CA1069898A - Cyanuric acid chlorination with alkali metal hypochlorite - Google Patents
Cyanuric acid chlorination with alkali metal hypochloriteInfo
- Publication number
- CA1069898A CA1069898A CA283,413A CA283413A CA1069898A CA 1069898 A CA1069898 A CA 1069898A CA 283413 A CA283413 A CA 283413A CA 1069898 A CA1069898 A CA 1069898A
- Authority
- CA
- Canada
- Prior art keywords
- alkali metal
- reaction mixture
- hypochlorite
- cyanuric acid
- sodium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/30—Only oxygen atoms
- C07D251/36—Only oxygen atoms having halogen atoms directly attached to ring nitrogen atoms
Abstract
ABSTRACT:
Alkali metal dichloroisocyanurates are instantly and quantitatively prepared by reacting a cyanuric acid with an alkali metal hypochlorite having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2.0 to 2.2, at a pH value of 6.5 to 11.0 and a temperature between 10°C and 55°C.
Alkali metal dichloroisocyanurates are instantly and quantitatively prepared by reacting a cyanuric acid with an alkali metal hypochlorite having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2.0 to 2.2, at a pH value of 6.5 to 11.0 and a temperature between 10°C and 55°C.
Description
~;9~3~8 This invention provides a novel process for chlori-nating cyanuric acid to produce alkali metal dichloroiso-cyanurates without the concommitant formation of nitrogen trichloride or other chloroamines.
Dichloroisocyanurates are well-known materials which are widely used as a source of available chlorine in solid bleaching, sanitizing and detergent compositions. The sodium and potassium salts are the most widely used in laundering compositions because they are very soluble and easily removed by rinsing.
Exemplification of one prior art process for pro-ducing sodium dichloroisocyanurate is disclosed in U.S0 Patent 3,035,056. In this process, sodium dichloroiso-cyanurate is produced by chlorination of trisodiumiso-cyanurate with gaseous chlorine which results in the pro-duction of both sodium dichloroisocyanurate and sodium chloride. In contrast, U.S. Patent 3,035,057 produces potassium dichloroisocyanurate by reacting trichloroiso-cyanuric acid with tripotassium isocyanurate.
U.S. Patent 3,803,144 discloses another process for producing sodium dichloroisocyanurate by chlorinating ;
cyanuric acid with sufficient chlorine and sodium hypo-chlorite or sodium hydroxide to produce solid dichloroiso-cyanuric acid at a pH value of from 1.5 to 3.5 and at a -1- . ~
., :. ~ :.
:., ,. :
" . .
temperature from 5 to 45~C wherein the mole ratio of said alkali to cyanuric acid is from 1.90:1 to 2.1:1 in a first aqueous medium, and neutralizing the solid dichloroiso-cyanuric acid with sodium hydroxide in a second aqueous medium at a pH rom 6 to 7 to form sodium dichloroiso-cyanurate dihydrate particles which are subsequently separated and dried.
While these processes are effective for producing sodium ~r potassium dichloroisocyan~ra~es, they require carefully controlled procedures for carrying out the chlorination and neutralization reactions to maximize pro duct yields as well as to minimize the production of dan-gerous side products, such as nitrogen trichloride.
Slight changes in the amount of chlorinating material and/or the alkali necessary to carry out the reaction can cause rapid changes in pH values which changes often result in cyanuric acid ring degradation.
In accordance with the present invention, alkali metal dichloroisocyanurates are produced directly from cyanuric acid without the need for separate chlorination and neutralization reactions by mixing in water sufficient amounts of cyanuric acid and an alkali metal hypochlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based on the weight of the mixture, said mixture having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2,0 to 2.2, and a pH value of 6 . 5 to ll.0; heating the reaction mixture at a temperature between 10 and 55~C to form chlorinated isocyanurate~; adjusting the pH value of --2~
:,,~,................................. .
,~ ' :::, :, ' '.', . ' ' ',: ' ~;g8~
the heated reaction mixture to between 6.0 and 8.0 with a mineral acid solution to neutralize alkali metal hydroxides formed during the reaction; cooling the neutralized reaction mixture to precipitate the alkali metal dichloro-isocyanurate; and recovering the alkali metal dichloroiso-cyanurate from the solution The process of the present invention permits the for-mation of alkali metal dichloroisocyanurates from cyanuric acid in a commercially simple and efficient manner with essentially no triazine ring decomposition and little or no nitrogen trichloride or other chloroamine formation. It also permits the quantitative recovery of alkali metal dichloroisocyanurates with exceptionally high purities in relatively short periods of time.
In the process of the invention, ~ufficient amounts of cyanuric acid are mixed with an alkali metal hypo-chlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based upon the weight of the reaction mixture.
The cyanuric acid employed is preferably purified cyanuric acid containing less than about 2% amino substituted tri-azine impurities, such as melamine, ammeline, ammelide, ammeline:ammelide complex, and cyanuric acid:melamine com-plex, and preferably contains less than 0.5~ amino sub-stituted triazine impurities. From a commercial stand-point, reaction mixture concentrations below about 6 weight % are not economical in view of the small amount of material being treated. Reaction mixture concen-trations above 20 weight ~ are difficult to handle and ,.. ~ , , .
.
. - ~. . .
10~8~3B
accordingly are ~ot advisable. Preferably, the concen-tration is from 10 to 20 weight ~ based upon the weight of the reaction mixture.
The cyanuric acid reaction mixture is obtained by either mixing dry cyanuric acid and the alkali metal hypo-chlorite compound in water or mixing aqueous solutions of one or both of these materials together.
The alkali metal hypochlorites employed in this inven-tion either singly or in combination are preferably sodium hypochlorite, lithium hypochlorite and potassium hypo-chlorite, however, other equivalent hypochlorites may also be employed. Some of these latter hypochlorites include magnesium hypochlorite and calcium hypochlorite.
To achieve complete conversion of the cyanuric acid to the alkali metal dichloroisocyanurates, sufficient alkali metal hypochlorite must be added to completely N-chlorinate the triazine molecule. A mole ratio of cyanuric acid to alkali metal hypochlorite of 1:2.0 to 2.2 gives high yields of essentially pure alkali metal dichloroisocyanurates. Optimum results are obtained by employing a mole ratio of cyanuric acid to alkali metal hypochlorite of 1:2.0 to 2.05. Any stoichiometry less than that stated results in the undesirable formation of mixtures containing cyanuric acid and the alkali metal dichloroisocyanurates, which mixtures require extensive purification procedures to prepare substantially pure alkali metal dichloroisocyanurates.
The reaction mixture is preferably heated to a .. . .
.. . .. .. . . . . .
.
, : .
~Q~3~8 temperature between 10 and 55C. Since this i5 a mildly exoth~rmic reaction, temperatur~ control of the r~action media is easily achieved by conventional external cooling means. The best mode contemplated for practicing this invention, which provides the highest yields, is with reaction temperatures between 20 and 30~C. Since the residence time in the reactor required for the reaction to reach completion is extremely short, temperatures above 30C may be employed with little or no decomposition of the alkali metal dichloroisocyanurates.
Conversion of cyanuric acid into the alkali metal dichloroisocyanurate is effected at pH values from 6.5 to 11.0 with maximum conversions being achieved at p~ values between 6.5 and 8Ø Within these operating conditions, cyanuric acid is instantly and quantitatively converted to alkali metal dichloroisocyanurate. Since there is essen-tially no triazine ring decomposition, little or no nitrogen trichloride or other chloroamine by-products are formed.
- Mixing of the cyanuric acid and alkali metal hypo-chlorites to form the resulting reaction mixture, which may be a slurry, as well a~ the heating are achieved by conventional means and procedures. Mixing and heating may be done separately or carried ouk in a single stage, the latter being preferred since the reaction requires relatively short reaction times under operating conditions to instantly and quantitatively convert the cyanuric acid into alkali metal dichloroisocyanurates.
..
-S~
: .
:, . . . , : :
,. . .
.. . . . . .
"~"' ''" ; ' ' ' ' ., ., ,- : ~ . :,, " ~ ......... ... .
10~898 The reaction between cyanuric acid and ~he alkali metal hypochlorite is extremely rapid under operating con-ditions with complete conversions being achieved in a matter of seconds. High, commercially valuable yields are obtained with residence times in the reactor up to 5 minutes and preferably up to 2 minutes. These reaction times can be achieved with conventional reactors. The combination of high yields, short residence times and the ability to operate with a single sta~ process results in a commercial process which can employ a single, small, pipelike reactor with high through-put~ A pipe reactor is an elongated tubular reaction chamber wherein the feed enters the reactor in one end and product exits out of the other end. The reaction takes place within the tube which is heated by external sources. Use of pipe reactors eliminates most of the heat removal and operating problems of the prior art processes and results in a substantial reduction in the amount of capital equipment needed.
When the reaction is complete, the pH value of the heated reaction mixture must be adjusted to between 6.0 and 8.0,-and preferably between 6.5 and 7.5. If the pH
value of the reaction mixture were permitted to remain at pH values ahove 10.0 for any substantial period of time following the reaction, which pH values form during the reaction, triazine ring degradation substantially increases. The addition of a mineral acid to the heated reaction mixture aids in lowering the pH value to the optimum equilibrium value of the alkali metal ., ~6--'~, .' ' ' ' ~
, , ' ' . .
~o~
dichlorolsocyanurate and neutralizes the alkali metal hydroxide formed during the reaction. The mineral acid is preferably employed as a dilute mineral acid solution con-taining from 20% to 60~ by weight mineral acid dispersed in water. Mineral acid concentrations above 60% by weight should not be employed since these concentrations may cause an exothermic acidification reaction which converts the alkali metal dichloroisocyanurate into dichloroiso-cyanuric acid. Mineral acid concentrations below 20% are not preferred since they introduce large quantities of water during neutralization which decreases process efficiency and increases the quantities of water that must be processed. Any mineral acid which i5 compatible with the reactants in the system may be employed, with pre-ferred mineral acids being selected from the group con-sisting of sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid, with sulfuric acid being most preferred.
When employing sodium hypochlorite as the alkali metal hypochlorite, the following theoretical chemical reactions occur:
C3N303~3 ~ 2NaOCl = NaC3N303Cl2 + NaOH + H2 NaOH + HX = NaX + H20 Following neutralization, the reaction mixture is cooled by conventional means to precipitate additional ~-alkali metal dichloroisocyanurate crystals. Preferably, the reaction mixture is rapidly cooled in less than 30 ~: , . : , .
, , . .: . . . .
, . ~
:' ' ' i.; ' ~", , ~ , , ~ .
'. :.: ' ' ' , .
.: , 38~3 minutes to below 20C and preferably to below 10C.
Cooling is essential to prevent triazine ring degradation and to lower the solubility of the alkali metal dichloro-isocyanurate in the reaction mediurn. The precipitated crystalline product is recovered by conventional liquid-solid sepa~atory means.
The recovered products may then be optionally dried and stored. Drying may be carried out in any conventional manner to remove residual moisture and to produce a free-flowing crystalline product. These procedures are well known in the art and do not constitute a part of the invention.
The invention will be better understood from a con-sideration of the following examples. The examples are given to further illustrate the invention. All per-centages given are based on weight unless otherwise indicated.
Example I
Run l A 6.45 gram (0.05 mole) sample of purified cyanuric acid a~saying 99.8~ cyanuric acid was added to 54.6 grams of an aqueous solution containing 7.44 grams (0.10 mole) of sodium hypochlorite to prepare a 10.56 weight %
cyanuric acid reaction mixture. The aqueous reaction mixture had a pH value of a . 6 and a temperature of 24C.
The cyanuric acid went into solution almost immediately upon its addition to the reaction mixture, the pH value rose to lO.l and the temperature rose to and was main-,~,, .
_~_ .~,.~,, , ~ . , .
. . .
.
.
"' ''- ~ , ' ~'''' ~ , .
~tj~
tained at 26-27C for 30 seconds. After 30 ~econds, the reaction mixture pH value was adjusted to 6.5 to 7.0 by addition of small amounts of dilute sulfuric acid where-upon the reaction vessel was quenched in an ice bath and cooled to 10C within two minutes. The reaction vessel was remove~ from the ice bath and the crystallized pre-cipitate was filtered, washed and dried at 40C to remove surface water, The precipitate was identified as sub-stanti~lly pure sodium dichloroisocyanurate dihydrate.
The total yield was 12.8 grams which is equivalent to 100~ recovery based on starting triazines.
Example II
Runs 2 to 13 The procedure of Example I was repeated except that the process conditions were modified as reported in Table I, In all runs, the reaction temperature was maintained at 27C and the cyanuric acid to sodium hypo-chlorite mole ratio was 1:2Ø
The results set forth in Table I demonstrate that at reaction pH values from 6.5 to 8.0, essentially quanti-tative yields are obtained over the reaction time periods.
Example III
Run~ I4 to I9, Comparativ_ ~uns A & B
The procedure of Example I was repeated except that the process conditions were modified as reported in Table II.
The results of runs 14 to 19 reported in Table II
~, ~
_g_ : .
: ~ ' ' . :
.- ' ., ~ 89 ~
demonstrate that complete conver~ion of cyanuric acid is achieved by employing stoichiometric amounts of sodium hypochlorite. When less than stoichiometric amounts are employed, the degree of chlorination is drastically altered as demonstrated in Comparative Runs A and B.
Runs 14 and 15 demonstrate that longer reaction times at elevated temperatures result in reduced triazine recoveries.
Runs 20 and 21 The procedure of Example I was repeated except that pota~sium hypochlorite ~Run 20) and lithium hypochlorite (Run 21) were employed for sodium hypochloriteO The results are reported in Table III.
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Dichloroisocyanurates are well-known materials which are widely used as a source of available chlorine in solid bleaching, sanitizing and detergent compositions. The sodium and potassium salts are the most widely used in laundering compositions because they are very soluble and easily removed by rinsing.
Exemplification of one prior art process for pro-ducing sodium dichloroisocyanurate is disclosed in U.S0 Patent 3,035,056. In this process, sodium dichloroiso-cyanurate is produced by chlorination of trisodiumiso-cyanurate with gaseous chlorine which results in the pro-duction of both sodium dichloroisocyanurate and sodium chloride. In contrast, U.S. Patent 3,035,057 produces potassium dichloroisocyanurate by reacting trichloroiso-cyanuric acid with tripotassium isocyanurate.
U.S. Patent 3,803,144 discloses another process for producing sodium dichloroisocyanurate by chlorinating ;
cyanuric acid with sufficient chlorine and sodium hypo-chlorite or sodium hydroxide to produce solid dichloroiso-cyanuric acid at a pH value of from 1.5 to 3.5 and at a -1- . ~
., :. ~ :.
:., ,. :
" . .
temperature from 5 to 45~C wherein the mole ratio of said alkali to cyanuric acid is from 1.90:1 to 2.1:1 in a first aqueous medium, and neutralizing the solid dichloroiso-cyanuric acid with sodium hydroxide in a second aqueous medium at a pH rom 6 to 7 to form sodium dichloroiso-cyanurate dihydrate particles which are subsequently separated and dried.
While these processes are effective for producing sodium ~r potassium dichloroisocyan~ra~es, they require carefully controlled procedures for carrying out the chlorination and neutralization reactions to maximize pro duct yields as well as to minimize the production of dan-gerous side products, such as nitrogen trichloride.
Slight changes in the amount of chlorinating material and/or the alkali necessary to carry out the reaction can cause rapid changes in pH values which changes often result in cyanuric acid ring degradation.
In accordance with the present invention, alkali metal dichloroisocyanurates are produced directly from cyanuric acid without the need for separate chlorination and neutralization reactions by mixing in water sufficient amounts of cyanuric acid and an alkali metal hypochlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based on the weight of the mixture, said mixture having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2,0 to 2.2, and a pH value of 6 . 5 to ll.0; heating the reaction mixture at a temperature between 10 and 55~C to form chlorinated isocyanurate~; adjusting the pH value of --2~
:,,~,................................. .
,~ ' :::, :, ' '.', . ' ' ',: ' ~;g8~
the heated reaction mixture to between 6.0 and 8.0 with a mineral acid solution to neutralize alkali metal hydroxides formed during the reaction; cooling the neutralized reaction mixture to precipitate the alkali metal dichloro-isocyanurate; and recovering the alkali metal dichloroiso-cyanurate from the solution The process of the present invention permits the for-mation of alkali metal dichloroisocyanurates from cyanuric acid in a commercially simple and efficient manner with essentially no triazine ring decomposition and little or no nitrogen trichloride or other chloroamine formation. It also permits the quantitative recovery of alkali metal dichloroisocyanurates with exceptionally high purities in relatively short periods of time.
In the process of the invention, ~ufficient amounts of cyanuric acid are mixed with an alkali metal hypo-chlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based upon the weight of the reaction mixture.
The cyanuric acid employed is preferably purified cyanuric acid containing less than about 2% amino substituted tri-azine impurities, such as melamine, ammeline, ammelide, ammeline:ammelide complex, and cyanuric acid:melamine com-plex, and preferably contains less than 0.5~ amino sub-stituted triazine impurities. From a commercial stand-point, reaction mixture concentrations below about 6 weight % are not economical in view of the small amount of material being treated. Reaction mixture concen-trations above 20 weight ~ are difficult to handle and ,.. ~ , , .
.
. - ~. . .
10~8~3B
accordingly are ~ot advisable. Preferably, the concen-tration is from 10 to 20 weight ~ based upon the weight of the reaction mixture.
The cyanuric acid reaction mixture is obtained by either mixing dry cyanuric acid and the alkali metal hypo-chlorite compound in water or mixing aqueous solutions of one or both of these materials together.
The alkali metal hypochlorites employed in this inven-tion either singly or in combination are preferably sodium hypochlorite, lithium hypochlorite and potassium hypo-chlorite, however, other equivalent hypochlorites may also be employed. Some of these latter hypochlorites include magnesium hypochlorite and calcium hypochlorite.
To achieve complete conversion of the cyanuric acid to the alkali metal dichloroisocyanurates, sufficient alkali metal hypochlorite must be added to completely N-chlorinate the triazine molecule. A mole ratio of cyanuric acid to alkali metal hypochlorite of 1:2.0 to 2.2 gives high yields of essentially pure alkali metal dichloroisocyanurates. Optimum results are obtained by employing a mole ratio of cyanuric acid to alkali metal hypochlorite of 1:2.0 to 2.05. Any stoichiometry less than that stated results in the undesirable formation of mixtures containing cyanuric acid and the alkali metal dichloroisocyanurates, which mixtures require extensive purification procedures to prepare substantially pure alkali metal dichloroisocyanurates.
The reaction mixture is preferably heated to a .. . .
.. . .. .. . . . . .
.
, : .
~Q~3~8 temperature between 10 and 55C. Since this i5 a mildly exoth~rmic reaction, temperatur~ control of the r~action media is easily achieved by conventional external cooling means. The best mode contemplated for practicing this invention, which provides the highest yields, is with reaction temperatures between 20 and 30~C. Since the residence time in the reactor required for the reaction to reach completion is extremely short, temperatures above 30C may be employed with little or no decomposition of the alkali metal dichloroisocyanurates.
Conversion of cyanuric acid into the alkali metal dichloroisocyanurate is effected at pH values from 6.5 to 11.0 with maximum conversions being achieved at p~ values between 6.5 and 8Ø Within these operating conditions, cyanuric acid is instantly and quantitatively converted to alkali metal dichloroisocyanurate. Since there is essen-tially no triazine ring decomposition, little or no nitrogen trichloride or other chloroamine by-products are formed.
- Mixing of the cyanuric acid and alkali metal hypo-chlorites to form the resulting reaction mixture, which may be a slurry, as well a~ the heating are achieved by conventional means and procedures. Mixing and heating may be done separately or carried ouk in a single stage, the latter being preferred since the reaction requires relatively short reaction times under operating conditions to instantly and quantitatively convert the cyanuric acid into alkali metal dichloroisocyanurates.
..
-S~
: .
:, . . . , : :
,. . .
.. . . . . .
"~"' ''" ; ' ' ' ' ., ., ,- : ~ . :,, " ~ ......... ... .
10~898 The reaction between cyanuric acid and ~he alkali metal hypochlorite is extremely rapid under operating con-ditions with complete conversions being achieved in a matter of seconds. High, commercially valuable yields are obtained with residence times in the reactor up to 5 minutes and preferably up to 2 minutes. These reaction times can be achieved with conventional reactors. The combination of high yields, short residence times and the ability to operate with a single sta~ process results in a commercial process which can employ a single, small, pipelike reactor with high through-put~ A pipe reactor is an elongated tubular reaction chamber wherein the feed enters the reactor in one end and product exits out of the other end. The reaction takes place within the tube which is heated by external sources. Use of pipe reactors eliminates most of the heat removal and operating problems of the prior art processes and results in a substantial reduction in the amount of capital equipment needed.
When the reaction is complete, the pH value of the heated reaction mixture must be adjusted to between 6.0 and 8.0,-and preferably between 6.5 and 7.5. If the pH
value of the reaction mixture were permitted to remain at pH values ahove 10.0 for any substantial period of time following the reaction, which pH values form during the reaction, triazine ring degradation substantially increases. The addition of a mineral acid to the heated reaction mixture aids in lowering the pH value to the optimum equilibrium value of the alkali metal ., ~6--'~, .' ' ' ' ~
, , ' ' . .
~o~
dichlorolsocyanurate and neutralizes the alkali metal hydroxide formed during the reaction. The mineral acid is preferably employed as a dilute mineral acid solution con-taining from 20% to 60~ by weight mineral acid dispersed in water. Mineral acid concentrations above 60% by weight should not be employed since these concentrations may cause an exothermic acidification reaction which converts the alkali metal dichloroisocyanurate into dichloroiso-cyanuric acid. Mineral acid concentrations below 20% are not preferred since they introduce large quantities of water during neutralization which decreases process efficiency and increases the quantities of water that must be processed. Any mineral acid which i5 compatible with the reactants in the system may be employed, with pre-ferred mineral acids being selected from the group con-sisting of sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid, with sulfuric acid being most preferred.
When employing sodium hypochlorite as the alkali metal hypochlorite, the following theoretical chemical reactions occur:
C3N303~3 ~ 2NaOCl = NaC3N303Cl2 + NaOH + H2 NaOH + HX = NaX + H20 Following neutralization, the reaction mixture is cooled by conventional means to precipitate additional ~-alkali metal dichloroisocyanurate crystals. Preferably, the reaction mixture is rapidly cooled in less than 30 ~: , . : , .
, , . .: . . . .
, . ~
:' ' ' i.; ' ~", , ~ , , ~ .
'. :.: ' ' ' , .
.: , 38~3 minutes to below 20C and preferably to below 10C.
Cooling is essential to prevent triazine ring degradation and to lower the solubility of the alkali metal dichloro-isocyanurate in the reaction mediurn. The precipitated crystalline product is recovered by conventional liquid-solid sepa~atory means.
The recovered products may then be optionally dried and stored. Drying may be carried out in any conventional manner to remove residual moisture and to produce a free-flowing crystalline product. These procedures are well known in the art and do not constitute a part of the invention.
The invention will be better understood from a con-sideration of the following examples. The examples are given to further illustrate the invention. All per-centages given are based on weight unless otherwise indicated.
Example I
Run l A 6.45 gram (0.05 mole) sample of purified cyanuric acid a~saying 99.8~ cyanuric acid was added to 54.6 grams of an aqueous solution containing 7.44 grams (0.10 mole) of sodium hypochlorite to prepare a 10.56 weight %
cyanuric acid reaction mixture. The aqueous reaction mixture had a pH value of a . 6 and a temperature of 24C.
The cyanuric acid went into solution almost immediately upon its addition to the reaction mixture, the pH value rose to lO.l and the temperature rose to and was main-,~,, .
_~_ .~,.~,, , ~ . , .
. . .
.
.
"' ''- ~ , ' ~'''' ~ , .
~tj~
tained at 26-27C for 30 seconds. After 30 ~econds, the reaction mixture pH value was adjusted to 6.5 to 7.0 by addition of small amounts of dilute sulfuric acid where-upon the reaction vessel was quenched in an ice bath and cooled to 10C within two minutes. The reaction vessel was remove~ from the ice bath and the crystallized pre-cipitate was filtered, washed and dried at 40C to remove surface water, The precipitate was identified as sub-stanti~lly pure sodium dichloroisocyanurate dihydrate.
The total yield was 12.8 grams which is equivalent to 100~ recovery based on starting triazines.
Example II
Runs 2 to 13 The procedure of Example I was repeated except that the process conditions were modified as reported in Table I, In all runs, the reaction temperature was maintained at 27C and the cyanuric acid to sodium hypo-chlorite mole ratio was 1:2Ø
The results set forth in Table I demonstrate that at reaction pH values from 6.5 to 8.0, essentially quanti-tative yields are obtained over the reaction time periods.
Example III
Run~ I4 to I9, Comparativ_ ~uns A & B
The procedure of Example I was repeated except that the process conditions were modified as reported in Table II.
The results of runs 14 to 19 reported in Table II
~, ~
_g_ : .
: ~ ' ' . :
.- ' ., ~ 89 ~
demonstrate that complete conver~ion of cyanuric acid is achieved by employing stoichiometric amounts of sodium hypochlorite. When less than stoichiometric amounts are employed, the degree of chlorination is drastically altered as demonstrated in Comparative Runs A and B.
Runs 14 and 15 demonstrate that longer reaction times at elevated temperatures result in reduced triazine recoveries.
Runs 20 and 21 The procedure of Example I was repeated except that pota~sium hypochlorite ~Run 20) and lithium hypochlorite (Run 21) were employed for sodium hypochloriteO The results are reported in Table III.
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Claims (12)
1. A process for producing an alkali metal dichloro-isocyanurate, characterized by:
a) mixing in water sufficient amounts of cyanuric acid and an alkali metal hypochlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based on the weight of the mixture, said reaction mixture having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2.0 to 2.2, and a pH value of 6.5 to 11.0;
b) heating the reaction mixture to a temperature between 10° and 55°C to form alkali metal dichloroiso-cyanurate;
c) adjusting the pH value of the heated reaction mixture to between 6.0 and 8.0 with a mineral acid solution to neutralize alkali metal hydroxide products formed during the reaction;
d) cooling the neutralized reaction mixture to precipitate the alkali metal dichloroisocyanurate; and e) recovering the alkali metal dichloroiso-cyanurate product.
a) mixing in water sufficient amounts of cyanuric acid and an alkali metal hypochlorite to form a 6 to 20 weight % cyanuric acid reaction mixture based on the weight of the mixture, said reaction mixture having a cyanuric acid to alkali metal hypochlorite mole ratio of 1:2.0 to 2.2, and a pH value of 6.5 to 11.0;
b) heating the reaction mixture to a temperature between 10° and 55°C to form alkali metal dichloroiso-cyanurate;
c) adjusting the pH value of the heated reaction mixture to between 6.0 and 8.0 with a mineral acid solution to neutralize alkali metal hydroxide products formed during the reaction;
d) cooling the neutralized reaction mixture to precipitate the alkali metal dichloroisocyanurate; and e) recovering the alkali metal dichloroiso-cyanurate product.
2. The process of claim 1 characterized in that the alkali metal hypochlorite, are selected from the group con-sisting of sodium hypochlorite, lithium hypochlorite and potassium hypochlorite.
3. The process of claim 1 characterized in that the reaction mixture of step a) contains 10 to 20 weight %
cyanuric acid based on the weight of the reaction mixture.
cyanuric acid based on the weight of the reaction mixture.
4. The process of claim 1 characterized in that the cyanuric acid to alkali metal hypochlorite mole ratio is 1:2.0 to 2.05.
5. The process of claim 1 characterized in that the pH value of step a) is maintained between 6.5 and 8Ø
6. The process of claim 1 characterized in that the reaction mixture is heated and maintained between 20° and 30°C.
7. The process of claim 1 characterized in that the alkali metal hypochlorite is sodium hypochlorite and the alkali metal dichloroisocyanurate is sodium dichloroiso-cyanurate dihydrate.
8. The process of claim 1 characterized in that the alkali metal hypochlorite is lithium hypochlorite and the alkali metal dichloroisocyanurate is lithium dichloro-isocyanurate.
9. The process of claim 1 characterized in that the alkali metal hypochlorite is potassium hypochlorite and the alkali metal dichloroisocyanurate is potassium dichloroisocyanurate.
10. The process of claim 1 characterized in that mixing step a) and heating step b) are carried out in a single stage.
11. The process of claim 1 characterized in that the pH value of the heated reaction mixture in step c) is adjusted to between 6.5 and 7.5 with a mineral acid.
12. A process for producing sodium dichloroiso-cyanurate dihydrate which comprises:
a) mixing in water sufficient amounts of cyanuric acid and sodium hypochlorite to form a 10 to 20 weight % cyanuric acid reaction mixture based on weight of the mixture, said reaction mixture having a cyanuric acid to sodium hypochlorite mole ratio of 1:2.0 to 2.05 and a pH value of 6.5 to 8.0;
b) heating the reaction mixture to a tempera-ture between 20° to 30°C to form sodium dichloroiso-cyanurate dihydrate;
c) adjusting the pH value of the heated reaction mixture to between 6.5 and 7.5 with a mineral acid solution to neutralize the sodium hydroxide formed during the reaction;
d) cooling the neutralized reaction mixture to precipitate the sodium dichloroisocyanurate dihydrate, and e) recovering the sodium dichloroisocyanurate dihydrate.
a) mixing in water sufficient amounts of cyanuric acid and sodium hypochlorite to form a 10 to 20 weight % cyanuric acid reaction mixture based on weight of the mixture, said reaction mixture having a cyanuric acid to sodium hypochlorite mole ratio of 1:2.0 to 2.05 and a pH value of 6.5 to 8.0;
b) heating the reaction mixture to a tempera-ture between 20° to 30°C to form sodium dichloroiso-cyanurate dihydrate;
c) adjusting the pH value of the heated reaction mixture to between 6.5 and 7.5 with a mineral acid solution to neutralize the sodium hydroxide formed during the reaction;
d) cooling the neutralized reaction mixture to precipitate the sodium dichloroisocyanurate dihydrate, and e) recovering the sodium dichloroisocyanurate dihydrate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72129576A | 1976-09-08 | 1976-09-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069898A true CA1069898A (en) | 1980-01-15 |
Family
ID=24897370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,413A Expired CA1069898A (en) | 1976-09-08 | 1977-07-25 | Cyanuric acid chlorination with alkali metal hypochlorite |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5334786A (en) |
| BE (1) | BE858437A (en) |
| CA (1) | CA1069898A (en) |
| DE (1) | DE2735025A1 (en) |
| FR (1) | FR2364208A1 (en) |
| GB (1) | GB1537935A (en) |
| IT (1) | IT1085158B (en) |
| NL (1) | NL7708688A (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3668204A (en) * | 1970-08-21 | 1972-06-06 | Fmc Corp | Chlorination of cyanuric acid |
| US3712891A (en) * | 1971-07-21 | 1973-01-23 | Fmc Corp | Chlorination of cyanuric acid |
| US3806507A (en) * | 1972-07-20 | 1974-04-23 | Olin Corp | Chlorocyanuric acid manufacture |
| US4024140A (en) * | 1976-05-19 | 1977-05-17 | Olin Corporation | Production of alkali metal salts of dichloroisocyanuric acid |
-
1977
- 1977-07-25 CA CA283,413A patent/CA1069898A/en not_active Expired
- 1977-08-03 DE DE19772735025 patent/DE2735025A1/en not_active Withdrawn
- 1977-08-05 NL NL7708688A patent/NL7708688A/en not_active Application Discontinuation
- 1977-08-25 IT IT2697577A patent/IT1085158B/en active
- 1977-08-26 JP JP10179277A patent/JPS5334786A/en active Pending
- 1977-09-05 FR FR7726850A patent/FR2364208A1/en not_active Withdrawn
- 1977-09-06 BE BE180699A patent/BE858437A/en unknown
- 1977-09-07 GB GB3724777A patent/GB1537935A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT1085158B (en) | 1985-05-28 |
| BE858437A (en) | 1978-03-06 |
| FR2364208A1 (en) | 1978-04-07 |
| NL7708688A (en) | 1978-03-10 |
| DE2735025A1 (en) | 1978-03-09 |
| JPS5334786A (en) | 1978-03-31 |
| GB1537935A (en) | 1979-01-10 |
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