CA1049040A - 7.7-dichlorobicyclo-(3.2.0)-hept-2-en-6-one - Google Patents
7.7-dichlorobicyclo-(3.2.0)-hept-2-en-6-oneInfo
- Publication number
- CA1049040A CA1049040A CA75229121A CA229121A CA1049040A CA 1049040 A CA1049040 A CA 1049040A CA 75229121 A CA75229121 A CA 75229121A CA 229121 A CA229121 A CA 229121A CA 1049040 A CA1049040 A CA 1049040A
- Authority
- CA
- Canada
- Prior art keywords
- cyclopentadiene
- process according
- inert solvent
- dichloroacetyl chloride
- tertiary amine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
- C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
- C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
- C07C45/69—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by addition to carbon-to-carbon double or triple bonds
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
7.7-DICHLOROBICYCLO-[3.2.0]-HEPT-2-EN-6-ONE
Abstract of the disclosure:
7.7-Dichlorobicyclo-[3.2.0]-hept-2-en-6-one is prepared from cyclopentadiene and dichloroketene, intermedially obtain-ed from dichloroacetyl chloride and a tertiary amine, by adding a mixture of cyclopentadiene and a tertiary amine at a tempe-rature of about 20 to 120°C to a mixture of an inert solvent and dichloroacetaldehyde or by adding a mixture of cyclopenta-diene and dichloroacetaldehyde at a temperature of about 20 to 120°C to a mixture of an inert solvent and a tertiary amine.
7.7-Dichlorobicyclo-[3.2.0]-hept-2-en-6-one is a valubale intermediate for syntheses of tropolone and of pesticides.
Abstract of the disclosure:
7.7-Dichlorobicyclo-[3.2.0]-hept-2-en-6-one is prepared from cyclopentadiene and dichloroketene, intermedially obtain-ed from dichloroacetyl chloride and a tertiary amine, by adding a mixture of cyclopentadiene and a tertiary amine at a tempe-rature of about 20 to 120°C to a mixture of an inert solvent and dichloroacetaldehyde or by adding a mixture of cyclopenta-diene and dichloroacetaldehyde at a temperature of about 20 to 120°C to a mixture of an inert solvent and a tertiary amine.
7.7-Dichlorobicyclo-[3.2.0]-hept-2-en-6-one is a valubale intermediate for syntheses of tropolone and of pesticides.
Description
~Og9040 7.7-Dichlorobicyclo- [3.2.0] -hept-2-en-6-one (subsequently called "the compound") is a valuable intermediate, especially for syntheses of tropolone and of pesticides (cf. Belgian Patent 706,795)o It is prepared according to a known process (Tetrahedron, 27 (1971), pages 615 - 633) by reacting cyclopentadiene with dichloroketene according to the following equation:
~r C - Clz ~ ~ Cl This reaction is difficult to handle because both reactants are unstable compounds. Cyclopentadiene can be stored only at low temperatures because of its pronounced dimerization tendency. Dichloroketene is still unknown as an isolated substance and is obtainable only in dilute solution;
it must be prepared in situ~ conveniently by dehydrochlorination of dichloroacetyl chloride by means of tertiary amines.
In the known processes for preparing the compound, cyclopentadiene and one of the components of the dichloroketene formation, i.e. either dichloroacetyl chloride or tertiary amine, are introduced into the reaction ve99el in high dilution with inert solvent and the other component of the dichloroketene formation is added dropwise. The reaation temperature is not allowed to exceed 50 C. The molar ratio of cyclopentadiene to dichloroketene is at least about 3:1, i.e. a considerable excess of cyclopentadiene is always used.
This process is technically expensive and wasteful because of the large quantities of solvent as well as the excess
~r C - Clz ~ ~ Cl This reaction is difficult to handle because both reactants are unstable compounds. Cyclopentadiene can be stored only at low temperatures because of its pronounced dimerization tendency. Dichloroketene is still unknown as an isolated substance and is obtainable only in dilute solution;
it must be prepared in situ~ conveniently by dehydrochlorination of dichloroacetyl chloride by means of tertiary amines.
In the known processes for preparing the compound, cyclopentadiene and one of the components of the dichloroketene formation, i.e. either dichloroacetyl chloride or tertiary amine, are introduced into the reaction ve99el in high dilution with inert solvent and the other component of the dichloroketene formation is added dropwise. The reaation temperature is not allowed to exceed 50 C. The molar ratio of cyclopentadiene to dichloroketene is at least about 3:1, i.e. a considerable excess of cyclopentadiene is always used.
This process is technically expensive and wasteful because of the large quantities of solvent as well as the excess
- 2 -, of cyclopentadiene required.
Moreover the isolation of the reaction product is difficult, since bicycloheptenones, especially halogenated, are thermally unstable.
Attempts to isolate or to purify larger quantities of said product by conven tional distillation methods frequently result in explosive decompositions, e9pecially if impurities are present.
It is therefore an object of the present invention to prepare the compound in a more economical manner with a higher space-time yield and to obtain a product of higher purity without the danger of decomposition.
According to the present invention there is provided a process for preparing 7.7-dichlorobicyclo- [3.~.] -hept-2-en-6-one by reaction in an inert solvent between cyclopentadiene and dichloroketene prepared in situ by reaction between dichloroacetyl chloride and a tertiary amine, wherein one of the dichloroacetyl chloride and tertiary amine is dissolved in the inert solvent and the other of the dichloroacetyl chloride and tertiary amine is added with the cyclopentadiene to the inert solvent~ the process being carried out at a temperature between about 20 and about 120&, preferably about 40 to about 100 C. The reaction mixture is then worked up in usual manner.
Both components of the dichloroketene preparation are advantageously used in about stoichiometric quantities and cyclopentadiene is used in a molar excess of about 5 to 25%.
The reaction mixture is advantageously worked up by steam distillation.
In contrast to the known process where cyclopentadiene together ; with one of the components of the dichloroketene :
~ - 3 -.
. ~.
:
formation is given first into the reaction vessel only one component of the dichloroketene preparation is initially present. This saves considerable quantities of solvent required in the known process because of the instabi-lity of cyclopentadiene. Only a minimum of solvent is necessary to assure stirring of the reaction mixture, which in the course of the reaction be-comes increasingly difficult because of the precipitation of aminochloro-hydrate. The preferred amount of solvent generally is in the range of about 2 to 4 parts by volume per part by weight of cyclopentadiene.
A further important improvement of the process according to the in-vention over the state of the art is that a large excess of cyclopentadiene can be dispensed with. It is not required, consequently, to recover non-reacted cyclopentadiene in an expensive and wasteful manner.
Since cyclopentadiene is only added later in the process of the in-vention, it is possible to maintain a higher reaction temperature than in the known process and thus to obtain a higher reaction velocity. Surpris-ingly no or practically no di-or polymerization of the cyclopentadiene occurs even at temperatures around or above 100C, since the reaction of cyclo-pentadiene with dichloroketene proceeds faster that the polymerization re-action.
The yield of pure substance in the process according to the in-vention is in the same range as in the known process (about 70 to 80%).
The space-time yield, however, is moreover considerably improved because of the advantages mentioned before.
External heating is not required in the process of the invention.
The desired reaction temperature adjusts itself according to the input velocity of the mixture of cyclopentadiene and second dichloroketene-com-ponent as a consequence of the reaction heat and may be maintained at the desired level optionally by reflux or exterior cooling. It is likewise possible to start feeding at a higher temperature, optionally at the reflux temperature of the mixture firstly introduced into the reaction vessel, which may be advantageous in some cases.
All liquids inert with regard to the reactants may be used as solvents for the first component of dichloroketene formation. Especially useful are aliphatic and aromatic hydrocarbons having boiling points preferably below 150C, particularly in the range of from 50 to 100C, such as (C6 to C10) paraffines, cyclohexane, benzene, toluene, xylene, chlorinated aromatic agents such as chlorobenzene, dichlorobenzene, but also ethers such as di-isopropyl ethers, tetrahydrofurane etc..
The reaction mixture can be worked up in known manner, i.e. by vacuum distillation, or preferably by steam distillation with normally heated or overheated steam, whereby first the solvent and optionally a small excess of dicyclopentadiene and then the bicycloheptenone is distilled of. The com-pound obtained in this way is very pure and contains only traces of substances favouring decomposition of the product, especially at higher temperatures.
The yields of the product obtained in the distillation and in the working up are higher than that of the product only isolated by vacuum distillation.
The improved thermal stability permits to obtain higher reaction temperatures in further reactions. It is moreover quite surprising that the steam dis-tillation may be carried out with the strongly acidic reaction mixture, the acid reaction being caused by aminohydrochloride, although the bicyclohepte-none hydrolizes in weakly alcaline solution tof a pH of 9) at high tempera-tures and is converted into tropolone by weak acidic medium.
The following examples illustrate the invention:
E X A M P L E 1:
295 g (2 moles) of dichloroacetyl chloride in 800 ml of toluene were introduced into a 2 liter flask and, beginning at room temperatures, a cooled mixture of 203 g of triethylamine (2 moles) and 165 g of cyclopenta-diene (2.5 moles) was added thereto. During the time of addition of 40 minutes the temperature rose to about 90C and was maintained at this level for 30 minutes after the addition had been stopped. The components of the mixture were then distilled off with overheated steam, until distillation was 3Q fini$hed. 258 g of pure 7.7-dichloro-bicy~1O-[3.2.0]-hept-2-en-6-one (73%
of the theory) were obtained by vacuum distillation from the toluene phase of the distillate.
~049040 The aqueous distillation residue was rendered alkaline with sodium hydroxide solution and triethylamine was stem-distilled off.
E X A M P L E 2:
135 kg of technical heptane and 69 kg of triethylamine were introduced into a 500 liter vessel. A mixture of 100 kg of dichloroacetyl chloride and 52 kg of cyclopentadiene (of 95%) obtained at a temperature of -10C was added within 45 minutes, whereby the inner temperature rose to 86C and the mixture began to reflux. After having continued stirring for lO minutes at 90C, heptane, some dicyclopentadiene and the reaction product were steam-distilled. After separation of the phases the organic phase was dehydrated by slightly distilling it and 7.7-dichlorobicylco-[3.2.01-hept-2-en-6-one was obtained therefrom by fractional distillation in a yield of 95 kg ~80% of the theory).
Moreover the isolation of the reaction product is difficult, since bicycloheptenones, especially halogenated, are thermally unstable.
Attempts to isolate or to purify larger quantities of said product by conven tional distillation methods frequently result in explosive decompositions, e9pecially if impurities are present.
It is therefore an object of the present invention to prepare the compound in a more economical manner with a higher space-time yield and to obtain a product of higher purity without the danger of decomposition.
According to the present invention there is provided a process for preparing 7.7-dichlorobicyclo- [3.~.] -hept-2-en-6-one by reaction in an inert solvent between cyclopentadiene and dichloroketene prepared in situ by reaction between dichloroacetyl chloride and a tertiary amine, wherein one of the dichloroacetyl chloride and tertiary amine is dissolved in the inert solvent and the other of the dichloroacetyl chloride and tertiary amine is added with the cyclopentadiene to the inert solvent~ the process being carried out at a temperature between about 20 and about 120&, preferably about 40 to about 100 C. The reaction mixture is then worked up in usual manner.
Both components of the dichloroketene preparation are advantageously used in about stoichiometric quantities and cyclopentadiene is used in a molar excess of about 5 to 25%.
The reaction mixture is advantageously worked up by steam distillation.
In contrast to the known process where cyclopentadiene together ; with one of the components of the dichloroketene :
~ - 3 -.
. ~.
:
formation is given first into the reaction vessel only one component of the dichloroketene preparation is initially present. This saves considerable quantities of solvent required in the known process because of the instabi-lity of cyclopentadiene. Only a minimum of solvent is necessary to assure stirring of the reaction mixture, which in the course of the reaction be-comes increasingly difficult because of the precipitation of aminochloro-hydrate. The preferred amount of solvent generally is in the range of about 2 to 4 parts by volume per part by weight of cyclopentadiene.
A further important improvement of the process according to the in-vention over the state of the art is that a large excess of cyclopentadiene can be dispensed with. It is not required, consequently, to recover non-reacted cyclopentadiene in an expensive and wasteful manner.
Since cyclopentadiene is only added later in the process of the in-vention, it is possible to maintain a higher reaction temperature than in the known process and thus to obtain a higher reaction velocity. Surpris-ingly no or practically no di-or polymerization of the cyclopentadiene occurs even at temperatures around or above 100C, since the reaction of cyclo-pentadiene with dichloroketene proceeds faster that the polymerization re-action.
The yield of pure substance in the process according to the in-vention is in the same range as in the known process (about 70 to 80%).
The space-time yield, however, is moreover considerably improved because of the advantages mentioned before.
External heating is not required in the process of the invention.
The desired reaction temperature adjusts itself according to the input velocity of the mixture of cyclopentadiene and second dichloroketene-com-ponent as a consequence of the reaction heat and may be maintained at the desired level optionally by reflux or exterior cooling. It is likewise possible to start feeding at a higher temperature, optionally at the reflux temperature of the mixture firstly introduced into the reaction vessel, which may be advantageous in some cases.
All liquids inert with regard to the reactants may be used as solvents for the first component of dichloroketene formation. Especially useful are aliphatic and aromatic hydrocarbons having boiling points preferably below 150C, particularly in the range of from 50 to 100C, such as (C6 to C10) paraffines, cyclohexane, benzene, toluene, xylene, chlorinated aromatic agents such as chlorobenzene, dichlorobenzene, but also ethers such as di-isopropyl ethers, tetrahydrofurane etc..
The reaction mixture can be worked up in known manner, i.e. by vacuum distillation, or preferably by steam distillation with normally heated or overheated steam, whereby first the solvent and optionally a small excess of dicyclopentadiene and then the bicycloheptenone is distilled of. The com-pound obtained in this way is very pure and contains only traces of substances favouring decomposition of the product, especially at higher temperatures.
The yields of the product obtained in the distillation and in the working up are higher than that of the product only isolated by vacuum distillation.
The improved thermal stability permits to obtain higher reaction temperatures in further reactions. It is moreover quite surprising that the steam dis-tillation may be carried out with the strongly acidic reaction mixture, the acid reaction being caused by aminohydrochloride, although the bicyclohepte-none hydrolizes in weakly alcaline solution tof a pH of 9) at high tempera-tures and is converted into tropolone by weak acidic medium.
The following examples illustrate the invention:
E X A M P L E 1:
295 g (2 moles) of dichloroacetyl chloride in 800 ml of toluene were introduced into a 2 liter flask and, beginning at room temperatures, a cooled mixture of 203 g of triethylamine (2 moles) and 165 g of cyclopenta-diene (2.5 moles) was added thereto. During the time of addition of 40 minutes the temperature rose to about 90C and was maintained at this level for 30 minutes after the addition had been stopped. The components of the mixture were then distilled off with overheated steam, until distillation was 3Q fini$hed. 258 g of pure 7.7-dichloro-bicy~1O-[3.2.0]-hept-2-en-6-one (73%
of the theory) were obtained by vacuum distillation from the toluene phase of the distillate.
~049040 The aqueous distillation residue was rendered alkaline with sodium hydroxide solution and triethylamine was stem-distilled off.
E X A M P L E 2:
135 kg of technical heptane and 69 kg of triethylamine were introduced into a 500 liter vessel. A mixture of 100 kg of dichloroacetyl chloride and 52 kg of cyclopentadiene (of 95%) obtained at a temperature of -10C was added within 45 minutes, whereby the inner temperature rose to 86C and the mixture began to reflux. After having continued stirring for lO minutes at 90C, heptane, some dicyclopentadiene and the reaction product were steam-distilled. After separation of the phases the organic phase was dehydrated by slightly distilling it and 7.7-dichlorobicylco-[3.2.01-hept-2-en-6-one was obtained therefrom by fractional distillation in a yield of 95 kg ~80% of the theory).
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing 7.7-dichlorobicyclo- [3.2.] -hept-2-en-6-one by reaction in an inert solvent between cyclopentadiene and dichloroketene prepared in situ by reaction between dichloroacetyl chloride and a tertiary amine, wherein one of the dichloroacetyl chloride and tertiary amine is dissolved in the inert solvent and the other of the dichloroacetyl chloride and tertiary amine is added with the cyclopentadiene to the inert solvent, the process being carried out at a temperature between about 20 and about 120°C.
2. A process according to claim 1 wherein the cyclopentadiene is used in molar excess over the dichloroketene.
3. A process according to claim 2 wherein the cyclopentadiene is used in a molar excess of about 5 to 25%.
4. A process according to claim 1 wherein the dichloroacetyl chloride and tertiary amine used to form the dichloroketene are used in substantially equimolar amounts.
5. A process according to claim 1 wherein the inert solvent is an aliphatic or aromatic hydrocarbon having a boiling point below 150°C.
6. A process according to claim 1 wherein the inert solvent is a C6 to C10 paraffin, cyclohexane, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, diisopropyl ether or tetrahydrofurane.
7. A process according to claim 1, 5 or 6 wherein the amount of inert solvent used is in the range of from 2 to 4 parts by volume per part by weight of cyclopentadiene.
8. A process according to claim 1 wherein the product is worked up by steam distillation.
9. A process according to claim 1 wherein dichloroacetyl chloride is dissolved in toluene and a mixture of triethylamine and cyclopentadiene is added thereto.
10. A process according to claim 1 wherein triethylamine is dissolved in heptane and a mixture of dichloroacetyl chloride and cyclopentadiene is added thereto.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2428410A DE2428410C2 (en) | 1974-06-12 | 1974-06-12 | Method of making 7 7-Dichlorbicyclo square bracket on 3.2.0 square bracket to hept-2-en-6-one |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1049040A true CA1049040A (en) | 1979-02-20 |
Family
ID=5917965
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA75229121A Expired CA1049040A (en) | 1974-06-12 | 1975-06-11 | 7.7-dichlorobicyclo-(3.2.0)-hept-2-en-6-one |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS518253A (en) |
| AT (1) | AT337665B (en) |
| BE (1) | BE830184A (en) |
| CA (1) | CA1049040A (en) |
| CH (1) | CH613179A5 (en) |
| DE (1) | DE2428410C2 (en) |
| FR (1) | FR2274594A1 (en) |
| GB (1) | GB1452597A (en) |
| IL (1) | IL47442A (en) |
| IT (1) | IT1038852B (en) |
| NL (1) | NL7506751A (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3549769A (en) * | 1969-05-16 | 1970-12-22 | Ppg Industries Inc | Halogenated bicycloheptenones |
-
1974
- 1974-06-12 DE DE2428410A patent/DE2428410C2/en not_active Expired
-
1975
- 1975-06-06 NL NL7506751A patent/NL7506751A/en not_active Application Discontinuation
- 1975-06-09 CH CH741575A patent/CH613179A5/en not_active IP Right Cessation
- 1975-06-09 IL IL47442A patent/IL47442A/en unknown
- 1975-06-10 IT IT24217/75A patent/IT1038852B/en active
- 1975-06-10 GB GB2484775A patent/GB1452597A/en not_active Expired
- 1975-06-10 AT AT439475A patent/AT337665B/en not_active IP Right Cessation
- 1975-06-10 JP JP50069245A patent/JPS518253A/en active Pending
- 1975-06-11 CA CA75229121A patent/CA1049040A/en not_active Expired
- 1975-06-11 FR FR7518222A patent/FR2274594A1/en active Granted
- 1975-06-12 BE BE157291A patent/BE830184A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| GB1452597A (en) | 1976-10-13 |
| DE2428410A1 (en) | 1976-01-02 |
| NL7506751A (en) | 1975-12-16 |
| DE2428410C2 (en) | 1982-08-19 |
| IL47442A0 (en) | 1975-08-31 |
| ATA439475A (en) | 1976-11-15 |
| FR2274594B1 (en) | 1979-03-09 |
| BE830184A (en) | 1975-12-12 |
| FR2274594A1 (en) | 1976-01-09 |
| IL47442A (en) | 1978-01-31 |
| AT337665B (en) | 1977-07-11 |
| JPS518253A (en) | 1976-01-23 |
| IT1038852B (en) | 1979-11-30 |
| CH613179A5 (en) | 1979-09-14 |
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