentene impurities from 1,1-dihalo-1-cyclopropylethane.

A feature of this invention is that these impurities are removed without substantially affecting the 1,1-dihalo-1-cyclopropylethane.

An advantage of this invention is that it is economical to use in a synthesis that starts with cyclopropyl methyl ketone and ends with 1- cyclopropylethyne.

III. The Description of the Preferred Embodiments Specific language is used in the following description and examples to publicly disclose the invention and to convey its principles to others. No limits on the breadth of the patent rights based simply on using specific language are intended. Also included are any alterations and modifications to our descriptions that should normally occur to one of average skill in this technology.

1,1-Dihalo-l-cyclopropylethanes are frequently formed by reacting cyclopropyl methyl ketone with slurry of solvent and phosphorus halide. Preferable solvents include C5 to C20 hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons or aromatic hydrocarbons. The ketone is added to the slurry and the resulting mixture is maintained between minus 10°C and 70°C until the reaction is complete. The reaction also produces phosphorus oxyhalide co-products and dihalogenated pentenes.

One embodiment of this invention is a method to remove the phosphorus oxyhalide without substantially affecting the 1,1-dihalo-1-cyclopropylethane. The method begins by leaving the 1,1-dihalo-1- cyclopropylethane in the organic solvent in which it is produced, but if necessary, one could also use fresh solvent, preferably a CS to C20 hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, preferably a Ci to C5 halogenated species ; or a halogenated aromatic hydrocarbon.

The 1,1-dihalo-1-cyclopropylethane and solvent are then combined with an aqueous amine and an alcohol.

The alcohol is preferably dihydric, but a monohydric alcohol may also be used. The preferred amines are alkanolamines of which the most preferred are ethanolamine, propanolamine, and butanolamine. The amine concentration before addition is preferably from about 20-wt% to about 60-wt%. The most preferred dihydric alcohols are ethylene glycol, propylene glycol, and butylene glycol. The alcohol and the aqueous amine can be added simultaneously or separately, and preferably all the reactants are maintained between about minus 20°C to about 10°C from the time they are combined until the reaction is complete, (i. e. the oxyhalide is removed).

The reaction leaves a biphasic mixture, and most of the 1,1-dihalo-1-cyclopropylethane is contained in the organic solvent phase. The 1,1-dihalo-1- cyclopropylethane may be removed using well-known techniques such as draining the aqueous phase from the

product mixture and distilling to recover 1,1-dihalo-1- cycloproylethane from the mixture.

Without limiting the scope of the invention, it is believed that a variety of compounds are formed when the phosphorus oxyhalide reacts with the alcohol and the aqueous amine. For example, it is conceivable that the reaction may produce phosphates, phosphoramides, amine salts, as well as several phosphorus-halide species. These compounds are then either removed during the distillation of the 1,1-dihalo-1- cyclopropylethane or depart with the aqueous phase.

A second embodiment of this invention is another method to remove the phosphorus oxyhalide without substantially affecting the 1,1-dihalo-1- cyclopropylethane. This second method also begins by leaving the 1,1-dihalo-1-cyclopropylethane in the organic solvent in which it is produced, but if necessary, one may also use fresh solvent, preferably a C5 to C20 hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, preferably a C1 to C5 halogenated species; or a halogenated aromatic hydrocarbon.

The 1,1-dihalo-1-cyclopropylethane and solvent are then combined with an epoxide and an alcohol that is preferably mono-or dihydric. The preferred epoxides are ethylene oxide, propylene oxide, butylene oxide, and styrene oxide. The most preferred monohydric alcohols are methanol, ethanol, propanol, and butanol.

And the most preferred dihydric alcohols are ethylene glycol, propylene glycol, and butylene glycol. The

alcohol and the epoxide can be added simultaneously or separately, and preferably all the reactants are maintained between about minus 10°C and about 50°C from the time they are combined until the reaction is complete.

The reaction leaves a biphasic mixture, and most of the 1,1-dihalo-1-cyclopropylethane is contained in the organic solvent phase. The 1,1-dihalo-1- cyclopropylethane may be removed using well-known techniques such as draining the alcohol phase from the product mixture and distilling to recover the 1,1- dihalo-1-cycloproprylethane from the mixture.

Additionally, the alcohol phase may be washed with fresh solvent and the washing solvent added to the organic solvent phase prior to distillation.

Without limiting the scope of the invention, it is believed that a variety of compounds are formed when the phosphorus oxyhalide reacts with the alcohol and the epoxide. For example, it is conceivable that the reaction may produce alkyl phosphate esters, haloalkanols, and possibly some phosphorus-halide species. These compounds are then either removed during the distillation of the 1,1-dihalo-1- cyclopropylethane or depart with the alcohol.

A third embodiment of this invention is yet another method to remove the phosphorus oxyhalide without substantially affecting the 1,1-dihalo-1- cyclopropylethane. This third method also begins by leaving the 1,1-dihalo-1-cyclopropylethane in the organic solvent in which it is produced, but if

necessary, one may also use fresh solvent, preferably a C5 to C16 hydrocarbon, an aromatic hydrocarbon, a <BR> <BR> <BR> <BR> halogenated hydrocarbon preferably a Clto C5 halogenated species; or a halogenated aromatic hydrocarbon.

The 1,1-dihalo-l-cyclopropylethane and solvent are then combined with an amine, which is preferably tertiary, and an alcohol, which is preferably mono-or dihydric. The most preferable tertiary amines are trimethylamine, triethylamine, tri-n-propylamine, tri- n-butylamine, and dimethyl-sec-butylamine. The most preferred monohydric alcohols are methanol, ethanol, propanol, and butanol. And the most preferred dihydric alcohols are ethylene glycol, propylene glycol, and butylene glycol.

The alcohol and the amine can be added simultaneously or separately, and preferably all the reactants are maintained between about minus 5°C to about 30°C from the time they are combined until the reaction is complete. Preferably, the product slurry is then filtered to remove any solids, such as amine salts, that may have formed during the reaction. The 1,1-dihalo-1-cyclopropylethane may then be removed using well-known techniques such as distilling the filtrate liquors that remain.

Without limiting the scope of the invention, it is believed that a variety of compounds are formed when the phosphorus oxyhalide reacts with the alcohol and the amine. For example, it is conceivable that the reaction may produce alkylamine hydrohalide salts and alkylphosphate esters. These compounds are then either

filtered out or removed during the distillation of the 1,1-dihalo-1-cyclopropylethane.

A related embodiment of this invention is a method to remove dihalogenated pentenes that also may be present in the 1,1-dihalo-1-cyclopropylethane by converting them into tetrahalogenated pentanes. The method begins by contacting the 1,1-dihalo-1- cyclopropylethane with a halogen, preferably chlorine, bromine, or bromine chloride. The reactants are preferably maintained between about minus 10°C to about 60°C until the reaction is complete, which is preferably when the level of dihalogenated pentenes is less than 5-wt% or more preferably less than 1-wt%. The 1,1- dihalo-1-cyclopropylethane may then be separated from the tetrahalogenated pentanes using well-known techniques such as distilling the product mixture at reduced pressure. This may be done with or without a solvent.

This halogenation is far from intuitive. 1,1- Dihalo-1-cyclopropylethanes are known to be highly sensitive to acidic conditions. Accordingly, one might expect that the halogen would create hydrochloric or hydrobromic acid, which would attack the 1,1-dihalo-1- cyclopropylethane. But this does not occur to any great degree, and especially does not occur when the halogenation is performed in the suggested temperature range or lower.

IV. The Examples Example 1 First, a 100-gallon GLS (glass-lined steel) reactor was charged with 280.0 lb. of Norpar 130, which is a C12 to C14 linear hydrocarbon solvent and 300 lb. of solid phosphorus pentachloride. The resulting PC15/solvent slurry was then cooled to ~0°C. Next, 120.6 lb. of cyclopropyl methyl ketone (CPMK) was added to the slurry while maintaining the internal reactor temperature below 20°C. After the CPMK addition was complete, the mixture was allowed to warm with mild heating to-65°C. The mixture was held at-65°C for 0.5 hr during which time the slurry became clear yellow. At this point, the solution was cooled to ambient temperature. The crude product contained about 25 to 35-wt% phosphorus oxychloride; however, gas chromatographic (GC) analysis of the mixture also indicated complete conversion of the CPMK to a mixture of 1,1-dichloro-1-cyclopropylethane (DCCP) and E/Z isomers of 2,5-dichloropent-2-ene (DCP). The DCCP to DCP ratio was-86: 14 by weight, and 149.3 lb. of DCCP was present.

The crude product was then transferred to a 200 gallon GLS reactor and cooled to-10°C. Thereafter, 179.0 lb. of ethylene glycol was added to the mixture while maintaining the internal pot temperature below 0°C. Next, 218.0 lb. of a 40: 60 wt./wt. mixture of ethanolamine and water was added to the reactor while maintaining the internal pot temperature below 0°C.

After the addition, the mixture was agitated for 0.5 hr

and allowed to settle without agitation for 1.0 hr while maintaining the internal temperature below 0°C.

The lower aqueous phase was drawn off to a neutralization vessel, and the organic phase was transferred to a 100-gallon distillation vessel.

The crude product mixture was flash distilled at reduced pressure (-10 mm Hg) to an overhead temperature of 45°C, and a mixture of 1,1-dichloro-1- cyclopropylethane and E/Z 2,5-dichloropent-2-ene was recovered. DCCP contained in the recovered distillate was 109.5 lb. The DCCP to DCP ratio in the distillate was 67: 33 by weight, and only a negligible amount of phosphorus oxychloride was present.

Example 2 The preparation of DCCP was repeated according the method described in Example 1, however, chlorobenzene was used as the reaction solvent. The crude DCCP and chlorobenzene were then transferred to a 200 gallon GLS reactor and the procedure described in Example 1 was repeated using a mixture of butanolamine and water for the aqueous amine and butylene glycol for the alcohol.

The crude product mixture was then flash distilled at reduced pressure, and a mixture of 1,1-dichloro-1- cyclopropylethane and E/Z 2,5-dichloropent-2-ene was recovered.

Example 3 The preparation of DCCP was repeated according the' method described in Example 1, however, chlorobutane

was used as the reaction solvent. The crude DCCP and chlorobutane were then transferred to a 200 gallon GLS reactor and the procedure described in Example 1 was repeated using a mixture of propanolamine and water for the aqueous amine and butanol for the alcohol. The crude product mixture was then flash distilled at reduced pressure, and a mixture of 1,1-dichloro-1- cyclopropylethane and E/Z 2,5-dichloropent-2-ene was recovered.

Example 4 The reaction to synthesize DCCP shown in Example 1 was repeated with the same temperature parameters using 804.4 g of PC15 in 774.0 g of Norpar-13@ solvent in a 3 liter reactor and 300.0 g of CPMK. The resulting solution contained about 25 to 35-wt% phosphorus oxychloride; however, gas chromatography revealed a 76% yield of DCCP with a DCCP to DCP ratio of about-87: 13 DCCP to DCP.

The crude product mixture was then added to a pre- chilled (0°C) solution of MeOH (343 g), propylene oxide (642 g), and ethylene glycol (664 g) with stirring and while maintaining the internal temperature <20°C with ice bath cooling. The addition required-8hrs, after which the bi-phasic mixture was stirred for 0.5 hr and then allowed to separate for 0.5 hr. The lower glycol layer (2429.7 g) was separated from the upper Norpar@ layer (1008.0 g). The glycol layer was washed with Norpar-13@ (3 x 300 g). The extracts were combined with the original Norpar@ layer and distilled through a 5-tray Oldershaw column collecting material at ~55°C @

50 mm Hg. The distillate exhibited a DCCP/DCP ratio of 92: 8. The recovery of DCCP from the dichlorination reaction mixture totaled 332.8 g with only a negligible amount of phosphorus oxychloride.

Example 5 The preparation of DCCP was repeated according the method described in Example 1, however, chlorobenzene was used as the reaction solvent. The crude DCCP and chlorobenzene were then treated with alcohol and epoxide as described in Example 4, however, propanol was used for the alcohol and styrene oxide was used for the epoxide. The crude product mixture was then distilled, and a mixture of 1,1-dichloro-1- cyclopropylethane and 2,5-dichloropent-2-ene was recovered.

Example 6 The preparation of DCCP was repeated according the method described in Example 1, however, chlorobutanol was used as the reaction solvent. The crude DCCP and chlorobenzene were then treated with alcohol and epoxide as described in Example 4, however, butanol was used for the alcohol and ethylene oxide was used for the epoxide. The crude product mixture was then distilled, and a mixture of 1,1-dichloro-1- cyclopropylethane and 2,5-dichloropent-2-ene was recovered.

Example 7 CPMK (50.0 g) was again dichlorinated as previously described in Example 1 using 129.3 g of PC15 ;

however, instead of Norpar 13@, the PC15 was suspended in 392.3 g of o-dichlorobenzene (ODCB). The post- reaction solution exhibited a DCCP: DCP ratio of 87: 13 and about 25 to 35-wt% phosphorus oxychloride.

Thereafter, 186.5 g of triethylamine in 109.0 g of n- propanol was then added to the crude product over 2 hr while maintaining the internal temperature <25°C. The mixture was then heated to 50°C, which caused an exothermic reaction to increase the internal temperature to 62°C. After the exotherm subsided, the slurry was held at 50°C for 5.5 hr to complete the consumption of POC13. The suspension was cooled to room temperature and then filtered to remove salts. The filter cake was washed with ODCB. The filtrate and washes were combined and distilled through a 10 tray Oldershaw column using a 3: 1 reflux ratio collecting the fraction exhibiting a 70-82°C overhead temperature.

A total of 35.8 g of DCCP was recovered from the distillation with only negligible amounts of phosphorus oxychloride.

Example 8 DCCP was again prepared in ODCB as described in Example 7. Thereafter the crude DCCP was combined with an amine and alcohol as described in Example 7. But in place of triethylamine and n-propanol, tri-n-butylamine and butylene glycol were used. The product slurry was then filtered and the filtrate liquors were distilled to recover the DCCP.

Example 9 A mixture (775.6 lbs.) containing-67% 1,1-

dichloro-1-cyclopropylethane and-33% 2,5-dichloropent- 2-ene was charged to a 100 gallon GLS reactor. The mixture was cooled to <10°C. A mixture of chlorine and nitrogen gas was charged through a sub-surface sparge tube into the well-agitated solution. The addition was mildly exothermic and controlled by moderating the chlorine addition rate and maintaining cooling on the reactor jacket during the addition. The mixture was maintained below 25°C during the chlorine addition and the addition was stopped after 143.7 lbs. of chlorine (1.1 equivalents based on 2,5-dichloropent-2-ene) were added. The mixture was analyzed to determine the DCP content by gas chromatograhy. The target DCCP to DCP ratio of >100: 1 was confirmed by the analysis.

Nitrogen was then sparged through the solution for 0.5 hr to remove the residual chlorine. The clear solution was transferred to a 100 gallon GLS distillation vessel and flash distilled at reduced pressure (-10 mm Hg) while collecting the distillate up to an overhead temperature of-55°C. Analysis of the distillate indicated 498.9 lbs. of DCCP were recovered ; equivalent to a 96% recovered yield of the DCCP initially charged to the chlorination reaction. The distillate exhibited a DCCP: DCP ratio of >100: 1 after chlorination and distillation.

Example 10 792.6 lbs. of a mixture containing 67% 1,1- dichloro-1-cyclopropylethane and 33% 2,5-dichloropent-- 2-ene were charged in a 100 gallon GLS reactor and the

mixture was cooled to <10°C. Bromine was charged through a dip tube into the well-agitated solution.

Furthermore, an epoxide (ERL-4221, Union Carbide) was added at this scale to reduce overall acidity. This would not be beneficial if chlorinating, instead of bromoninating. The addition was mildly exothermic and controlled by moderating the bromine addition rate and maintaining cooling on the reactor jacket during the addition. The mixture was maintained below 25°C during the bromine addition. The addition was stopped after 330 lbs. of bromine (1.1 equivalents based on 2,5- dichloropent-2-ene) were added. The reaction was readily monitored by observing a change in the color of the solution from dark red to very pale yellow indicating bromine uptake. The mixture was analyzed to determine the DCP content by gas chromatography. The target DCCP to DCP ratio of >95: 1 was confirmed by the analysis. Excess bromine was consumed by the addition of a small quantity of a C14 to C16 long chain olefin (e. g. Neodene 16@ (Shell)). Nitrogen was then sparged through the solution for 0.5 hr. The clear solution was transferred to a 100 gallon GLS distillation vessel and flash distilled at reduced pressure (-10mm Hg) collecting the distillate up to an overhead temperature of-55°C. Analysis of the distillate indicated 472.6 lbs. of DCCP were recovered; equivalent to an 89% recovery of the DCCP initially charged to the chlorination reaction. The distillate exhibited a DCCP: DCP ratio of >95: 1 after bromination and distillation.

V. The Claims While the invention has been illustrated and described in detail, this is to be considered as illustrative and not restrictive of the patent rights.

The reader should understand that only the preferred embodiments have been presented and all changes and modifications that come within the spirit of the invention are included if the following claims or the legal equivalent of these claims describes them.