USH4H - Processs for the preparation of iminodiacetonitrile - Google Patents
Processs for the preparation of iminodiacetonitrile Download PDFInfo
- Publication number
- USH4H USH4H US06/732,791 US73279185A USH4H US H4 H USH4 H US H4H US 73279185 A US73279185 A US 73279185A US H4 H USH4 H US H4H
- Authority
- US
- United States
- Prior art keywords
- sup
- aqueous solution
- hcn
- idan
- formaldehyde
- 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
- BSRDNMMLQYNQQD-UHFFFAOYSA-N iminodiacetonitrile Chemical compound N#CCNCC#N BSRDNMMLQYNQQD-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims description 14
- 230000008569 process Effects 0.000 title claims description 14
- 238000002360 preparation method Methods 0.000 title description 3
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims abstract description 52
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000004312 hexamethylene tetramine Substances 0.000 claims abstract description 27
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims abstract description 27
- 238000010923 batch production Methods 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 239000007864 aqueous solution Substances 0.000 claims description 18
- 239000002253 acid Substances 0.000 claims description 17
- 235000019253 formic acid Nutrition 0.000 claims description 3
- 235000011054 acetic acid Nutrition 0.000 claims 1
- 150000001243 acetic acids Chemical class 0.000 claims 1
- 150000004674 formic acids Chemical class 0.000 claims 1
- 230000003472 neutralizing effect Effects 0.000 claims 1
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 20
- 238000006243 chemical reaction Methods 0.000 description 13
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 11
- 239000006227 byproduct Substances 0.000 description 11
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000010924 continuous production Methods 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 5
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000012736 aqueous medium Substances 0.000 description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N formic acid Substances OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 4
- 239000011541 reaction mixture Substances 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- LTYRAPJYLUPLCI-UHFFFAOYSA-N glycolonitrile Chemical compound OCC#N LTYRAPJYLUPLCI-UHFFFAOYSA-N 0.000 description 2
- JMANVNJQNLATNU-UHFFFAOYSA-N glycolonitrile Natural products N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 2
- NBZBKCUXIYYUSX-UHFFFAOYSA-N iminodiacetic acid Chemical compound OC(=O)CNCC(O)=O NBZBKCUXIYYUSX-UHFFFAOYSA-N 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 101100386054 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) CYS3 gene Proteins 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- -1 alkali metal salt Chemical class 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 101150035983 str1 gene Proteins 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C255/00—Carboxylic acid nitriles
- C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
- C07C255/24—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms containing cyano groups and singly-bound nitrogen atoms, not being further bound to other hetero atoms, bound to the same saturated acyclic carbon skeleton
- C07C255/25—Aminoacetonitriles
Definitions
- the present invention is directed to a process for the preparation of iminodiacetonitrile (IDAN), a valuable intermediate used to prepare compounds such a iminodiacetic acid.
- IDAN iminodiacetonitrile
- IDAN can be obtained by reacting hexamethylenetetramine (HMTA) or its precursors (ammonia and formaldehyde) with HCN.
- HMTA hexamethylenetetramine
- HCN formaldehyde
- IDAN could be prepared in a batch reaction having a yield of about 65% by reacting three moles of HCN, two moles of ammonia, and two moles of formaldehyde in an aqueous solution having a pH of 5.5-6.5. Subsequently, in 1965, Saunders U.S. Pat. No. 3,167,580 taught that IDAN could be produced from the same three reactants in a continuous process carried out at a pH of 7-9 if different mole ratios were used.
- IDAN can be prepared by the reaction of HMTA and HCN in an acidic aqueous medium. In a batch operation, this reaction can be represented as follows: ##STR1## It can be seen that this reaction only succeeds in converting three of the four nitrogens in the HMTA to the desired product, with the remaining nitrogen forming ammonium by-products. The formation of these by-products requires that the acidic pH of the reaction must be maintained by the addition of acid to the reaction mixture. The actual product is thus a slurry of IDAN crystals in a liquor containing dissolved IDAN, HCN, and other organic and ammonium by-products.
- 3,993,681 teaches a batch process wherein HMTA and HCN are reacted in an aqueous solution in the presence of a strong acid at pH 5.5-6.5 and temperatures of 30°-70° C. while maintaining an excess of HCN in the reaction mix.
- Koenig Canadian Patent No. 684,850 prepares IDAN by reacting HMTA (or its precursors) with HCN in aqueous solution and then acidifying with a strong mineral acid.
- HMTA or its precursors
- 3,886,198 discloses a continuous process for the preparation of IDAN by passing a mixture of HMTA, HCN, and a strong acid through a tubular reactor. This continuous process differs from the batch process in that it involves five to seven moles of HCN per mole of HMTA and must be operated at a higher temperature, which is an additional disadvantage.
- An alternate route to IDAN involves the use of glycolonitrile as a reactant. This is disclosed in Gaudette et al. U.S. Pat. No. 3,904,668 wherein an aqueous mixture of HMTA, HCN, and glycolonitrile is continuously passed through a tubular reactor. The process has the advantage of converting all four nitrogens in the HMTA to the IDAN product.
- a pure, colorless iminodiacetonitrile is prepared in high yields in a batch process comprising the addition of HCN to an acidified solution of HMTA while the resulting solution is maintained at a temperature of 20°-90° C. by cooling and the pH at 5.5-6.5 by the addition of formaldehyde.
- IDAN is produced by the reaction of HMTA, HCN, and formaldehyde according to the following equation:
- This reaction has the advantage that all four nitrogens of the HMTA are converted to the IDAN product, unlike prior processes wherein only three of the nitrogens were converted: ##STR2## It is believed that in the reaction of the present invention the additional formaldehyde reacts with the ammonium ion in situ to form hexamine or a hexamine precursor which is subsequently converted to IDAN by reaction with the HCN. The minimization of undesirable ammonium by-products not only increases the IDAN yield but also avoids the need for costly effluent treatment.
- an aqueous solution of HMTA (1.0M) is first preneutralized with acid to a pH of 5.5-6.5 and the temperature adjusted to 0°-60° C. HCN (8-10M) is then added to this solution either all at once or over a period of time (up to about four hours).
- the temperature of the resulting solution is maintained between about 20° C. and about 90° C. with cooling and the pH is maintained between about 5.5-6.5 with the addition of aqueous formaldehyde (2-4M) over a period of from about one to about ten hours.
- the crystalline IDAN product can then be isolated from the aqueous solution after cooling (e.g. by decantation, filtration, or centrifugation).
- the IDAN product can be saponified to form dialkali metal iminodiacetate, by-product ammonia (which is recoverable), and a by-product alkali metal salt.
- the initial pre-neutralization of the aqueous HMTA solution can be carried out with a variety of acids, ranging from weak to strong. Sulfuric, formic, and acetic acid were all used in actual examples but it should be apparent that other acids could readily be substituted. Although sulfuric is preferred for economic reasons, no change in IDAN recovery (about 81%) occurred when formic acid was substituted on a 1:1 equivalent basis for sulfuric. With acetic acid, a slightly lower recovery (76.2%) was obtained when an equivalent amount of acetic was substituted for sulfuric. However, when 1.9 equivalents of acetic acid were used the pH decreased and a recovery of 81.2% was obtained.
- Table I shows the results of a series of experiments carrying out the process of the invention.
- the following experimental procedure was used in each run: A one liter three-necked Morton flask equipped with pH probe, thermometer, condenser, and mechanical stirrer was charged with 1.0M of HMTA (duPont Tech. grade crystal) as a 32.2% aqueous solution. This was neutralized with acid to a pH in the range of 5.5 to 6.0 depending on the run. Hydrogen cyanide (8.15M) was added over 20 minutes after the temperature had been adjusted to 25°-27° C. The temperature profile (Table II) was followed by heating or cooling the flask. The pH was maintained within the desired range by carefully adding an aqueous solution of 44% formaldehyde in small portions.
- Readings of the quantity of formaldehyde used were taken every 10 minutes for the first 11 runs. Thereafter, the average formaldehyde requirement to maintain pH over 10 minutes was calculated and the results used as a guideline in the later runs. In adding the formaldehyde, there was usually a lag of several minutes before a pH reduction was noted, especially at the lower temperatures.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Iminodiacetonitrile is prepared in a batch process comprising the addition of HCN to an acidified solution of hexamethylenetetramine while maintaining the resulting solution at a temperature of 20°-90° C. by cooling and at a pH of 5.5-6.5 by the addition of formaldehyde.
Description
This is a continuation of application Ser. No. 668,118, filed Nov. 5, 1984, which is a continuation-in-part of application Ser. No. 423,510, filed Sept. 27, 1982, now abandoned.
The present invention is directed to a process for the preparation of iminodiacetonitrile (IDAN), a valuable intermediate used to prepare compounds such a iminodiacetic acid.
It is well known that IDAN can be obtained by reacting hexamethylenetetramine (HMTA) or its precursors (ammonia and formaldehyde) with HCN. Eschweiler, Ann., 278, 229-239 (1894); Dubsky et al., Ber., 54, 2659 (1921).
In 1957, Miller U.S. Patent No. 2,794,044 disclosed that IDAN could be prepared in a batch reaction having a yield of about 65% by reacting three moles of HCN, two moles of ammonia, and two moles of formaldehyde in an aqueous solution having a pH of 5.5-6.5. Subsequently, in 1965, Saunders U.S. Pat. No. 3,167,580 taught that IDAN could be produced from the same three reactants in a continuous process carried out at a pH of 7-9 if different mole ratios were used.
It is also known that IDAN can be prepared by the reaction of HMTA and HCN in an acidic aqueous medium. In a batch operation, this reaction can be represented as follows: ##STR1## It can be seen that this reaction only succeeds in converting three of the four nitrogens in the HMTA to the desired product, with the remaining nitrogen forming ammonium by-products. The formation of these by-products requires that the acidic pH of the reaction must be maintained by the addition of acid to the reaction mixture. The actual product is thus a slurry of IDAN crystals in a liquor containing dissolved IDAN, HCN, and other organic and ammonium by-products. These by-products either cannot be separated (which means the liquor cannot be recycled and requires costly effluent treatment) or can only be separated with difficulty. An example is Stutts U.S. Pat. No. 3,412,137 which teaches a batch process for preparing IDAN by reacting an aqueous solution of HMTA with HCN in an aqueous medium buffered with a weak acid (preferably acetic or phosphoric acid) to a pH of 5.5-6.5 at temperatures of 0°-75° C. Cullen U.S. Pat. No. 3,993,681 teaches a batch process wherein HMTA and HCN are reacted in an aqueous solution in the presence of a strong acid at pH 5.5-6.5 and temperatures of 30°-70° C. while maintaining an excess of HCN in the reaction mix. Koenig Canadian Patent No. 684,850 prepares IDAN by reacting HMTA (or its precursors) with HCN in aqueous solution and then acidifying with a strong mineral acid. Similarly, the recent Suchland et al. U.S. Pat. No. 4,307,037 reacts HMTA with HCN in an aqueous medium initially having a pH of 5.5-7.5 and then further acidifying the reaction mixture by 0.5-3.5 pH units by the addition of an acid (preferability sulfuric) at a temperature of 30°-90° C. All of the foregoing references teach batch operations, use the foregoing mole ratio of six moles of HCN to one mole of HMTA, are conducted in an aqueous medium whose acidic pH is maintained by the addition of acid, and are conducted at fairly low temperatures. In contrast, Philbrook et al. U.S. Pat. No. 3,886,198 discloses a continuous process for the preparation of IDAN by passing a mixture of HMTA, HCN, and a strong acid through a tubular reactor. This continuous process differs from the batch process in that it involves five to seven moles of HCN per mole of HMTA and must be operated at a higher temperature, which is an additional disadvantage.
An alternate route to IDAN involves the use of glycolonitrile as a reactant. This is disclosed in Gaudette et al. U.S. Pat. No. 3,904,668 wherein an aqueous mixture of HMTA, HCN, and glycolonitrile is continuously passed through a tubular reactor. The process has the advantage of converting all four nitrogens in the HMTA to the IDAN product.
A more recently developed route involves the addition of formaldehyde, rather than an acid, to maintain the pH of the reaction mixture. A continuous process of this type for the formation of IDAN by the reaction of HMTA, HCN, and formaldehyde is shown in Gaudette et al. U.S. Pat. No. 3,988,360. Like the Gaudette '668 patent, the process theoretically converts all four nitrogens in the HMTA to IDAN, with no formation of ammonium by-product:
(CH.sub.2).sub.6 N.sub.4 +8HCN+2HCHO→4HN(CH.sub.2 CN).sub.2 +2H.sub.2 O
However, because it must be operated at higher temperatures, usually 130°-150° C., this continuous process has been found to suffer from low yields caused by the formation of by-products. It has now been found that batch operation of the reaction described in the Gaudette '360 patent results in a significantly higher yield of a pure, colorless IDAN. It is believed that the reason for this result is the lower temperature at which this batch process may be operated. In contrast, the higher temperature of a continuous process such as that described in the Gaudette '360 patent favors the occurrence of side-reactions which result in the formation of undesirable by-products and color bodies.
In short, the present invention's use of formaldehyde instead of acid as well as the use of lower temperatures both tend to minimize the formation of undesirable by-products and give a higher yield of IDAN.
A pure, colorless iminodiacetonitrile is prepared in high yields in a batch process comprising the addition of HCN to an acidified solution of HMTA while the resulting solution is maintained at a temperature of 20°-90° C. by cooling and the pH at 5.5-6.5 by the addition of formaldehyde.
IDAN is produced by the reaction of HMTA, HCN, and formaldehyde according to the following equation:
(CH.sub.2).sub.6 N.sub.4 +8HCN+2HCHO→4HN(CH.sub.2 CN).sub.2 +2H.sub.2 O
This reaction has the advantage that all four nitrogens of the HMTA are converted to the IDAN product, unlike prior processes wherein only three of the nitrogens were converted: ##STR2## It is believed that in the reaction of the present invention the additional formaldehyde reacts with the ammonium ion in situ to form hexamine or a hexamine precursor which is subsequently converted to IDAN by reaction with the HCN. The minimization of undesirable ammonium by-products not only increases the IDAN yield but also avoids the need for costly effluent treatment.
In carrying out the process of the present invention, an aqueous solution of HMTA (1.0M) is first preneutralized with acid to a pH of 5.5-6.5 and the temperature adjusted to 0°-60° C. HCN (8-10M) is then added to this solution either all at once or over a period of time (up to about four hours). The temperature of the resulting solution is maintained between about 20° C. and about 90° C. with cooling and the pH is maintained between about 5.5-6.5 with the addition of aqueous formaldehyde (2-4M) over a period of from about one to about ten hours. The crystalline IDAN product can then be isolated from the aqueous solution after cooling (e.g. by decantation, filtration, or centrifugation). Alternatively, the IDAN product can be saponified to form dialkali metal iminodiacetate, by-product ammonia (which is recoverable), and a by-product alkali metal salt.
The initial pre-neutralization of the aqueous HMTA solution can be carried out with a variety of acids, ranging from weak to strong. Sulfuric, formic, and acetic acid were all used in actual examples but it should be apparent that other acids could readily be substituted. Although sulfuric is preferred for economic reasons, no change in IDAN recovery (about 81%) occurred when formic acid was substituted on a 1:1 equivalent basis for sulfuric. With acetic acid, a slightly lower recovery (76.2%) was obtained when an equivalent amount of acetic was substituted for sulfuric. However, when 1.9 equivalents of acetic acid were used the pH decreased and a recovery of 81.2% was obtained.
Table I shows the results of a series of experiments carrying out the process of the invention. The following experimental procedure was used in each run: A one liter three-necked Morton flask equipped with pH probe, thermometer, condenser, and mechanical stirrer was charged with 1.0M of HMTA (duPont Tech. grade crystal) as a 32.2% aqueous solution. This was neutralized with acid to a pH in the range of 5.5 to 6.0 depending on the run. Hydrogen cyanide (8.15M) was added over 20 minutes after the temperature had been adjusted to 25°-27° C. The temperature profile (Table II) was followed by heating or cooling the flask. The pH was maintained within the desired range by carefully adding an aqueous solution of 44% formaldehyde in small portions. Readings of the quantity of formaldehyde used were taken every 10 minutes for the first 11 runs. Thereafter, the average formaldehyde requirement to maintain pH over 10 minutes was calculated and the results used as a guideline in the later runs. In adding the formaldehyde, there was usually a lag of several minutes before a pH reduction was noted, especially at the lower temperatures.
It can be seen that in the later runs (after the amount of formaldehyde necessary to maintain a pH was established) recovery of IDAN became consistent at about 81% (based on 4M of IDAN per mole of HMTA). This is about 20-25% better recovery than that achieved in the standard acid-buffered reaction.
TABLE I
__________________________________________________________________________
Acid
Neutral
Reaction
Formaldehyde
IDAN % YLD. on
% YLD
Run #
Eq. pH pH Usage, M
% Yield
N avail.
CH.sub.2 O
__________________________________________________________________________
1 0.326.sup.1
6.00 5.60.sup.4
2.136 77.5 84.4 76.2
2 0.326.sup.1
5.92 5.60.sup.4
3.970 75.6 82.3 60.7
3 0.410.sup.1
5.97 5.75.sup.4
2.039 78.7 87.7 78.3
4 0.359.sup.1
5.80 5.85.sup.4
1.935 73.0 80.2 73.6
5 0.396.sup.1
5.83 5.65.sup.4
1.113 81.5 90.5 91.7
6 0.688.sup.1
5.56 5.60.sup.4
1.168 78.3 94.6 87.4
7 0.500.sup.1
5.80 5.60.sup.4
1.850 80.7 92.2 82.2
8 0.408.sup.1
5.89 5.60.sup.4
Spilled 83.6 93.1 --
9 0.408.sup.1
5.79 5.60.sup.4
2.141 75.4 84.0 74.1
10 0.408.sup.1
5.88 5.60.sup.4
2.397 88.8 98.9 84.6
11 0.396.sup.1
5.85 5.65.sup.4
3.714 Sticky
-- --
12 0.456.sup.1
5.83 5.65.sup.4
2.115 81.6 92.1 80.4
13 0.388.sup.1
5.90 5.64-
1.710 80.2 88.8 83.2
5.90
14 0.388.sup.1
5.83 5.63-
1.941 80.2 88.8 80.8
6.56
15 0.388.sup.1
5.93 5.55-
2.174 80.3 88.9 78.6
5.93
16 0.388.sup.1
5.97 5.60-
2.255 80.8 89.5 78.3
5.97
17 0.388.sup.1
5.76 5.54-
2.279 81.8 90.6 79.0
4.81
18 0.388.sup.1
5.92 5.57-
2.383 81.4 90.1 77.7
5.62
19 0.388.sup.2
5.76 5.80-
2.045 81.7 90.5 81.2
5.94
20 0.388.sup.2
5.96 6.00-
1.913 76.2 84.4 77.0
6.30
21 0.734.sup.3
5.60 5.64-
1.820 81.2 99.5 83.1
5.78
22 0.397.sup.2
5.80 5.65-
1.956 81.1 90.0 81.5
5.80
2.093 81.0%
σ = 0.22
σ = 0.7
Average of 13,14,15,16,18,19 & 22
__________________________________________________________________________
.sup.1 H.sub.2 SO.sub.4
.sup.2 HCO.sub.2 H
.sup.3 CH.sub.3 CO.sub.2 H
.sup.4 Set Point
TABLE II
______________________________________
Time (Min.) Temp. (°C.)
______________________________________
0 28
10 26
20 23.5
30 21
40 21.8
50 22.5
60 23.5
70 25.8
80 27
90 28
100 29
110 30
120 43
130 54
140 66
150 60
160 60
170 60
180 Vacuum cool to 20° C.
over 1 hr.
______________________________________
While the invention has been described in connection with certain preferred conditions, equipment, and embodiments, it is not intended to limit the invention to the particular form set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as defined by the appended claims.
Claims (8)
1. A batch process for the producton of iminodiacetonitrile which comprises:
(a) pre-neutralizing a first aqueous solution of hexamethylenetetramine to a pH between about 5.5 and about 6.5 with an acid and adjusting the temperature to between about 0° C. to about 60° C.;
(b) forming a second aqueous solution by adding HCN to the first aqueous solution while maintaining the temperature between about 20° C. and about 90° C. with cooling and the pH between about 5.5 and 6.5 by the addition of formaldehyde; and
(c) cooling the second aqueous solution and then recovering the iminodiacetonitrile product.
2. A process according to claim 1 in which the acid used to pre-neutralize the first aqueous solution is selected from the group consisting of sulfuric, formic, and acetic acids.
3. A process according to claim 1 in which the HCN is added to the second aqueous solution over a period up to about four hours.
4. A process according to claim 1 in which the formaldehyde is added to the second aqueous solution over a period of between about one and about ten hours.
5. A process according to claim 1 in which the temperature of the second aqueous solution is maintained between about 20° C. and about 75° C.
6. A process according to claim 1 in which the pH of the first aqueous solution is maintained between about 5.8 and about 6.0.
7. A process according to claim 1 in which the pH of the second aqueous solution is maintained between about 5.5 and 6.5.
8. A process according to claim 1 in which for each mole of hexamethylenetetramine about eight moles of HCN and about two moles of formaldehyde are used.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/732,791 USH4H (en) | 1982-09-27 | 1985-05-10 | Processs for the preparation of iminodiacetonitrile |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42351082A | 1982-09-27 | 1982-09-27 | |
| US06/732,791 USH4H (en) | 1982-09-27 | 1985-05-10 | Processs for the preparation of iminodiacetonitrile |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US06668118 Continuation | 1984-11-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USH4H true USH4H (en) | 1985-12-03 |
Family
ID=27026027
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US06/732,791 Abandoned USH4H (en) | 1982-09-27 | 1985-05-10 | Processs for the preparation of iminodiacetonitrile |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USH4H (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4948909A (en) | 1989-08-14 | 1990-08-14 | Monsanto Company | Process for the preparation of iminodiacetonitrile and iminodiacetic acid |
-
1985
- 1985-05-10 US US06/732,791 patent/USH4H/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4948909A (en) | 1989-08-14 | 1990-08-14 | Monsanto Company | Process for the preparation of iminodiacetonitrile and iminodiacetic acid |
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