EXOTHERMIC
’
A,’ DIFFERENTIAL THERMAL
Several different forms of alumina were studied in an effort to discover which hydroxyl groups were reacting to produce the three endotherms. The DTA of fresh alumina trihydrate (Figure 4A) was found to be similar to that of the fresh catalyst. Since alumina trihydrate is used as one of the raw materials for the manufacture of silica-alumina catalyst, its presence is not surprising. The three endotherms in Figure 4A are caused by the following three reactions ( 2 ):
ANALYSIS
V I
I
0
100
I
I
t
1
200
300
400
SO0
a-Alz03.3HzO + y-Alz03.HzO
y-Al203.HzO
8. THERMOORAVIMETRIC ANALYSIS
SAMPLE WEIGHT a 300 MG. ABS. PRESSURE= 25 MM. Hg, HEATING RATE 6’CIMIN.
-
Y
v)
40
v)
g
70 BO
eo too
100
200
XI0
400
500
600
+ 3 HzO y-Al-208 + HzO
a-Alz03*3HzO+ x-Alz03
TEMPERATURE (‘C)
--*
+ 2 HzO
(1)
(2)
(3 1
The endothermic peaks in fresh silica-alumina catalyst closely match the peaks for the dehydration of pure alumina trihydrate. This fact, together with knowledge that the evolved water is associated with aluminum atoms and not silicon atoms, suggests that the three endothermic peaks in silica alumina represent the presence of alumina tri hydrate-Le., alumina which has not reacted with a silanol group to form an A1-0-Si type bond. The total quantity of unreacted trihydrate in the sample studied was estimated to be 10% of the total aluminum based on the TGA data. Since the endothermic evolution of the water is irreversible, the trihydrate cannot be detected in samples which have been heated above 300’ C.
700
TEMPERATURE (‘C)
Figure 4. Differential thermal and thermogravimetric analyses of alumina trihydrate
acid-treated catalyst is shown in Figure 3B. The endothermic peak has disappeared, and it can be concluded that the water which produced the peak must have been associated with the aluminum atoms in the catalyst rather than the silicon atoms. Once the catalyst has been heated above 300’ C., various attempts at reversing the reaction by soaking in water or by vapor-phase rehydration proved to be unsuccessful. Figure 3C is the DTA of a calcined and rewetted catalyst, demonstrating the irreversibility of the reaction (TGA shown in Figure 2 B). Thus it appeared reasonable to conclude that the water might be a decomposition product of an alumina.
Conclusions and Applications
By using DTA and TGA it appears possible to detect the presence and the amount of unreacted aluminum in silicaalumina cracking catalyst. The simple test developed in this study could prove a useful means for monitoring the catalystmanufacturing process. literature Cited
(1) Basila, M. R., J.Phys. Chem. 66, 2223 (1962). (2) Brindley, G. W., Nakahira, M., Z . Krist. 112,136 (1959). ( 3 Brosset, C., Acta Chem. Scand. 8, 1917 (1954). (41 Eitel, W ., “Silicate Science,” Vol. I, p. 324, Academic Press, New York, 1964. ( 5 ) Locke, C. E., M.S. thesis, University ofTexas, 1960. (6) . , Shearon, W. H., Fullem, W. R., Znd. En?. - Chem. 51, 720 (1959). (7) Tamele, M. W., Discussions Faraday SOC.8,270 (1950).
RECEIVED for review September 7, 1965 ACCEPTED February 18, 1966
CHLOROALKYL PHOSPHINIC ACIDS Preparation and Reaction with Cotton LEON H. CHANCE, ETHEL K. LEONARD, AND GEORGE L. DRAKE, JR. Southern Regional Research Laboratory, N e w Orleans, La.
program of cotton research, to impart useful properties to cotton by chemical treatment, has been carried out by the U. S. Department of Agriculture. Reactions related to those reported here were investigated in recent years a t this laboratory. I n 1956, Chance, Warren, and Gu‘thrie disclosed a process for reaction of 2-chloroethylphos-
A
252
BROAD
l&EC PRODUCT RESEARCH A N D DEVELOPMENT
phoric acid with cotton fabric in the presence of excess alkali to produce a phosphatoethyl ether of cotton with cationexchange properties ( 5 ) . In a similar way Drake, Reeves, and Guthrie made chloromethylphosphonic acid react with cotton fabric to produce the phosphonomethyl ether of cotton with cation-exchange properties and improved flame resistance
~~~~
~~
Two new compounds, bis( 1 -hydroxy-2-chloroisopropyl)phosphinicand bis(1-hydroxy-2,2 ’-dichloroisopropy1)phosphinic acids, were prepared by the reaction of hypophosphorous acid with chloro-2-propanone and 1,3-dichloro-2-propanone, respectively. Bis(chloromethy1)phosphinic acid was also prepared b y the reaction of bis(hydroxymethy1)phosphinic acid with thionyl chloride, a method not previously reported. All three acids were applied to cotton from aqueous solutions containing an excess of sodium hydroxide or sodium carbonate as a catalyst, and cured at elevated temperatures. Fabric samples treated with all three compounds were insoluble in cupriethylenediamine dihydroxide and had improved wet wrinkle recovery, indications that the cellulose was crosslinked. Analysis of the fabric showed the presence of one exchangeable hydrogen ion for each phosphorus atom, evidence of the presence of phosphinic acid groups in the fabric. Apparently, the cellulose hydroxyl groups react with the chlorine atoms of the phosphinic acids in the presence of a base to crosslink the cellulose by ether linkages. There was no significant improvement in dry wrinkle recovery over that of untreated cotton. Moisture regain values were considerably higher than those of untreated cotton. Fabric strength losses were not excessive when considering the degree of crosslinking.
when the cation was NH4+ (6). These reactions proceeded by the reaction of the chlorine atoms with the cellulose hydroxyl groups in the presence of a base. The organophosphorus compounds described above were monofunctional in their reaction with cellulose, and therefore were not capable of crosslinking. Cotton fabrics treated with these compounds had a crisp starched appearance and were slick to the touch when wet. These properties were due to the solubilizing effect of the phosphoric acid and phosphonic acid groups on the fabric. At high degrees of substitution the cotton dissolved in watw and lost its fibrous structure. The previous research on phosphatoethyl and phosphonomethyl cotton suggested that organophosphorus acids containing two or more cellulose reactive chlorine atoms would crosslink the cellulose and thereby improve the wrinkle recovery of cotton. Further, if one chose a phosphinic acid instead of a phosphoric or phosphonic acid, the cation-exchange values would be lower, and thereby might decrease or eliminate the stiff hand and slick feeling. The compounds chosen for this study were bis(chloromethy1)phosphinic acid (BCPA), bis (1-hydroxy-2-chloroisopropyl)phosphinic acid (HCPA), and bis(l-hydroxy-2,2’-dichloroisopropyl)phosphinic acid (HDPA). The latter two compounds have chlorohydrin structures and should react with cellulose in a manner similar to that proposed by Gagarine (7), in which dichloropropanol crosslinks cellulose in the presence of a base, presumably through the mechanism of the formation of epoxy groups. In 1961, Moedritzer reported the preparation of bis(ch1oromethy1)phosphinic acid (BCPA) by a rather lengthy procedure ( 7 7). He made chloromethylphosphonothionic dichloride react with triphenyl phosphite and obtained chloromethyl dichlorophosphine by desulfurization. He then made the latter react with paraformaldehyde, and obtained a mixture of bis(chloromethy1)phosphinic dichloride and the anhydride of bis(chloromethy1)phosphinic acid. The free phosphinic acid (BCPA) was obtained by hydrolysis of the acid chloride or the anhydride. In the present work BCPA was prepared by a simple procedure shown by Equations 1 and 2. (HOCH2)aP(O) (OH)
+ 3soc12
+
(ClCH2)zP(O)Cl (ClCH2)2P(O)Cl
+ H20
+ 3 S o z + 3HC1
(1)
+
(ClCH2)2P(O)OH
+ HCl
(2)
In 1901, Marie (70) described the preparation of bis(1-hydroxyisopropy1)phosphinic acid by the reaction of acetone and
hypophosphorous acid. Very low yields are obtained even after refluxing for several days. The reaction of chloro-2propanone and 1,3-dichlor0-2-propanone described below proceeded more readily with higher yields. This was attributed to the activating influence of the chlorine atoms. In general, reactions of this type are considered to be a nucleophilic attack by the phosphorus compounds on the carbonyl groups, which is promoted by the acid-catalyzed formation of an electron-deficient center, such as a carbonium ion (8). HCPA was prepared by the reaction of hypophosphorous acid and chloro-2-propanone (Equation 3).
O H HO-P
/I / \
0
II + 2ClCH2-C--CHa
+
H
HDPA was prepared by the reaction of hypophosphorous acid and 1,3-dichloro-2-propanone(Equation 4).
+ 2ClCH2-C-CHzCl+
HO-P
\ H
0
Materials and Methods
Preparation of Bis(chloromethy1)phosphinic Acid. Bis(hydroxymethy1)phosphinic acid (126.0 grams, 1.O mole) was added gradually with stirring to a flask containing thionyl chloride (416.5 grams, 3.5 moles). The reaction flask became cold, indicating an endothermic reaction. The reaction was allowed to stand overnight, and the excess thionyl chloride was removed by distillation. The crude yield of bis(chloromethy1)phosphinic chloride (BCPC) was 94y0,. I t was converted to BCPA as follows: Crude BCPC (170.0 grams, 0.94 mole) was dissolved in 265 ml. of benzene and added dropwise with stirring to a flask containing 395 ml. of benzene and water (20.0 grams, 1.1 moles). Stirring was continued for 1 hour at room temperature, and finally the mixture was refluxed for 1 VOL 5
NO. 3 S E P T E M B E R 1 . 9 6 6 253
hour. The flask was cooled in ice water, and the white crystals which separated were filtered. A 100% yield of crude BCPA (m.p. 75-79' C.) was obtained. The crude BCPA was stirred with a mixture of 240 ml. of benzene containing 60 ml. of acetone, cooled in ice water, and filtered. The recovery was 73y0 of white crystals (m.p. 77-80' C.). A pure sample (m.p. 80.5-81.5' C.) was obtained by recrystallizing from benzene-acetone. Melting point reported in literature, 78' C. (8). Analysis. Calculated for C ~ H ~ O ~ C I C, Z P14.74; : H, 3.09; Cl, 43.52; P, 19.01; equivalent weight, 162.59. Found: C, 14.81; H , 3.11; Cl, 43.56; P, 19.10; equivalent weight, 160.30. Preparation of Bis(1-hydroxy-2-chloroisopropyl)phosphinic Acid (HCPA). Crystalline hypophosphorous acid (33.0 grams, 0.5 mole) was dissolved in chloro-2-propanone (185.0 grams, 2.0 moles). The solution was heated on a water bath for 1s1/z hours at 80' C. During the heating period the mixture turned black and crystallized to a solid mass. The mass was slurried vigorously with 300 ml. of benzene to dissolve the black material, and the crystals were filtered. Additional crystals were recovered by concentration of the benzene filtrate. The crystals were slurried again with 150 ml. of benzene containing 5 ml. of ethanol. The yield of crude HCPA [m.p. 149-50' C. (corr.)] was 72.3 grams (57.6%) based on hypophosphorous acid. Whiter crystals [m.p. 150-51' C. (corr.)] were obtained by slurrying again with hot benzene-ethanol, and washing the crystals on the filter with acetonitrile. Analytically pure crystals [m.p. 153.5-54.5' C. (corr.) J were obtained by recrystallization from benzene-ethanol. Analysis. Calculated for C ~ H I ~ O ~ CC,~ ~28.72; P: H, 5.19; C1, 28.25; P, 12.34; equivalent weight, 250.93. Found: C, 29.03; H, 5.37; CI? 27.47; P, 11.57; equivalent weight, 247.91. Preparation of Bis(l-hydroxy-2,2'-dichloroisopropyl)phosphinic Acid (HDPA). 1.3-Dichloro-2-propanone(63.5 grams, 0.5 mole) and crystalline hypophosphorous acid (13.2 grams, 0.2 mole) were mixed and melted at 50" C. to make a homogeneous solution. Heating at 50' C. was continued for 15l/2 hours. During this time the melt solidified to a white crystalline mass. The crystals were stirred successively nith two 50-ml. portions of hot benzene to remove unreacted materials. The crystals weighed 56.7 grams. Additional crystals (1.6 grams) were recovered from the benzene. The total crude yield was 58.3 grams (9170) [m.p. 137-39' C. (corr,)]. Analytically pure HDPA [m.p. 141-42' C. (corr.)] was obtained by recrystallization from a mixture of benzene and ethanol. Analysis. Calculated for C~H1104C14P: C, 22.52; H , 3.47: C1, 44.32; P, 9.68. Found: C, 22.91; H, 3.64; C1, 43.54; P, 8.90. The eauivalent weieht could not be determined by direct titration k i t h 0.1N N i O H because the chlorine atoms were labile enough to hydrolyze during the titration. Therefore the HDPA was heated in an excess of standard 0.lA' NaOH for 2l/? hours at 65' to 70' C. to hydrolyze all four chlorine atoms. The solution was then back-titrated Lvith standard 0.1N HCl. The calculated equivalent weight by this method is one fifth of the molecular weight, or 63.97. The equivalent weight found by this method was 62.15. Fabric Treatment. The fabric used in the experiments was a desized, scoured, bleached, and mercerized 89 X 78 cotton print cloth. Treating solutions were prepared by dissolving the phosphinic acids in NaOH or NaZC03 solutions of concentration such that the desired concentration of base remained after neutralization of the acid. The solutions were used when freshly prepared as well as after aging for 2, 4, and 24 hours a t room temperature. The solutions were applied to the fabric by conventional padding procedures to give a wet add-on of about 85 to 105%, depending on the concentration of NaOH and phosphinic acid. The fabric was dried for 5 minutes at 85'C., cured at the appropriate temperature, rinsed in hot water, and airdried. Fabric Test Methods. All textile tests on treated fabrics were performed on samples in the sodium salt form. Textile tests were performed under controlled conditions of 70' F. and 65% RH, conforming to ASTM standard methods 254
I&EC PRODUCT RESEARCH A N D DEVELOPMENT
for the following tests: tearing strength by the Elmendorf method (7), wrinkle recovery angles by the Monsanto method ( 2 ) ,breaking strength by the 1-inch strip method ( 3 ) ,and moisture regain ( 4 ) . Phosphorus content was determined by the colorimetric reduced molybdate method after digestion with sulfuric acid and hydrogen peroxide (72). Crosslinking of the cellulose was indicated by placing the cotton fibers in cupriethylenediamine dihydroxide solution, and observing their solubility and swelling characteristics visually with a microscope. Cation-exchange capacities were determined by the method of Hoffpauir and Guthrie ( 9 ) , omitting the addition of 1 M NaCl and using only 20-minute equilibration time. Experimental and Discussion
Effect of NaOH Concentration on Wet Wrinkle Recovery a n d Phosphorus Content. Experiments were carried out in which a series of cotton fabric samples was treated at different concentrations of NaOH while the concentration of the particular phosphinic acid was held constant. The concentrations of BCPA, HCPA, and HDPA were 10, 15, and 15%, corresponding to molar concentrations of 0.61, 0.60, and 0.47 moles per kg., respectively. These concentrations were based on the phosphinic acids as such, even though they were present in the solutions as the sodium salts. All of the fabric samples were wetted with freshly prepared solutions, dried for 5 minutes at 85' C., and cured for 5 minutes at 140' C. The relationship between sodium hydroxide concentration, phosphorus content, and wet wrinkle recovery angles (WRA) is shown in Figures 1 and 2. There was an optimum NaOH concentration for obtaining maximum reaction as indicated by phosphorus content for all three compounds (Figure 1). The optimum concentrations of NaOH for BCPA, HCPA, and HDPA were 7, 10, and 157,, respectively. At higher N a O H
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15 CONCENTRATION,% 10
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NaOH Figure 1 . Effect of NaOH concentration on phosphorus content of cotton fabric treated with BCPA, HCPA, and HDPA
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