Process for the Manufacture of Alkyl Ketene Dimers by Dimerization With

Office europeen des brevets (fi) Publication number: 0 619 289 A1

@ EUROPEAN PATENT APPLICATION

@ Application number : 94302165.9 @ Int. CI.5 : C07C 45/89, C07C 49/88

(22) Date of filing : 25.03.94

(30) Priority : 26.03.93 US 37203 @ Inventor : Zhang, Jian Jian (NMN) 10.05.93 GB 9309603 508 Waterford Drive, Gateway Farms Hockessin, Delaware 19707 (US) @ Date of publication of application : 12.10.94 Bulletin 94/41 (74) Representative : De Minvielle-Devaux, Ian Benedict Peter et al @ Designated Contracting States : CARPMAELS & RANSFORD AT BE DE ES FR GB IT NL PT SE 43, Bloomsbury Square London WC1A 2RA (GB)

@ Applicant : HERCULES INCORPORATED 1313 N. Market Street, Hercules Plaza Wilmington, Delaware 19894-0001 (US)

(54) Process for the manufacture of alky I ketene dimers by dimerization with tertiary amines.

(57) A process is disclosed for the synthesis of alkyl ketene dimers by the dehydrohalogenation of a Cg - C22 saturated or unsaturated linear fatty acid halide, comprising reacting the fatty acid chloride with a cyclic tertiary amine in an inert solvent at a temperature of up to 75°, separating tertiary amine hydrochloride salts from alkyl ketene dimer dissolved in the solvent, and recovering the alkyl ketene dimer from the solvent.

00 CM o> S o Q_ LU Jouve, 18, rue Saint-Denis, 75001 PARIS 1 EP 0 619 289 A1 2

This invention relates to a process for the synthe- German OLS 29 27 118 discloses a process to sis of alkyl ketene dimers by thedehydrohalogenation make diketenes using of a mixture of amines, which of Cs - C22 saturated or unsaturated linear fatty acid includes trimethylamine and at least one other terti- chlorides with tertiary amines in an inert solvent. ary amine. The trimethylamine is said to avoid the 5 high viscosity in the reaction mixtures with fatty acid BACKGROUND OF THE INVENTION halides that higher-substituted trialkylamines were found to cause. The other amine or amines may in- It is well known to react reaction of saturated lin- clude 1-methylpiperidine or 1-methylpyrrolidene. The ear fatty acid chlorides with linear tertiary amines in solvents used include alkanes and cyclo alkanes, as a variety of inert solvents to make disubstituted etha- 10 well as aromatic hydrocarbons, the reaction temper- nones, such as alkyl ketene dimers, which are useful ature is between 60 and 90°C, and the post-reaction as constituents of paper sizes as well as for other ap- heating is at 80°. Separation of LTEA-HCI precipitate plications in industry. For instance, U.S. Patents from the dimerization slurry involves liquid/liquid wa- 2,238,826 and 2,369,919, and an article by J. C. Sa- ter extraction of the LTEA-HCI salt, which introduces uer, Ketene Dimers from Acid Hal ides, in the Journal 15 moisture that is likely to cause hydrolysis of the alkyl of the American Chemical Society, 69 2444-8 (1947) ketene dimer and lessening of product yield. Yields of describe such reactions. Among the known useful 87 to 92% are obtained and presumably cannot be im- solvents are benzene, toluene, xylene, ligroin, chlor- proved further because of the inherent nature of the obenzene, dichlorobenzene, diethyl ether, dibutyl reaction. ether, chloroform, carbon tetrachloride, and trichloro- 20 There is a need for an alkyl ketene dimerization ethylene. The known families of solvents can be clas- process that avoids excessive viscosity and small sified as: amine-hydrochloride crystals in the dimerization slur- 1. alkanes and alkane petroleum fractions; ry, to facilitate the separation of amine-hydrochloride 2. cycloalkanes such as cyclohexane and methyl- precipitates in consistently high yields by such mech- cyclohexane; 25 anical separation methods as filtration, sedimenta- 3. aromatic hydrocarbons such as benzene, tol- tion and decantation, and without using uneconomic uene, and xylene; volumes of solvent, as disclosed in U.S Patent 4. chlorinated solvents such as chlorobenzene, 2,369,919. dichlorobenzene, chloroform, carbon tetrachlor- Also, because the conventional dimerization sol- ide, and trichloroethylene; and 30 vents used in present industrial applications are eith- 5. ethers such as diethyl ether. er unacceptably toxic, particularly benzene, diethyl The reaction in the said solvents to produce alkyl ether and toluene, used in the said U.S Patent ketene dimer (AKD) in solution also produces linear 2,369,91 9), or are known to be environmentally objec- tertiary amine hydrochloride (LTEA-HCI) as a finely tionable, including the whole class of the chlorinated divided precipitate. For some of the known solvent 35 solvents. There is therefore a need for a alkyl ketene families, problems encountered in the alkyl ketene di- dimerization process that uses a solvent with less merization reaction are low AKD selectivity (<80%), health and environmental problems than aromatic hy- an excessively viscous dimerization mixture, or very drocarbons, such as benzene and toluene or halogen- small amine-hydrochloride crystals in the dimeriza- ated solvents as used in the German OLS. tion slurry that are hard to separate by mechanical 40 procedures such as filtration and/or centrifugation Summary of the Invention and decantation. U.S. Patents 2,238,826 and 2,369,919 indicate According to the invention, a process for the syn- that saturated acyclic amines free of active hydrogen thesis of alkyl ketene dimers by reacting a C8 - C22 are preferred for the said reaction, although they in- 45 saturated or unsaturated linear fatty acid chloride dicate that suitable amines include 1-methylpiperi- with a cyclic tertiary amine in an inert solvent at a tem- dine, 1-isopropylpiperidine, and 1-methylpyrrolidene. perature of up to 75°C, mechanically separating ter- From the disclosure, of the '919 Patent it is apparent tiary amine hydrochloride salts from the alkyl ketene that the use of the preferred linear amines requires a dimer in the solvent, and recovering the alkyl ketene very dilute reaction mixture (100-200 parts solvent 50 dimer by evaporation of the solvent, characterized in per tenth mol of each reactant to obtain a yield of 60 that the tertiary amine has the structure: to 97%. That degree of dilution appears to be necessary to prevent the dimerization reaction slurry from becoming highly viscous, which would make separa- f tion of a linear tertiary amine hydrochloride (LTEA- HCI) precipitate from the reaction mixture extremely difficult and filtration disclosed in impossible by as (CH2)n the patent. 2 3 EP 0 619 289 A1 4 in which R represents a CrC7 substituted or unsub- It is possible to add the fatty acid chloride to the stituted alkyl group and n is an integer from 2 to 10. tertiary amine solution in the aliphatic hydrocarbon Preferably the alkyl group R contains one to three solvent, or to add the tertiary amine to the fatty acid carbon atoms and n is four or five, and more prefer- chloride solution in aliphatic hydrocarbon, orsimulta- ably the tertiary amines for use in the invention are N- 5 neously to add both fatty acid chloride and tertiary methylpyrrolidine, N-methylpiperidine, or N-ethylpi- amine to the solvent. However, the preferred method peridine. The most preferred cyclic tertiary amine is is dropwise addition of the fatty acid chloride, either N-methylpyrrolidine. as is or dissolved in aliphatic hydrocarbon solvent, to The preferred solvents are cycloalkanes or al- a tertiary amine solution, also in aliphatic hydrocar- kanes, preferably containing from 5 to 10 carbon 10 bon solvent. atoms. The cycloalkanes may be either unsubstituted The reaction of the dehydrochlorination of fatty or substituted by an alkyl group having one to four car- acid chloride by tertiary amine is exothermic. The ad- bon atoms, and the alkanes may be either linear or dition of fatty acid chloride to the tertiary amine sol- branched. The more preferred solvents are cycloalk- ution in aliphatic hydrocarbon solvent is preferably anes. 15 carried out at a temperature ranging from room tem- The amount of solvent used for the reaction is perature to 70°C, if necessary accompanied by cool- preferably between about 30% and 100% by mass of ing to prevent the temperature from exceeding 70°C. the solvent, based upon the mass of the fatty acid In order to complete the dehydrochlorination re- chloride or mixture of fatty acid chlorides. More pre- action of the fatty acid chloride and the dimerization ferably, the amount of solvent is just above the 20 reaction of ketene monomer, the complete reaction amount needed to avoid the saturation concentration mixture is preferably maintained at an elevated tem- of alkyl ketene dimer in the solvent at the reaction cy- perature of up to 70°C for at least 30 minutes and up cle temperatures, namely, to provide an alkyl ketene to 5 hours, preferably at a temperature of at least dimer concentration in the reaction slurry in the range 50°C and more preferably between 55 and 65°C for of 1 .0 molar to 3.65 molar. 25 between 2 and 3 hours. This post-reaction heat treat- ment generally lowers the viscosity of the reaction DETAILED DESCRIPTION OF THE INVENTION slurry and improves the alkyl ketene dimer quality. As indicated above, the amount of solvent used Among the cycloalkanes, the best results are se- for the reaction is preferably at least sufficient and cured by use of cyclohexane or methylcyclohexane, 30 preferably in excess of the amount necessary to in particular methylcyclohexane. The preferred al- maintain the alkyl ketene dimer in solution at the re- kane is heptane. The most preferred combination of action mixture. In some circumstances it may be de- cyclic tertiary amine and solvent is methylpyrrolidine sired to add additional solvent during the course of the and methylcyclohexane reaction to avoid the precipitation of the alkyl ketene In the process according to the invention, long- 35 dimer along with the tertiary amine hydrochloride chain carboxylic acid halides with 12 to 22 carbon salt. atoms, or their mixtures, are preferred. Among the ha- For the physical separation of the tertiary amine lides, the chlorides are the most suitable. Suitable hydrochloride crystals from the alkyl ketene dimer chlorides are conventionally derived from their corre- solution in the reaction solvent, vacuum filtration, or sponding carboxylic acids by chlorination with chlor- 40 filtration hastened by the use of centrifugal force may inating reagents such as, phosphorus trichloride, be satisfactory, preferably the latter. In general, the phosphorus pentachloride, thionyl chloride, and amine-hydrohalide precipitates must have all linear phosgene. Furthermore, mixtures of carboxylic acid dimensions greater than 2 microns to use mechani- chlorides of naturally occurring fatty acids are suit- cally assisted separation. Best results are secured by able for this process, e.g., fatty acids from tallow oil 45 use of the filtration hastened by centrifugal force at and palm oil. Particular preferred is a mixture of pal- a temperature from 65°C to 75°C to avoid the precip- mitoyl chloride and stearyl chloride as the starting itation of alkyl ketene dimer. material. After the physical separation of the precipitated According to the invention, the quantity of tertiary tertiary amine hydrochloride salts, the final stage of amines used is preferably a 1.00-1.15 molar ratio rel- so the process is the recovery of alkyl ketene dimer by ative to the fatty acid chloride, more preferably a 1.10 the removal of the solvent and the remaining tertiary molar ratio. A quantity of amine less than 1.00 molar amine. Conventional techniques for removing volatile relative to the fatty acid chloride can result in an in- substances from relatively non-volatile substances complete reaction and poorer alkyl ketene dimer qual- are appropriate, including distillation or vacuum dis- ity. On the other hand, an amine level exceeding a ss ti Nation. Preferably the distillation process is per- 1.15 molar ratio is not economically justified and may formed under an inert atmosphere, and the solvent is also adversely affect the quality of the alkyl ketene di- recovered for re-use. mer. This invention is further disclosed by the follow- 3 5 EP 0 619 289 A1 6 ing examples. EXAMPLE 4

EXAMPLE 1 This Example shows the production of an alkyl ketene dimer using N-methylpyrrolidine in heptane as This Example shows the production of an alkyl 5 the dimerization solvent. ketene dimer using N-methylpyrrolidine in methylcy- Alkyl ketene dimerwas prepared using N-methyl- clohexane. pyrrolidine in heptane under the same reaction con- N-methylpyrrolidine, 140.25 g (1.65 molar), in dition as Example 1. Analysis of the product showed 600 ml of methylcyclohexane was placed in an oven that it contained an alkyl ketene dimer assay of 87.3% dried 1 L 5-necked flask equipped with nitrogen in- 10 and a non-volatile content of 99.8%. let/outlet. PTFE paddle stirrer, condenser, and dropping funnel. Palmitoyl chloride, 411 g (1.5 mol), was EXAMPLE 5 then added dropwise over a period of 50 minutes with stirring, during which the temperature rises to This Example shows the production of an alkyl 35~45°Cfrom room temperature. (The N-methylpyr- 15 ketene dimer using N-methylpyrrolidine in methylcy- rolidine molar amount was 1.1 times molar amount of clohexane. the palmitoyl chloride). 140 parts (by weight) of N-methylpyrrolidine in After the addition was completed, the fluid reac- 460 parts of methylcyclohexane was placed in an tion mixture was heated and maintained at 60°C for oven dried 1 L 5-necked flask equipped with nitrogen 90 minutes. The tertiary amine hydrochloride precip- 20 inlet/outlet, PTFE paddle stirrer, condenser, and itate was separated from the alkyl ketene dimer sol- dropping funnel. 410 parts of palmitoyl chloride was ution in methylcyclohexane by suction filtration fol- then added dropwise over a period of 50 minutes with lowed by washing the tertiary amine hydrochloride stirring, during which the temperature rose to 35 ~ salt cake with a small amount of hot (~70°C) methyl- 45°C from room temperature. cyclohexane. The filtrate containing the alkyl ketene 25 After the addition was completed, the fluid reac- dimer was then stripped off the solvent and the ex- tion mixture was heated and maintained at 60°C for cess N-methylpyrrolidine under reduced pressure us- 90 minutes. The tertiary amine hydrochloride precip- ing a rotary evaporator at 55°C to obtain the alkyl ke- itate was separated from the alkyl ketene dimer sol- tene dimer. Analysis of the product showed that it con- ution in methylcyclohexane by suction filtration follow tains an alkyl ketene dimer assay of 91 .3% and a non- 30 by wash the tertiary amine hydrochloride salt cake volatile content of 99.8%. with 100 parts of hot (~70°C) methylcyclohexane. The filtrate containing the alkyl ketene dimer was EXAMPLE 2 then stripped off the solvent and the excess N-methylpyrrolidine under reduced pressure using a rotary The Example shows the production of an alkyl ke- 35 evaporator at 55°C to obtain the alkyl ketene dimer. tene dimer using N-methylpyrrolidine in cyclohexane. Analysis of the product showed that it contains an al- Alkyl ketene dimer was prepared, using N-me- kyl ketene dimer assay of 91.3% and a non-volatile thylpyrrolidine in the cyclohexane dimerization sol- content of 99.8%. vent and using the same conditions in Example 1 , except the reaction temperature was 40°C. Analysis of 40 EXAMPLE 6 the product showed that it contained an alkyl ketene dimer assay of 93.0% and a non-volative content of This Example shows the preparation of an alkyl 99.8%. ketene dimer using N-methylpyrrolidine in cyclohexane. EXAMPLE 3 45 Alkyl ketene dimerwas prepared using N-methylpyrrolidine in the cyclohexane dimerization solvent This Example shows the production of an alkyl and following the same procedure as in Example 5, ketene dimer using N-methylpiperidine in methylcy- except the reaction temperature was 40°C. Analysis clohexane. of the product showed that it contained an alkyl ke- Alkyl ketene dimerwas prepared using N-methyl- 50 tene dimer assay of 93.0% and a non-volatile content piperidine as a base in the methylcyclohexane dimer- of 99.8%. ization solvent, underthe same reaction conditions as Example 1 . Analysis of the product showed that it con- EXAMPLE 7 tains an alkyl ketene dimer assay of 91 .8% and a non- volatile content of 99.7%. 55 This Example shows the preparation of an alkyl ketene dimer using N-methylpiperidine in methylcyclohexane An alkyl ketene dimerwas prepared using N-me- 4 7 EP 0 619 289 A1 8 thylpiperidine as a base in methylcyclohexane as the cloalkanes substituted by an alkyl group having dimerization solvent, and following the same reaction one to four carbon atoms. procedure as the Example 5. Analysis of the product showed that it contained an alkyl ketene dimer assay 5. A process forthe synthesis of alkyl ketene dimers of 91 .8% and a non-volatile content of 99.7%. 5 as claimed in claim 3 or 4, further characterized in that the solvent is selected from the group con- EXAMPLE 8 sisting of heptane, cyclohexane, and methylcy- clo-hexane. This Example shows the preparation of an alkyl ketene dimer using N-methylpyrrolidine in heptane. 10 6. A process forthe synthesis of alkyl ketene dimers Alkyl ketene dimerwas prepared using N-methyl- as claimed in any of the preceding claims, further pyrrolidine in heptane as the dimerization solvent and characterized in that the amount of solvent is just following the same reaction proceduue as in Example above the amount needed to provide an alkyl ke- 5. Analysis of the product showed that it contained an tene dimer concentration in the reaction slurry in alkyl ketene dimer assay of 87.3% and a non-volatile 15 the range of 1 .0 molar to 3.65 molar. content of 99.8%. 7. A process forthe synthesis of alkyl ketene dimers as claimed in as claimed in any of the preceding Claims claims, in which the fatty acid halide or mixture 20 is a linearfatty acid chloride or a mixture compris- 1 . A process for the synthesis of alkyl ketene dimers ing a linearfatty acid chloride. by the dehydrohalogenation of a C8 - C22 saturated or unsaturated linear fatty acid halide, or a 8. A process forthe synthesis of alkyl ketene dimers mixture of C8 - C22 linear fatty acid halides, com- as claimed in any of the preceding claimsjn prising reacting the fatty acid halide with a cyclic 25 which the fatty acid chloride or mixture comprises tertiary amine in an inert solvent at a temperature a linearfatty acid chloride having 12 to 22 carbon of up to 75°, mechanically separating tertiary atoms. amine hydrochloride salts from alkyl ketene dimer dissolved in the solvent, and recovering the 9. A process forthe synthesis of alkyl ketene dimers alkyl ketene dimer from the solvent, character- 30 as claimed in any of the preceding claims, in ized in that the tertiary amine has the structure: which the alkyl group R contains one to three carbon atoms and n is four or five.

f 10. A process forthe synthesis of alkyl ketenedimers 35 as claimed in claim 9, in which the tertiary amine N ( ) is selected from the group consisting of N-methylpyrrolidine, N-methylpiperidine, and N-ethyl- (CH2)n piperidine.

in which R represents a CrC7 substituted or un- 40 11. A process forthe synthesis of alkyl ketene dimers substituted alkyl group and n is an integer from 2 as claimed in claim 9, in which the tertiary amine to 10. is N-methylpyrrolidine.

2. A process for the synthesis of alkyl ketene dimers 12. A process forthe synthesis of alkyl ketene dimers as claimed in claim 1 or 2, further characterized 45 as claimed in claim 9, in which the solvent is me- in that the solvent is selected from the group con- thylcyclohexane. sisting of cycloalkanes and alkanes. 13. A process forthe synthesis of alkyl ketene dimers 3. A process for the synthesis of alkyl ketene dimers as claimed in any of the preceding claims in which as claimed in claim 1 or 2, further characterized so the quantity of tertiary amine used is 1.00-1.15 in that the solvent is selected from the group con- molar relative to the fatty acid chloride. sisting of cycloalkanes and alkanes containing 5 to 1 0 carbon atoms. 14. A process forthe synthesis of alkyl ketene dimers as claimed in claim 12 in which the quantity of ter- 4. A process for the synthesis of alkyl ketene dimers 55 tiary amines used is 1 .1 molar relative to the fatty as claimed in claim 3, further characterized in acid chloride. that the cycloalkanes are selected from the group consisting of unsubstituted cycloalkanes and cy- 15. A process forthe synthesis of alkyl ketenedimers 5 9 EP 0 619 289 A1 10

as claimed in any of the preceding claims, in which the fatty acid chloride is added dropwise to the tertiary amine dissolved in the solvent.

1 6. A process for the synthesis of alkyl ketene dimers 5 as claimed in in any of the preceding claims, in which the fatty acid chloride is added to the tertiary amine at a temperature in the range of room temperature to 70°C. 10 1 7. A process for the synthesis of alkyl ketene dimers as claimed in any of the preceding claims, in which the reaction includes the step of maintained the reaction mixture at a temperature in the range of room temperature to 70°Cforat least 15 30 minutes and up to 5 hours before the tertiary amine hydrochloride salts are separated.

1 8. A process for the synthesis of alkyl ketene dimers as claimed in claim 16, in which the reaction mix- 20 ture is maintained at a temperature between 55 and 65°C for between 2 and 3 hours.

19. A process for the synthesis of alkyl ketenedimers as claimed in any of the preceding claims, in 25 which the separation of the tertiary amine hydrochloride salts includes the step of filtration.

20. A process for the synthesis of alkyl ketene dimers as claimed in any of the preceding claims, in 30 which the separation of the tertiary amine hydrochloride salts includes the step of decantation after centrifugation.

21. An alkyl ketene dimer prepared by the process 35 claimed in any of the preceding claims, containing residual solvent.

22. An aqueous dispersion of an alkyl ketene dimer prepared by the process claimed in any of the 40 preceding claims.

6 EP 0 619 289 A1

UUI UpCBll @ lUCIlt Application Number Office UUKUFUAIN SEARCH REPORT EP 94 30 2165

uulumi!,i> la UUNS1JJEKKU TO BE RELEVANT x.HHuvu vi hhuwkh "nil mmi-ituon, wnerc appropriate, Keievant CLASSIFICATION OF THE of relevant passages to claim APPLICATION (IntCLS) Jt-A-/^B shu -.HUblhK, R.) Z7 April 1944 C07C45/89 * i,z,7-iq the whole document * C07C49/88 JS-A-2 369 919 (SAUER, J.S.) U2,7-iq PAGE 3, L.H.COL., LINES 8-14 PAGE 3, R.H.COL., LINES 22-24

PATENT ABSTRACTS OF JAPAN 21,22 *ol. 13, no. 72 (C-570)17 February 1989 5, JP-A-63 264 545 (NIPPON OIL & FATS CO -TD) 1 November 1988 * abstract *

TECHNICAL FIELDS SEARCHED (IntCLS) :o7C

me iirooii xorvn repgrt nas Been arawn up tor HI claims waj OTa^wuHal m |bjb igara 1UNICH 4 August 1994 ioetz, G : ueory or principle underlying the invention : : earlier patent document, but published on, or after the filing date : particularly relevant if combined with another 1 : document cited in the application document of the same category : document cited for other i : technological background @ reasons : non-written disclosure I member of the : intermediate document : same patent family, corresponding i document