T h e life study run was terminated a t 700 hours of continuous operation. The over-all conversion of dipropylene glycol to dimethylmorpholine was 65% and the over-all yield was 79%. Even when terminated, the catalyst was still active, giving a conversion of over 60%. The production of dimethylmorpholine was 70 grams per gram of catalyst, and obviously the catalyst still had a great deal of additional production capacity.
(2) Langdon, W. K., Jaul, Ernest, Levis, W. W., Jr. (to Wyandotte Chemicals), Zbid., 3,154,544 (1964). ( 3 ) Langdon, W. K., Levis, W. W., Jr. (to Wyandotte Chemicals), Zbid., 2,911,407 (Nov. 3, 1959).
literature Cited
(4) Langdon, W. K., Levis, W. W., Jr., Jackson, D. R., Znd. Eng. Chem. Process Design Develop. 1, 153-6 (1962). (5) Langdon, W. K., Levis, W. W., Jr., Jackson, D. R., Cenker, Moses, Baxter, G. E., IND.ENG.CHEM.PROD.RES. DEVELOP. 3, 8-11 (1964). (6) Sexton, A. R., Britton, E. C., J . Am. Chem. Sac. 75, 4357 (1953). RECEIVED for review February 14, 1966 ACCEPTEDJuly 5, 1966
(1) Jaul, Ernest, Langdon, W. K., Levis, W. W., Jr. (to Wyandotte Chemicals), U. S. Patent 2,928,877 (March 15, 1960).
Division of Industrial and Engineering Chemistry, 150th Meeting, ACS, September 1966, Atlantic City, N. J.
ALKALINE HYDROLYSIS OF SODIUM TRIMETAPHOSPHATE IN CONCENTRATED SOLUTIONS AND ITS ROLE IN BUILT D ET ERGEN T S C . Y . SHEN Inorganic Chemicals Division, Monsanto Go., St. Louis, Ma. The conversion rate and mechanism of sodium trimetaphosphate to sodium tripolyphosphate in concentrated alkaline solutions were determined. For most detergent slurries, the conversion rate is fast enough so that sodium trimetaphosphate can be advantageously used as a source of sodium tripolyphosphate. Sodium trimeta phosphate seems to offer a new technology in processing built detergents.
ODIUM
trimetaphosphate, (NaP03)3 or NaPO3-I, differs
S from other sodium meta- and/or polyphosphates in that its anion is a unique six-membered ring and it is a salt of a strong acid and a strong base (72). Since it does not have the desirable property of sequestering or forming soluble complexes with calcium or magnesium in a water solution ( Z ) , or the buffering action to maintain the desired p H of the solution, sodium trimetaphosphate heretofore has been considered as an inert salt, and for many years remained a laboratory curiosity. Therefore, sodium tripolyphosphate producers usually kept the amount of sodium trimetaphosphate in their tripolyphosphate products a t a minimum. O n the other hand, earlier publications (7, 4) indicated that the trimetaphosphate can be hydrolyzed into sodium tripolyphosphate in a dilute alkaline solution. Whether sodium trimetaphosphate should be considered as a valuable ingredient in a phosphate builder of a synthetic detergent depends on its rate of conversion to tripolyphosphate under practical conditions. Kinetic studies on the hydrolysis of sodium trimetaphosphate have been reported by several investigators (3,5, 6, 7). Their techniques, results, and conclusions differ considerably. T o facilitate their studies, one or more of the following simplifications was used by these prior investigators: (1) The concentration of the test solution was very low; (2) the hydroxyl ion concentration was very high and could be assumed constant; (3) the hydroxyl ion was assumed to be only a catalyst, and the variation of hydroxyl ion concentration was neglected ; (4) trimetaphosphate hydrolysis was assumed to proceed as a simple reaction-e.g., via either straight hydrolytic degradation: 272
l&EC PRODUCT RESEARCH A N D DEVELOPMENT
or via alkaline hydrolysis :
or P30g-3
+ 2 OH-
+
+
P ~ O I O - ~HzO
(24
and/or ( 5 ) the end product was not determined but assumed to be tripoly- or acid tripolyphosphate. Since in conventional commercial detergent processes the “solids” (nonvolatile a t 110’ C.) concentration in detergent slurries is very high, and the supply of the hydroxyl ion in such slurries is often limited, one could not determine from these prior data whether or not the conversion of sodium trimetaphosphate to sodium tripolyphosphate might be useful commercially in processes for the manufacture of detergents. T h e present study was aimed to elucidate the mechanism of the reaction of trimetaphosphate with base to yield tripolyphosphate, to measure the rate of this reaction a t various “solids” concentrations and various hydroxide concentrations, and to determine the end hydrolysis (reaction) product so that the potential role of sodium trimetaphosphate in processes for manufacturing built detergents could be determined. Experimental
The sodium trimetaphosphate used was made by heating a recrystallized monosodium orthophosphate monohydrate gradually to 610’ C. and holding it a t that temperature until
no trace of insoluble metaphosphate remained. The purity of the trimetaphosphate was 98.38% as determined by ion exchange chromatographic analysis (8). Carbon dioxidefree distilled water and 50% N a O H were used in subsequent tests. Other chemicals used were commercial reagent grade material, or of the highest quality available. Weighed samples of trimetaphosphate and sodium hydroxide, each with a portion of the water to be added in the final test solution, were equilibrated in sealed Erlenmeyer flasks a t the desired temperature in a Research Specialties Co. temperature-controlled water bath shaker, Model 21 56, modified by addition of a n electric heater, cooling coil, and Lux variable thermoregulator. Temperature was controlled to 3 ~ 0 . 2 'C. Time started when the trimetaphosphate solution was rapidly mixed with the sodium hydroxide solution. Approximately 2-ml. samples were drawn from the test mixture a t the desired times with a dropper and quenched immediately in a dilute, ice-cold, acetic acid-potassium acetate buffer solution a t p H 5.0. There was no visible precipitate in any test sample, except test 21, used in this part of studies. T h e quenched samples were kept under refrigeration until analyzed, never longer than a week. T h e ion exchange chromatographic procedure ( 8 ) was used to determine ortho-, pyro-, tripoly-, and trimetaphosphate in the test sample. Tetrametaphosphate could be determined by this method but was never found. Accuracy of this method was carefully determined as ~ k 0 . 2 7for~ any phosphate species. By follomhg the distribution of various phosphate species, the hydrolysis mechanism was established.
extrapolated rate constants is in good agreement with the observed values. I n test 21 (Table I) the test solution consisted of 6.GY0 N a 2 S 0 4 ,18.9% NabP3010, 2.1% Na3P309,and 2.4% NaOH. The N ~ ~ , P ~ O I O - N ~ ~ P ~ O solution ~ - - N ~was ~ Smade O ~ by dissolving a specially prepared Form I1 NabP3Ol0free of Na3P309 in a water solution containing the desired amount of N a 3 P 3 0 9 and N a ~ S 0 4 . I t was known in this laboratory that a highly supersaturated Na5P3Ol0 solution could be made in this manner. When N a O H solution was added to this solution Na6P3010. 6 H 2 0 started to crystallize. For this reason the solids concentration and ionic strength of this run are only approximate values. An analysis of the conversion rate revealed that the data could not be fitted by a conversion mechanism given by Equation 1, 2, or 2a. T h e data appeared to follow the mechanism expressed by a simplified consecutive reaction steps depicted by Equations 3 and 4. T h e actual reaction species would be more complicated than the simple trimetaphosphate anion shown in Equation 3 because of the hydration and metal cations associated with the trimetaphosphate anion.
Mechanism of Hydrolysis
T h e reaction depicted in Equation 3 is the rate-controlling step, from which the rate of hydrolysis of trimetaphosphate can be expressed as
Test results are summarized in Table I. T h e "solids" concentration was varied from 1 to 2070 by weight. T h e latter is close to the solubility of sodium trimetaphosphate a t the lower test temperature of 25' C. Although the kinetic rates of hydrolysis of trimetaphosphate were measured a t only two temperatures, it is believed that this is enough to define the temperature dependency of this reaction, because the activation energies and collision factors calculated from the rate constants a t these two temperatures were reasonably consistent and agreed with earlier values reported by Healy and Kilpatrick (5) and Indelli ( 6 ) , and the amount of trimetaphosphate converted in hot concentrated caustic solutions and boiling detergent slurries (described below) estimated from
+ OHHP3010-4 + OHP309-3
-t
+
HP~OIC-'
(Slow)
+
P 3 0 ~ ~ - 5 H20
- dA - - kAB = kA(Bo dt
- 2 Ao
(fast)
+ 2 A)
(3)
(4)
(5)
where A and B are molar concentrations of sodium trimetaphosphate and sodium hydroxide, respectively, and the subscript indicates the initial concentration. If Bo # 2 Ao, the reaction rate constant was evaluated from the following integrated equation. 1
BO - 2 A0 In
(g) =
kt
When Bo = 2 A0 the following equation was used. Table 1. Rate of Alkaline Hydrolysis of Trimetaphosphate Increase with Temperature, Solids Concentration, and Ratio of Sodium Hydroxide to Sodium Trimetaphosphate Reaction Total Rate ?.a' 0H / Na3P309 Solids Constant, N a 3 P30 Mole Tzmp., Concn., Concn., Ionic (Mole/L.)-l No, Ratio C. MolelL. W t . yo StrenEth (Mzn,)-l 1 1.0 25.0 0.1474 5.0 1.03 0,0046
2 3 4 5 6 7
8 9 10
1.0
2.0 1.0 2.0 1.0
2.0 0.5 1.0 2.0 4.0 0.5
25.0 25.0 25.0 25.0 25.0 50.0 50.0 50.0 50.0
50.0 50.0 50.0 1.0 50.0 2.0 50.0 4.0 50.0 1.0 50.0 2.0 50.0. 1.0 50.0 2.0 50.0 8.7 50.0 5% NanSOc added.
11 12 13" 14a 15O 16" 17 18 19 20 21 @
2.0
0.1321 0.3130 0.2805 0.6843 0.6160 0.0472 0.0261 0.1594 0.1474 0.1321 0.1117 0.1711 0.1661 0.1566 0.1410 0.3130 0.2805 0.6843 0.6160 0.0810
5 .O
10.0
10.0 20.0 20.0 1. o 1. o 5.0 5.0 5.0 5.0 10.0 10.0 10.0 10.0 10.0 10.0 20.0 20.0 30.0
1.06 2.18 2.23 4.80 4.83 0.33 0.21 1.01 1.03 1.06 1.12 2.43 2.44 2.45 2.33 2.18 2.23 4.80 4.83 5.95
0.0052 0.0064 0.0068 0.0102 0.0128 0.045 0.045 0.038 0.053 0.060 0.135 0.083 0.090 0.132 0.182 0.063 0.068 0.086 0.119 0.525
_ - _ --
A
2 kt
Ao
(7)
This mechanism implies that a t molar NaOH/Na3P309 values less than 2, there is a practical limit to the fraction of trimetaphosphate that can be converted. T h e present results showed this to be the case and Equations 6 and 7 were closely followed all the way to over 95% of the N a O H consumed. This also shows that, for a given experiment, the reaction constant, k , is indeed constant. When the hydroxyl ion concentration is high relative to the phosphate concentration, the reaction may be assumed to follow a first order, as observed by Healy and Kilpatrick (5). When the mole ratio of hydroxide to trimetaphosphate is only 3 to 4, the reaction constants calculated by a first-order relationship will be in error according to the present mechanism. For this reason, the rate constants reported by Brovkina (3) are believed incorrect. Temperature Dependence
T h e reaction rate constants of the various concentrations and NaOH/Na3P309 ratios appear to follow the Arrhenius law. As shown in Table 11, the activation energy and the collision factor, A , drop with a n increase in concentration. This comVOL. 5
NO. 3
SEPTEMBER 1966
273
Table II.
Activation Energies and Frequency Factors
Na OH/ NaaPaO 9 Mole Ratio
AE, Kcal./Mole
LOP10 A L. /( Mole) (Min.)
5
1 .o 2.0
17.5 17.5
10.6 10.6
10
1.o 2.0
16.4 16.5
9.9 9.9
20
1. o 2.0
15.3 16.0
9.3 9.8
Solids Concn.,
%
wt.
pares favorably with Indelli's results (6) which showed that, on increase in concentration from 0.01 to 0.04 mole of N a 3 P 3 0 9 per liter with equal molar concentration of NaOH, the activation energy drops from 17.3 to 16.2 kcal. per mole and loglo A drops from 10.9 to 10.5. O n the other hand, Healy and Kilpatrick (5) found that a t a P309-3 concentration of 10-4 to 10-8 mole per liter with 0.05 to 0.18 mole per liter NaOH, the activation energy and loglo A vary from 15.5 to 17.5 kcal. per mole and 8.4 to 10.0 liters/(mole) (min.), respectively. Concentration Dependence
Although the reaction rate constant increases with solids concentration a t all times, the increase does not follow a simple scheme, because too many factors tend to influence each other. However, the following conclusions could be drawn from the present test results. For a given NaOH/Na3P309 ratio, the reaction rate increases with a n increase of solids concentration or ionic strength. Similar effect of solid concentration was also noted for degradation of sodium tripolyphosphate in concentrated solutions (10). T h e rate constant increases with NaOH/Na3P3Og mole ratio. This trend appears to continue even a t ratios as high as 250 to 10,000, as noted by Healy and Kilpatric!c (5). T h e rate increases with addition of sodium sulfate, even though the total solids concentration is held constant. The significant increase in rate constant cannot be explained by catalytic effect of sodium ion (5, 73, 74). At very high solids concentrations and high NaOH/Na3P309 ratio and with the presence of sodium sulfate as shown in test 21, the reaction rate constant was very high. This rate appears to be consistent with other results when a correlation is made between rate constant and logarithmic values of the square root of ionic strength. About 98% of N a 3 P 3 0 9was converted to NasP3010 in 30 minutes under these conditions. Hydrolyzed Product from Trimetaphosphate
I n all tests a t 25' and 50' C. after 1 hour, the ion exchange chromatographic analyses showed that the product of alkaline hydrolysis of Na3P309 is NasP3010. T h e amount of orthoand pyrophosphate fractions was substantially unchanged. This indicates that the primary reaction in hydrolysis of sodium trimetaphosphate is to open the trimeta-ring structure to a tripolyphosphate chain. T h e mechanism and kinetic data presented above show that the production of acid tripolyphosphate from trimetaphosphate by alkaline hydrolysis will not be feasible, because the acid tripolyphosphate, as a n initial intermediate in the hydrolysis of trimetaphosphate, rapidly combines with hydroxyl ion to form tripolyphosphate. When the concentration of hydroxide ion is so low that acid tripolyphosphate will not be neutralized, the hydrolysis rate will be too low to be practical. However, there is a remote chance that rapid drying of a con274
I & E C PRODUCT RESEARCH A N D DEVELOPMENT
centrated stoichiometric mixture of sodium hydroxide and sodium trimetaphosphate a t the acid tripolyphosphate composition will yield a product of essential acid tripolyphosphate. The high temperature and high solids concentration may change the hydrolysis mechanism. Should this assumption be wrong, the results will verify the validity of the proposed mechanism under the unusual conditions. Freshly made room temperature solutions of sodium hydroxide and sodium trimetaphosphate solution a t various NaOH/Na3P3Og mole ratios and solids concentrations were added dropwise onto a drum dryer heated by 60-p.s.i.g. steam and rotated a t 4.8 r.p.m. T h e dried material was collected and analyzed by the ion exchange chromatographic procedure. The results given in Table I11 show that the trimetaphosphate conversion stops practically a t the point predicted by Equations 3 and 4-that is, it is impossible to make sodium acid tripolyphosphate by direct hydrolysis of sodium trimetaphosphate with sodium hydroxide. The ortho- and pyrophosphates present in the dried samples are a result of decomposition of the sodium tripolyphosphate hexahydrate (9, 7 7). Although the test compositions for test G 6 were different from those of test G 5 , the degradation of tripolyphosphate converted from trimetaphosphate in drying is notably less than that from the tripolyphosphate solution a t the start. Under these test conditions, conversion of trimetaphosphate to tripolyphosphate is very rapid and essentially complete. Comparing the results of tests G 3, G 4, and G 5, it seems that the presence of additional N a O H (more than the stoichiometrical amount needed to react with trimetaphosphate) will enhance degradation of tripolyphosphate. Degradation Action of Concentrated NaOH
A series of studies, in which N a 3 P 3 0 9powder was mixed with a large excess of N a O H of varying concentrations in distilled water, showed that the sodium tripolyphosphate produced from the trimetaphosphate will degrade in very highly concentrated N a O H solution a t a very fast rate according to the reaction
+ 2 NaOH
NajP3OI0
-P
Na3P04
+ NarPs07 + HzO
(8)
The test results are depicted in Figures 1 and 2. The degradation rate, as expected, increased with temperature. T h e reaction rate constants for converting trimetaphosphate to tripolyphosphate and for degradation of tripolyphosphate can be estimated from the test results by solving a series of simultaneous differential equations. These calculated constants of the conversion rate of trimetaphosphate in concentrated N a O H solutions are in good agreement with values obtained from extrapolation of the experimental data given in Table I to a comparable concentrated salt solution.
Table 111.
Analyses of Drum-Dried Solution of Sodium Trimetaphosphate and Sodium Hydroxide Test No. G7 G 2 G 3 G4 G5 G6"
Solids concn., wt.
%
10.0
NaOH/NaaPa09 0 . 5
10.0 1.0
10.0 2.0
10.0 4.0
20.0 2.0
30.0 8.7
Ion Exchange Chromatographic Analyses of Dried Material, P 7 0 Basis 1.50 9.05 5.72 2.50 19.00 4.0 Ortho 8.11 44.05 21.50 22.98 14.03 52.86 Pyro 4.16 23.22 80.18 27.67 88.18 46.57 Tripoly 2.18 0.32 0.45 3.28 70.34 48.08 Trimeta Composition same as test 27 in Table I.
VI
Conditions: 20% NoOH 50. C. N~OH/(NOPO,),=
b
c
n ln
70
8.0
Conditions:
0
E +
70. C. 20% NoOH N~OH/(NOPO,),
0) c
f
401
n
P
= 8.0
I
0)
30
Ortho or Pyro
10 1
I
Trlrnita
0240. 300 6
08-0
.
.360 0 420 0 '
4
._ 40
0
Ortho or Pyro
-_
.. 120
80
_.
!
160
+
200
,
L
280
240
Time, Min. Conditions:
70. C. 35% NOOH
= 8.0
NaoH/(NoPO,), 'r
\
'
Trlpoly
'\
4
c
0 c
2
2
Time, Min.
3o I
Trimela
I)
IooL 90
/:.. h I
0
.-.. ?--$ 0
60
120
Ortho
-+-.-
----_ _ _ _ _
Trimeta
+.
180
240
300
360
rl
Tripoly7
420
480
540
600
Time, Min.
40
I
I
I
I
.
120
80
l
l
160
l
,
200
l
240
l
l
,280
Time, Min
'""I
Conditions: 70* C.
50% NeOH
90
ln
2
0 s u) Q
c 0 (L
Figure 1. Effects of NaOH concentration and temperature on final hydrolysis products from (NaP03)~at 50" C. NaOH/(NaP03)8 = 8.0 Upper. 20% NaOH Center. 35% NaOH lower.
4-
0 c
2
2
50% NaOH
Conversion of Trimetaphosphate by N a ~ C 0 3
Sodium carbonate can be used to convert trimetaphosphate to tripolyphosphate, but at a conversion rate significantly lower than in a comparable (molar concentration of reactants, types of materials, temperature, etc.) sodium hydroxide solution. For example, a t 70' C. and in a 20% solids solution, about 2 minutes is required to convert about 50% of the Na3P309in the presence of a stoichiometric quantity of N a O H ; about 200 minutes is required to convert 50% of the NasP3Og when N a 2 C 0 3 is used in place of N a O H in this test. I t is probable that there is less than one sodium available from N a ~ C 0 3and the conversion probably stops before the carbonate changes to bicarbonate. This assumption is based on the fact that the conversion rate of N a 3 P 3 0 9to NabP3010 becomes very slow as the p H drops to about 9 to 10. Conversion of Trimetaphosphate by Sodium Silicate
Because sodium silicates with high SiO*/NazO mole ratios are often present in a detergent slurry, tests were made to
Time, Min. Figure 2. Effects of NaOH concentration and temperature on final hydrolysis products from (NaPO& at 70" C. NaOH/(NaP03)3 = 8.0 20% NaOH 35% NaOH 50% NaOH
Upper. Center. lower.
determine the effect of silicates on the conversion rate of trimetaphosphate. The results indicate that in the presence of sodium silicate with a SiOz/NazO weight 70ratio greater than 2.0, the conversion rate of Na3P309 decreases slightly. For liquid silicates with a SiO*/NaZO weight yo ratio between 2.0 and 3.2, the change of the conversion rate due to the presence of excess sodium silicate is relatively small in comparison with changes caused by temperature, concentration, or NaOH/ N a 3 P 3 0 9ratio. T h e conversion rate of Na3P309 is significantly higher in the presence of silicates having SiOz/NaOH ratios VOL. 5
NO. 3
SEPTEMBER 1966
275
significantly lower than 2.0. Such “lower ratio” silicatesfor example, sodium metasilicate-can provide necessary hydroxyl ion to hydrolyze Na3P30s.
source of sodium tripolyphosphate in practical detergent manufacturing processes, and even to eliminate the spray dryer now widely used in manufacturing light density detergents.
Discussion
Measurements on the hydrolysis rates of sodium trimetaphosphate to tripolyphosphate in detergent slurries containing less than 60Y0 solids show that the rate constants are essentially the same as the values estimated, assuming that the conversion takes place in the aqueous phase. This indicates that for most detergent slurries the rate-controlling step is the chemical reaction. O n the basis of this work, it appears that a t 100’ C., the conversion of trimetaphosphate to tripolyphosphate is 97y0 completed in about 5 minutes. O n the basis of the kinetic rate data (of relatively dilute solutions) reported heretofore, this high conversion rate was not expected. The alkaline hydrolysis reaction of trimetaphosphate to tripolyphosphate hexahydrate is highly exothermic. T h e enthalpy change was measured to be -21.46 kcal. per mole. For a detergent slurry containing about 60 to 70% by weight of solids and a t a temperature of about 60’ to 100’ C., the amount of water evaporated from the slurry due to the heat of reaction of a large amount of trimetaphosphate with 5oY0 NaOH, coupled with a n additional large amount of water immobilized by the formation of Na6P3010.6 H20 (77) makes it possible to convert a pumpable detergent slurry directly into a solid built detergent having a relatively low density. Thus, contrary to what one might expect as the result of data available in the sodium trimetaphosphate chemical literature, sodium trimetaphosphate can be advantageously used as a
Acknowledgment
The author expresses his appreciation to C. F. Callis for supporting this investigation and to J. S. Metcalf for helpful discussions. literature Cited
(1) Bell, R. N., Znd. Eng. Chem. 39, 136 (1947). (2) Bjerrum, J., Schwarzenbach, G., Sillen, L. G., “Stability of Metal Complexes,” Part 11, p. 63, Chemical Society, London, 1958. (3) Brovkina, I. A., Zh. Obshch. Khim. 22, 1917 (1952). (4) Hatch, G. B., U. S. Patent 2,365,190 (Dec. 19, 1944). (5) Healy, R. M., Kilpatrick, M. L., J . Am. Chem. SOC.77, 5258 (1955); 79, 6575 (1957). (6) Indelli, A., Ann. Chim. 46, 367 (1956). (7) Kiehl, S. J., Coats, M., J . Am. Chem. SOC.49, 2190 (1927). (8) Kolloff, R. H., A . S. T. M . Bull. 237,74 (1959). (9) Quimby, 0.T., J . Phys. Chem. 58, 603 (1954). (10) Shen, C. Y., Dyroff, D. R., IND.ENG. CHEM.PROD.RES. DEVELOP. 5,97 (1966). (11) Shen, C. Y.,Metcalf, J. S., O’Grady, E. V., Znd. Ens. Chcm. 51. 717 (1959). (12) ’Van Waze;, J. R., “Phosphorus and Its Compounds,” Vol. I, Interscience, New York, 1958. (13) Van Wazer, J. R., Campanella, D. A., J . Am. Chem. SOC.72, 655 (1950). (14) Wieker, V. W., Thilo, E., 2.Anorg. Allgem. Chem. 306, 48 (1960).
RECEIVED for review February 16, 1966 ACCEPTEDJune 20, 1966
STARCH-D ERIVED GLYCOL GLYCOSIDE POLYETHERS FOR URETHANE FOAMS. PROCESS SCALE-UP, PERFORMANCE IN FOAMS, AND COST ESTIMATES R. H. L E I T H E I S E R , C. N . I M P O L A , A N D R . J . Archer Daniels Midland Co., Minneapolis, Minn. F. H. O T E Y Northern Regional Research Laboratory, Peoria, Ill.
R E I D
In a pilot-plant study of the preparation of polyethers from glycol glycosides obtained directly from starch, scale-up from a laboratory procedure was readily achieved to 1000 pounds of polyether per batch. Extensive evaluation of the polyethers for use in rigid urethane foams was made by appropriate formulation with PAPI or Nacconate 4040 isocyanates, with and without flame retardants, and with machine foaming. “Plant gate cost” of the polyethers was estimated to be around 15 cents per pound, based on current raw material and plant operating costs. Fixed capital investment was estimated at $375,000 for construction of a unit designed to produce 10,000,000 pounds of polyether per year. The low production cost of the new polyethers is expected to make them competitive with polyethers currently in use.
urethane foams are made by cross-linking~. polyethers R ’ T t h various isocyanates in the presence of a catalyst, surfactant, blowing agent, and, if desired, fire retardant agents. Polyethers now used by the industry are prepared by reaction of propylene oxide with such poly01 initiators as sorbitol, methyl glucoside, sucrose, and pentaerythritol until a liquid with the desired viscosity and hydroxyl number is ob276
I&EC PRODUCT RESEARCH A N D DEVELOPMENT
tained. (Manufacturers of propylene oxide should be consulted for safe handling procedures) T h e feasibility of producing polyethers from corn starch, by transglycosylation with ethylene glycol or glycerol followed by propoxylation, was demonstrated on a laboratory level (2-4). These studies established preferential conditions for preparing the intermediate glycosides: a 4 to 1 molar ratio of ethylene
