CA2023057A1 - Process for reducing the content of primary and secondary amine in a tertiary amine - Google Patents
Process for reducing the content of primary and secondary amine in a tertiary amineInfo
- Publication number
- CA2023057A1 CA2023057A1 CA 2023057 CA2023057A CA2023057A1 CA 2023057 A1 CA2023057 A1 CA 2023057A1 CA 2023057 CA2023057 CA 2023057 CA 2023057 A CA2023057 A CA 2023057A CA 2023057 A1 CA2023057 A1 CA 2023057A1
- Authority
- CA
- Canada
- Prior art keywords
- amine
- primary
- anhydride
- tertiary amine
- secondary 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.)
- Abandoned
Links
- 150000003512 tertiary amines Chemical class 0.000 title claims abstract description 34
- 150000003141 primary amines Chemical class 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 22
- 150000003335 secondary amines Chemical class 0.000 title abstract description 32
- 150000008064 anhydrides Chemical class 0.000 claims abstract description 22
- 230000009467 reduction Effects 0.000 claims abstract description 5
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 23
- 125000004432 carbon atom Chemical group C* 0.000 claims description 14
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 claims description 6
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 claims description 6
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- 125000000467 secondary amino group Chemical class [H]N([*:1])[*:2] 0.000 claims 3
- 239000002253 acid Substances 0.000 abstract description 10
- 150000001408 amides Chemical class 0.000 abstract description 7
- 150000001875 compounds Chemical class 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 17
- 150000001412 amines Chemical class 0.000 description 11
- 150000008065 acid anhydrides Chemical class 0.000 description 9
- 239000000047 product Substances 0.000 description 9
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 7
- -1 alkyl radical Chemical class 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 description 4
- WQDUMFSSJAZKTM-UHFFFAOYSA-N Sodium methoxide Chemical compound [Na+].[O-]C WQDUMFSSJAZKTM-UHFFFAOYSA-N 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 150000003254 radicals Chemical class 0.000 description 4
- 239000011541 reaction mixture Substances 0.000 description 4
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- LQZZUXJYWNFBMV-UHFFFAOYSA-N dodecan-1-ol Chemical compound CCCCCCCCCCCCO LQZZUXJYWNFBMV-UHFFFAOYSA-N 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- FALRKNHUBBKYCC-UHFFFAOYSA-N 2-(chloromethyl)pyridine-3-carbonitrile Chemical compound ClCC1=NC=CC=C1C#N FALRKNHUBBKYCC-UHFFFAOYSA-N 0.000 description 2
- DLFVBJFMPXGRIB-UHFFFAOYSA-N Acetamide Chemical compound CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 description 2
- 229910014033 C-OH Inorganic materials 0.000 description 2
- 229910014570 C—OH Inorganic materials 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 2
- 238000007098 aminolysis reaction Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- OMEMQVZNTDHENJ-UHFFFAOYSA-N n-methyldodecan-1-amine Chemical compound CCCCCCCCCCCCNC OMEMQVZNTDHENJ-UHFFFAOYSA-N 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 229940014800 succinic anhydride Drugs 0.000 description 2
- JPSKCQCQZUGWNM-UHFFFAOYSA-N 2,7-Oxepanedione Chemical compound O=C1CCCCC(=O)O1 JPSKCQCQZUGWNM-UHFFFAOYSA-N 0.000 description 1
- 235000013162 Cocos nucifera Nutrition 0.000 description 1
- 244000060011 Cocos nucifera Species 0.000 description 1
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 1
- DFPAKSUCGFBDDF-UHFFFAOYSA-N Nicotinamide Chemical compound NC(=O)C1=CC=CN=C1 DFPAKSUCGFBDDF-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 239000002168 alkylating agent Substances 0.000 description 1
- 229940100198 alkylating agent Drugs 0.000 description 1
- 125000002947 alkylene group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 1
- YHASWHZGWUONAO-UHFFFAOYSA-N butanoyl butanoate Chemical compound CCCC(=O)OC(=O)CCC YHASWHZGWUONAO-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000012084 conversion product Substances 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 125000003438 dodecyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- JRBPAEWTRLWTQC-UHFFFAOYSA-N dodecylamine Chemical compound CCCCCCCCCCCCN JRBPAEWTRLWTQC-UHFFFAOYSA-N 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- KKHUSADXXDNRPW-UHFFFAOYSA-N malonic anhydride Chemical compound O=C1CC(=O)O1 KKHUSADXXDNRPW-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- WCYWZMWISLQXQU-UHFFFAOYSA-N methyl Chemical compound [CH3] WCYWZMWISLQXQU-UHFFFAOYSA-N 0.000 description 1
- 125000001421 myristyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 150000004005 nitrosamines Chemical class 0.000 description 1
- 125000002347 octyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000001117 oleyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])/C([H])=C([H])\C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- WYVAMUWZEOHJOQ-UHFFFAOYSA-N propionic anhydride Chemical compound CCC(=O)OC(=O)CC WYVAMUWZEOHJOQ-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 125000004079 stearyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000003760 tallow Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000005292 vacuum distillation Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/84—Purification
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Abstract of the disclosure:
Process for reducing the content of primary and secondary amine in a tertiary amine A process is described for reducing the content of primary and secondary amine in a tertiary amine in which the tertiary amine to be treated is brought into contact with an organic anhydride until the reduction sought in the content of primary and secondary amine is achieved.
Bringing the compounds into contact as mentioned, which as a rule is carried out at a temperature of 20 to 200°C, results in the formation, from the primary amine and the secondary amine, which is particularly undesirable, of the compounds acid and/or acid amide. After removal of these compounds, which are comparatively harmless, a completely pure tertiary amine is present.
Process for reducing the content of primary and secondary amine in a tertiary amine A process is described for reducing the content of primary and secondary amine in a tertiary amine in which the tertiary amine to be treated is brought into contact with an organic anhydride until the reduction sought in the content of primary and secondary amine is achieved.
Bringing the compounds into contact as mentioned, which as a rule is carried out at a temperature of 20 to 200°C, results in the formation, from the primary amine and the secondary amine, which is particularly undesirable, of the compounds acid and/or acid amide. After removal of these compounds, which are comparatively harmless, a completely pure tertiary amine is present.
Description
'7 .~
HOECHST AXTIENGESELLSCHAFT HOE 89/F 912 Dr.GL-nu Werk Gendorf Process for reducing the content of primary and secondary amine in a tertiary amine Description The inven~ion relates to a process for reduaing the content of primary and ~econdary amine in a tertiary amine.
As is known, tertiary amines in general contain a larger 1~ or smaller amount of primary and secondary amine bscause of their method of preparation. ~his particularly applies to those tertiary amine products which have been prepared by the very frequently used aminolysis process, tha~ is to say by reaction of secondary amines with alcohols as alkylating agents in the presence of dehydroge-nation/hydrogenation catalysts, compare U.S. Patent 4,I38,437, in particular Example l, lines 46 to 48, and British Patent 1,585,480, in particular column 1, lines :~ :
54 to 59. ~he tertiary amine obtained by this process, which is advantageous per se, as a rule has a content of primary and/or secondary amine of up to about 2 parts by weight in total per 100 parts ~y weight of tertiary ~` amine, the secondary amine representing the main pro-portion in comparison with the primary amine (there are usually mere}y traces of the primary amine). However, precisely the secondary amines are a particularly unde-sirable impurity, because nitrosamines are known to be able to form from these amines. The~primary and secondary amines, in particular in the form of the so-called methylalkylæmines, often cannot be separated by distil-lation because of the }ow difference in boiling point.
This particularly applies if the products are so-called chain blends ~which is as a rule the case) in which the boiling points of the mono- and dimethylalkylamines even overlap.
HOECHST AXTIENGESELLSCHAFT HOE 89/F 912 Dr.GL-nu Werk Gendorf Process for reducing the content of primary and secondary amine in a tertiary amine Description The inven~ion relates to a process for reduaing the content of primary and ~econdary amine in a tertiary amine.
As is known, tertiary amines in general contain a larger 1~ or smaller amount of primary and secondary amine bscause of their method of preparation. ~his particularly applies to those tertiary amine products which have been prepared by the very frequently used aminolysis process, tha~ is to say by reaction of secondary amines with alcohols as alkylating agents in the presence of dehydroge-nation/hydrogenation catalysts, compare U.S. Patent 4,I38,437, in particular Example l, lines 46 to 48, and British Patent 1,585,480, in particular column 1, lines :~ :
54 to 59. ~he tertiary amine obtained by this process, which is advantageous per se, as a rule has a content of primary and/or secondary amine of up to about 2 parts by weight in total per 100 parts ~y weight of tertiary ~` amine, the secondary amine representing the main pro-portion in comparison with the primary amine (there are usually mere}y traces of the primary amine). However, precisely the secondary amines are a particularly unde-sirable impurity, because nitrosamines are known to be able to form from these amines. The~primary and secondary amines, in particular in the form of the so-called methylalkylæmines, often cannot be separated by distil-lation because of the }ow difference in boiling point.
This particularly applies if the products are so-called chain blends ~which is as a rule the case) in which the boiling points of the mono- and dimethylalkylamines even overlap.
- 2 -The object of the invention accordingly is to provide a process with which a substantial to complete reduction in the amount of impurities in question is possible, ~o that a tertiary smine which is practically free from prLmary and secondary amines can be achieved. It should further-more be possible to carry out the novel proces~ easily and with li~tle expenditure.
The process according to the in~ention for reducing the content of primary and secondlary amine in a tertiary amine comprises the tertiary amine to be treated bringing into contact with an organic anhydride until the reduc-tion sought in the content of primary and secondary amine is achieved.
The chemical reaction on which the purification process -according to the invention is based probably proceeds in accordance with the equations below. The equations contain acetic anhydride, succinic anhydride and phthalic ~; anhydride as the organic anhydride and dodecylamine and methyldodecylamine as the primary and secondary amine (that is to say the amines to be reacted):
,'.
~` CH3-CO O O
;~ ~ o + H2NC12H25 > CH3-C + CH3-C
CH3-CO OH NHC12H25 ~ `
.
O ~ HN , j -~ CH3-C ~ CH3-C~
cl2H25 .
O
O + H2Ncl2H25 >
CH2 -c-NHcl2H2 5 CH2-CO \\
// ' CH2-C ~CH3 1 2-C-OH
O + HN > O
2_~_/ C12H2S ~ :H,2-C-N-CH3 C12~I25 ::
+ NzNC12N25 ~ I~C-NHC12H25 ~ O
~CO ~N3 C-OH
co C12H2 5 ~C-N-CH3 12H25 .
As the equations show, acid and acid amide or amide acid (likewise called acid-amide below) are formed from the undesirable primary and secondary amine and the anhydride -~
employed. The components now present in the tertiary ~ 5 amine, that is to say acid and~or acid amide, either can -~ be removed, for example in the context of a distillation, , or can remain in the tertiary amine since they result in -~
no noticeable disadvantages, which applies in particular `
to the acid amide.
Because of the high reactivity of the anhydrides, the reaction according to the invention often also already proceeds at low temperatures, so that merely brinqing the tertiary amine to be treated into contact with the anhydride alr~eady produces the conversion sought. On the other hand, higher temperatures can also be used. A ~
:`
:
higher temperature i8 appropriate if the tertiary amine product to be ~reated has a relatively high melting point and/or if a particularly short reaction time i~ desired.
The process according to the invention i6 accordingly as a rule carried out at a temperature of 20 to 200C, preferably at a temperature of 50 to 150~C. The reaction tLme, which is the time required fox reaction o~ the anhydride with the primary and/or secondary 2~mine, i8 as a rule 0.3 to 3 hours. It clearly depends in particular on the reaction temperature and on the degree of reaction sought.
As regards the amount of anhydride, it has proved advan-tageous to employ this in at least the equimolar ratio to the primary and/or secondary amine present. ~he amount of anhydride is thus preferably 1 to 2 mol, and in par-ticular 1.05 to 1.5 mol, per mol of amine to be reacted.
; The amount of primary and secondary amine in the tertiary amine to be treated can be determined, for example, from the known reaction of the tertiary 2~nine product with carbon disulfide and titration of the thioacids formed from the primary and secondary amine.
: . .
The nature of the organic anhydrides to be employed ; according to the invention is not in itself critical. It goes without saying that an anhydride which suits the tertiary amine to be treated will be employed. Possible anhydrides are thus aliphatic, cycloaliphatic or aromatic acid anhydrides. The preferred acid anhydrides are those of the following formula Rl-CO
\
O
in which Rl and R2 are an alkyl radical having 1 to 18 carbon atoms, preferably 2 to 4 carbon atoms, or an alkenyl radical having 2 to 18 carbon atoms, preferably 2 to 4 carbon atoms, or R1 and R2 together are an alkylene s~
~2~ 7 radical having 1 to 10 carbon atoms, preferably 2 to 4 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical. Preferred acid anhydrides are thus those of monocarboxylia acids, preferably saturated (that is to say R1 and R2 are identi-cal and are the alXyl radical mentioned), such as acetic anhydride, propionic anhydride, butyric anhydride and the like, and furthermore those of saturated or unsaturated dicarboxylic acids (that is to say R1 and R2 together are the divalent radical mentioned), such as malonic anhy-dride, succinic anhydride, adipic anhydride, maleic anhydride and the like, and phthalic anhydride. Par-ticularly preferred acid anhydrides are, especially for practica- reasons, acetic anhydride and phthalic anhy-dride.
According to a preferred embodiment, the process accor-ding to the invention is carried out by adding the acid anhydride in at least the stoichiometric (equimolar) amount, based on the primary and secondary amine present (compare above equations), preferably in an amount of 1 to 2 mol, in particular l.OS to 1.5 mol, per mol of primary and secondary amine, to the tertiary amine to be treated, heating the mixture to a temperature of 20 to 200C, preferably 50 to 150C, while stirring, and keeping the mixture at this temperature, likewise while stirring, until the primary and secondary amine pre~ent has reached the lower limit value sought or has been converted completely. The reaction can be carried out under normal pressure or under pressure. Removal of excess acid anhydride and the components formed, that is to say acid and acid amide, can be achieved, if desired, for example, by distillation. The acid and acid anhydride can also be separated off from the tertiary amine, for example, by treating the reaction mixture with alkali (solid or in the form of an aqueous solution) to convert the acid and acid anhydride into the corresponding alkali metal salts. The tertiary amine can now be obtained without problems as the distillate from the mixture now - 6 2~2~7 -present, whereas the metal salts mentioned remain in the bottom product. As already mentioned above, as a rule the acid amide present results in no particular disadvantages in the tertiary amine.
The tertiary amines in ~he context of the present inven-tion are prefexably those of the following formula in which R3 is an alkyl radical or an alkenyl radical having 6 to 24 carbon atoms, preferably 8 to 22 carbon atoms, and R4 and R5, which are preferably identical, are an alkyl~radical having 1 to 4 carbon atoms, preferably the methyl radical. Examples which may be mentioned for R3 are octyl, dodecyl, tetradecyl, stearyl, oleyl, tallow fat alkyl and coconut alkyl.
. :
The abovementioned aminolysis is also shown in the form of an e~uation below, dodecyl alcohol (lauryl alcohol) functioning as the alcohol and dimethylamine as the amine:
` :
Cl2H2s-oH + H-N > C12H25-N + H2O
In addition to thisl main reaction, as is ~known a dig-proportionation of the dimethylamine into, inter alia, monomethylamine, which forms the secondary amine methyl-dodecylamine with the alcohol present, takes place. The undesirable slecondary amines in question accordingly in general correspond to the formula R3-NH-R4, in which R3 and R4 have the meanings given.
The process according to the invention has a number of 2~3~
advantages. It is a simple method which requires little expenditure for partial to complete elimination of primary and secondary amine in a ter~iary amine, it being possible for a tertiary amine which is practically free from the impurities mentioned to be obtained without problems. The reagent used in the process according to the invention, tha~ i8 to ~ay the acid anhydride, is in general readily obtainable and highly reactive. A com-plete conversion can in this way already be achieved under relatively mild reaction conditions. The conversion products formed in the reaction, if they are troublesome at all, can as a rule be removed without problems, so that a tertiary amine which is not only free from primary and secondary amines but also free from other compounds and therefore completely pure can be achieved.
The invention will now be illustrated in more detail by examples.
Example 1 100 g of tertiary amine are to be treated, of the formula Cl214-N(CH3)2, which contained 1.8 g (0.008 mol) of secon-dary amine of the formula Cl2l4-NH-CH3, were introduced into a reaction vessel equipped with a stirrer, reflux condenser and thermometer, and 0.83 g (0.008 mol) of acetic anh~dride was added. The mixture was heated to 100C, while stirring, and kept at this temperature for 1 hour. After the reaction mixture has been cooled, the content of secondary amine was determined. It was only 0.3 parts by weight in 100 parts by weight of tertiary amine.
Examples 2 to 8 These examples were carried out analogously to Example 1.
The tertiary amines to be treated (these are dimethyl-alkylamines, as in Example 1) and their content of secondary amine, the aci~ anhydride employed, the molar J u~ ~ ~t3 ~
ratio of acid anhydride to secondary amine, the reaction temperature, the reaction time and the reduction achieved in the content of secondary amine are summarized in the following table, which also contains Example 1 for simplicity. The following is al~;o mentioned regarding the table, by way of explanation: the alkyl radical of the dimethylalkylamine is shown in column 2 and the values in respect of the content of secondary amine in the third and last column are percentages by weight, based on the tertiary amine to be treated (crude amine).
As regards the examples, it should also be stated that in those where phthalic anhydride is used as the reagent for the secondary amine, the excess phthalic anhydride and the phthalamido acid formed can be removed simply by distillation of the reaction mixture, the phthalic anhydride and the phthalamido acid remaining in the bottom product, because of the boiling point differences, whilst the top product is the pure tertiary amine sought.
In examples where acetic anhydride is used, the excess anhydride and the acetic acid formed are removed in the following manner: a 30~ strength by weight methanolic sodium methylate solution was added to the reaction mixture so that an amount of sodium methylate which corresponds to the molar amount of acetic acid and acetic anhydride present was introduced, after which the mixture was stirred at 70C for 0.25 hours for complete conver-sion of the acetic acid and acetic anhydride into the corresponding sodium salts. Vacuum distillation gave the (acetamide-containing) tertiary amine as the top product, whilst the sodium salts mentioned remained in the bottom product.
2~2~7 . _.
~ ,o,o,,,~
~'o-~O=
..._ '~U 0r~o . . _ ~ ,o ~ ~
~rl ~ ~ 11~ N _I ~ In U~ O ~:
~ W O ~
'1:) 'C1 ~ 'Cl h h h h a ~:~ CO~ ~ ooo ._ . ~ .. . . ..
.~ ~ u u u u 5 u u _ _ ._ E~ ~ ~ ~:
: . .
The process according to the in~ention for reducing the content of primary and secondlary amine in a tertiary amine comprises the tertiary amine to be treated bringing into contact with an organic anhydride until the reduc-tion sought in the content of primary and secondary amine is achieved.
The chemical reaction on which the purification process -according to the invention is based probably proceeds in accordance with the equations below. The equations contain acetic anhydride, succinic anhydride and phthalic ~; anhydride as the organic anhydride and dodecylamine and methyldodecylamine as the primary and secondary amine (that is to say the amines to be reacted):
,'.
~` CH3-CO O O
;~ ~ o + H2NC12H25 > CH3-C + CH3-C
CH3-CO OH NHC12H25 ~ `
.
O ~ HN , j -~ CH3-C ~ CH3-C~
cl2H25 .
O
O + H2Ncl2H25 >
CH2 -c-NHcl2H2 5 CH2-CO \\
// ' CH2-C ~CH3 1 2-C-OH
O + HN > O
2_~_/ C12H2S ~ :H,2-C-N-CH3 C12~I25 ::
+ NzNC12N25 ~ I~C-NHC12H25 ~ O
~CO ~N3 C-OH
co C12H2 5 ~C-N-CH3 12H25 .
As the equations show, acid and acid amide or amide acid (likewise called acid-amide below) are formed from the undesirable primary and secondary amine and the anhydride -~
employed. The components now present in the tertiary ~ 5 amine, that is to say acid and~or acid amide, either can -~ be removed, for example in the context of a distillation, , or can remain in the tertiary amine since they result in -~
no noticeable disadvantages, which applies in particular `
to the acid amide.
Because of the high reactivity of the anhydrides, the reaction according to the invention often also already proceeds at low temperatures, so that merely brinqing the tertiary amine to be treated into contact with the anhydride alr~eady produces the conversion sought. On the other hand, higher temperatures can also be used. A ~
:`
:
higher temperature i8 appropriate if the tertiary amine product to be ~reated has a relatively high melting point and/or if a particularly short reaction time i~ desired.
The process according to the invention i6 accordingly as a rule carried out at a temperature of 20 to 200C, preferably at a temperature of 50 to 150~C. The reaction tLme, which is the time required fox reaction o~ the anhydride with the primary and/or secondary 2~mine, i8 as a rule 0.3 to 3 hours. It clearly depends in particular on the reaction temperature and on the degree of reaction sought.
As regards the amount of anhydride, it has proved advan-tageous to employ this in at least the equimolar ratio to the primary and/or secondary amine present. ~he amount of anhydride is thus preferably 1 to 2 mol, and in par-ticular 1.05 to 1.5 mol, per mol of amine to be reacted.
; The amount of primary and secondary amine in the tertiary amine to be treated can be determined, for example, from the known reaction of the tertiary 2~nine product with carbon disulfide and titration of the thioacids formed from the primary and secondary amine.
: . .
The nature of the organic anhydrides to be employed ; according to the invention is not in itself critical. It goes without saying that an anhydride which suits the tertiary amine to be treated will be employed. Possible anhydrides are thus aliphatic, cycloaliphatic or aromatic acid anhydrides. The preferred acid anhydrides are those of the following formula Rl-CO
\
O
in which Rl and R2 are an alkyl radical having 1 to 18 carbon atoms, preferably 2 to 4 carbon atoms, or an alkenyl radical having 2 to 18 carbon atoms, preferably 2 to 4 carbon atoms, or R1 and R2 together are an alkylene s~
~2~ 7 radical having 1 to 10 carbon atoms, preferably 2 to 4 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical. Preferred acid anhydrides are thus those of monocarboxylia acids, preferably saturated (that is to say R1 and R2 are identi-cal and are the alXyl radical mentioned), such as acetic anhydride, propionic anhydride, butyric anhydride and the like, and furthermore those of saturated or unsaturated dicarboxylic acids (that is to say R1 and R2 together are the divalent radical mentioned), such as malonic anhy-dride, succinic anhydride, adipic anhydride, maleic anhydride and the like, and phthalic anhydride. Par-ticularly preferred acid anhydrides are, especially for practica- reasons, acetic anhydride and phthalic anhy-dride.
According to a preferred embodiment, the process accor-ding to the invention is carried out by adding the acid anhydride in at least the stoichiometric (equimolar) amount, based on the primary and secondary amine present (compare above equations), preferably in an amount of 1 to 2 mol, in particular l.OS to 1.5 mol, per mol of primary and secondary amine, to the tertiary amine to be treated, heating the mixture to a temperature of 20 to 200C, preferably 50 to 150C, while stirring, and keeping the mixture at this temperature, likewise while stirring, until the primary and secondary amine pre~ent has reached the lower limit value sought or has been converted completely. The reaction can be carried out under normal pressure or under pressure. Removal of excess acid anhydride and the components formed, that is to say acid and acid amide, can be achieved, if desired, for example, by distillation. The acid and acid anhydride can also be separated off from the tertiary amine, for example, by treating the reaction mixture with alkali (solid or in the form of an aqueous solution) to convert the acid and acid anhydride into the corresponding alkali metal salts. The tertiary amine can now be obtained without problems as the distillate from the mixture now - 6 2~2~7 -present, whereas the metal salts mentioned remain in the bottom product. As already mentioned above, as a rule the acid amide present results in no particular disadvantages in the tertiary amine.
The tertiary amines in ~he context of the present inven-tion are prefexably those of the following formula in which R3 is an alkyl radical or an alkenyl radical having 6 to 24 carbon atoms, preferably 8 to 22 carbon atoms, and R4 and R5, which are preferably identical, are an alkyl~radical having 1 to 4 carbon atoms, preferably the methyl radical. Examples which may be mentioned for R3 are octyl, dodecyl, tetradecyl, stearyl, oleyl, tallow fat alkyl and coconut alkyl.
. :
The abovementioned aminolysis is also shown in the form of an e~uation below, dodecyl alcohol (lauryl alcohol) functioning as the alcohol and dimethylamine as the amine:
` :
Cl2H2s-oH + H-N > C12H25-N + H2O
In addition to thisl main reaction, as is ~known a dig-proportionation of the dimethylamine into, inter alia, monomethylamine, which forms the secondary amine methyl-dodecylamine with the alcohol present, takes place. The undesirable slecondary amines in question accordingly in general correspond to the formula R3-NH-R4, in which R3 and R4 have the meanings given.
The process according to the invention has a number of 2~3~
advantages. It is a simple method which requires little expenditure for partial to complete elimination of primary and secondary amine in a ter~iary amine, it being possible for a tertiary amine which is practically free from the impurities mentioned to be obtained without problems. The reagent used in the process according to the invention, tha~ i8 to ~ay the acid anhydride, is in general readily obtainable and highly reactive. A com-plete conversion can in this way already be achieved under relatively mild reaction conditions. The conversion products formed in the reaction, if they are troublesome at all, can as a rule be removed without problems, so that a tertiary amine which is not only free from primary and secondary amines but also free from other compounds and therefore completely pure can be achieved.
The invention will now be illustrated in more detail by examples.
Example 1 100 g of tertiary amine are to be treated, of the formula Cl214-N(CH3)2, which contained 1.8 g (0.008 mol) of secon-dary amine of the formula Cl2l4-NH-CH3, were introduced into a reaction vessel equipped with a stirrer, reflux condenser and thermometer, and 0.83 g (0.008 mol) of acetic anh~dride was added. The mixture was heated to 100C, while stirring, and kept at this temperature for 1 hour. After the reaction mixture has been cooled, the content of secondary amine was determined. It was only 0.3 parts by weight in 100 parts by weight of tertiary amine.
Examples 2 to 8 These examples were carried out analogously to Example 1.
The tertiary amines to be treated (these are dimethyl-alkylamines, as in Example 1) and their content of secondary amine, the aci~ anhydride employed, the molar J u~ ~ ~t3 ~
ratio of acid anhydride to secondary amine, the reaction temperature, the reaction time and the reduction achieved in the content of secondary amine are summarized in the following table, which also contains Example 1 for simplicity. The following is al~;o mentioned regarding the table, by way of explanation: the alkyl radical of the dimethylalkylamine is shown in column 2 and the values in respect of the content of secondary amine in the third and last column are percentages by weight, based on the tertiary amine to be treated (crude amine).
As regards the examples, it should also be stated that in those where phthalic anhydride is used as the reagent for the secondary amine, the excess phthalic anhydride and the phthalamido acid formed can be removed simply by distillation of the reaction mixture, the phthalic anhydride and the phthalamido acid remaining in the bottom product, because of the boiling point differences, whilst the top product is the pure tertiary amine sought.
In examples where acetic anhydride is used, the excess anhydride and the acetic acid formed are removed in the following manner: a 30~ strength by weight methanolic sodium methylate solution was added to the reaction mixture so that an amount of sodium methylate which corresponds to the molar amount of acetic acid and acetic anhydride present was introduced, after which the mixture was stirred at 70C for 0.25 hours for complete conver-sion of the acetic acid and acetic anhydride into the corresponding sodium salts. Vacuum distillation gave the (acetamide-containing) tertiary amine as the top product, whilst the sodium salts mentioned remained in the bottom product.
2~2~7 . _.
~ ,o,o,,,~
~'o-~O=
..._ '~U 0r~o . . _ ~ ,o ~ ~
~rl ~ ~ 11~ N _I ~ In U~ O ~:
~ W O ~
'1:) 'C1 ~ 'Cl h h h h a ~:~ CO~ ~ ooo ._ . ~ .. . . ..
.~ ~ u u u u 5 u u _ _ ._ E~ ~ ~ ~:
: . .
Claims (7)
1. A process for reducing the content of primary and secondary amine in a tertiary amine, which comprises bringing the tertiary amine to be treated into contact with an organic anhydride until the reduction sought in the content of primary and secondary amine is achieved.
2. The process as claimed in claim 1, wherein the anhy-dride is employed in an amount of 1 to 2 mol per mol of primary and secondary amine.
3. The process as claimed in either of claims 1 and 2, wherein the tertiary amine to be treated and the anhy-dride are brought into contact at a temperature of 20 to 200°C.
4. The process as claimed in either of claims 1 and 2, wherein the tertiary amine to be treated and the anhy-dride are brought into contact at a temperature of 50 to 150°C.
S. The process as claimed in any one of claims 1 to 4, wherein an anhydride of the following formula is employed:
in which R1 and R2 are an alkyl radical having 1 to 18 carbon atoms or an alkenyl radical having 2 to 18 carbon atoms or R1 and R2 together are an alkylene radical having 1 to 10 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical.
in which R1 and R2 are an alkyl radical having 1 to 18 carbon atoms or an alkenyl radical having 2 to 18 carbon atoms or R1 and R2 together are an alkylene radical having 1 to 10 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical.
6. The process as claimed in any one of claims 1 to 4, wherein an anhydride of the following formula is employed:
in which R1 and R2 are an alkyl or alkenyl radical having 2 to 4 carbon atoms or R1 and R2 together are an alkylene radical having 2 to 4 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical.
in which R1 and R2 are an alkyl or alkenyl radical having 2 to 4 carbon atoms or R1 and R2 together are an alkylene radical having 2 to 4 carbon atoms, which can also contain double bonds, or an optionally substituted ortho-phenylene radical.
7. The process as claimed in any one of claims 1 to 4, wherein acetic anhydride or phthalic anhydride is employed as the anhydride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3926765.2 | 1989-08-12 | ||
| DE19893926765 DE3926765A1 (en) | 1989-08-12 | 1989-08-12 | METHOD FOR REDUCING PRIMARY AND SECOND AMINE IN A TERTIA AMINE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2023057A1 true CA2023057A1 (en) | 1991-02-13 |
Family
ID=6387051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2023057 Abandoned CA2023057A1 (en) | 1989-08-12 | 1990-08-10 | Process for reducing the content of primary and secondary amine in a tertiary amine |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0413259A3 (en) |
| JP (1) | JPH0383954A (en) |
| BR (1) | BR9003945A (en) |
| CA (1) | CA2023057A1 (en) |
| DE (1) | DE3926765A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6455710B1 (en) | 2000-12-22 | 2002-09-24 | H. Lundbeck A/S | Method for the preparation of pure citalopram |
| US6509483B2 (en) | 2000-08-18 | 2003-01-21 | H. Lundbeck A/S | Method for the preparation of citalopram |
| US6566540B2 (en) | 1999-10-25 | 2003-05-20 | H. Lundbeck A/S | Method for the preparation of citalopram or S-citalopram |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4140259A1 (en) * | 1991-12-06 | 1993-06-09 | Basf Ag, 6700 Ludwigshafen, De | METHOD FOR PRODUCING TERTIA AMINOXIDES |
| DE4331840A1 (en) * | 1993-09-20 | 1995-03-23 | Basf Ag | Process for the purification of tertiary amines from primary and secondary amines |
| US9809680B2 (en) * | 2015-11-12 | 2017-11-07 | International Business Machines Corporation | Amine scavengers for synthesis of polythioaminals |
| JP7361584B2 (en) * | 2018-12-19 | 2023-10-16 | 高砂香料工業株式会社 | Method for producing amines by reduction of amides |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE536169C (en) * | 1926-08-21 | 1931-10-20 | British Dyestuffs Corp Ltd | Process for the preparation of tertiary aromatic amines from their mixtures with secondary and primary aromatic amines |
| US1695372A (en) * | 1926-11-19 | 1928-12-18 | Silesia Ver Chemischer Fabrike | Process for the separation of mono- and dialkyl derivatives of aromatic amines |
| US1908951A (en) * | 1927-09-23 | 1933-05-16 | Dow Chemical Co | Method of separating alkyl anilines |
| US1890246A (en) * | 1928-04-13 | 1932-12-06 | Dow Chemical Co | Process for separating n-monoalkyl and n-dialkyl aromatic amines of the benzene series |
| DE523603C (en) * | 1928-10-25 | 1931-04-25 | I G Farbenindustrie Akt Ges | Process for the separation of mixtures of secondary and tertiary amines |
| US1991790A (en) * | 1930-10-29 | 1935-02-19 | Du Pont | Process for separating mono-and dialkyl amines of the benzene series |
| US1992111A (en) * | 1931-06-20 | 1935-02-19 | Du Pont | Separation of secondary and tertiary amines |
| DE1032261B (en) * | 1955-03-08 | 1958-06-19 | Leda Chemicals Ltd | Process for separating secondary amines from a mixture containing primary and secondary amines |
-
1989
- 1989-08-12 DE DE19893926765 patent/DE3926765A1/en not_active Withdrawn
-
1990
- 1990-08-09 EP EP19900115304 patent/EP0413259A3/en not_active Withdrawn
- 1990-08-10 CA CA 2023057 patent/CA2023057A1/en not_active Abandoned
- 1990-08-10 JP JP21054690A patent/JPH0383954A/en active Pending
- 1990-08-10 BR BR9003945A patent/BR9003945A/en unknown
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6566540B2 (en) | 1999-10-25 | 2003-05-20 | H. Lundbeck A/S | Method for the preparation of citalopram or S-citalopram |
| US6509483B2 (en) | 2000-08-18 | 2003-01-21 | H. Lundbeck A/S | Method for the preparation of citalopram |
| US6455710B1 (en) | 2000-12-22 | 2002-09-24 | H. Lundbeck A/S | Method for the preparation of pure citalopram |
Also Published As
| Publication number | Publication date |
|---|---|
| BR9003945A (en) | 1991-09-03 |
| DE3926765A1 (en) | 1991-02-14 |
| JPH0383954A (en) | 1991-04-09 |
| EP0413259A3 (en) | 1991-04-03 |
| EP0413259A2 (en) | 1991-02-20 |
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