Xorm
July, 1961
1273
st,uffs by precipitated hydrous oxides have been carried out in these laboratories. Tewari, Dey and Ghoshg from a considerat'ion of adsorption of dyestuffs by hydrous oxides attempted to elucidate the mechanism of' aging of metal hydroxides. This paper records our observations on the association of the acid dye, congo red, with samples of hydrous thorium oxide obtained by different methods.
this case the acidic and the basic characters of the hydrous oxide more nearly neutralize each other in sample C than in others and its adsorptive power is least both for acidic and basic dyes. It will be of interest to note that Dey and Ghosh5studied the amphoteric behavior of hydrous stannic oxide and found that a t the isoelectric point, the hydrous oxide showed the minimum adsorption for both acidic and basic dyes. I n this case sample C appears to approach an isoelectric sample more Experimental Materials.--Aqueous solutions of thorium chloride nearly than others, and has the least capacity to (BDH LR), sodium hydroside (BDH AnalaR) and congo red adsorb congo red which is further confirmed by were prepared and standardized. adsorption of basic dyes also.10 The other samples, Apparatus.-The absorbance of the dye was studied with a Unicam SP 500 spectrophotometer operated on 220 volts/50 A, B and D show the adsorption in the same order cycles single phase, a x . mains with the help of a Doran depending on their diminishing basic character and stabilized mains unit. The measuring cells were glass of 10 the observations are explainable on the amphotermm. thickness, supplied n-ith the instrument. The experi- ism of the hydrous oxide. ments were conducted in an air-conditioned room maintainIt is also to be mentioned that congo red is ading 20'. sorbed considerably by all the samples of hydrous Colorimetric meaiiurements were done by using KlettSummerson's photoelectric colorimeter operated on the same thorium oxide as has been seen from the high values mains using color filter no. 50 (transmission 470 to 530 mp) of x / m in the experiments. The solutions a t chosen after ascertaining the region of maximum absorption equilibrium become very faint in color and the of the dye. pH measurements were done with an L. and N. pH indi- adsorbents assume an orange color due to the ascator operated on the same mains with a glass-calomel elec- sociation of the dye. trode system. Acknowledgment.-The authors express their Color of the Dye at Different pH.-It was found that the absorbance of the dye a t 500 mp remains constant a t pH 5.8 gratitude to the Council of Scientific and Indnstrial Research, India, for supporting the work and to 8.9 and all deterniinations were done at p H 6.8. Validity of Beer's Law.-Beer's law was valid in the range for granting an assistantship to R.P. 4 to 12 p.p.m. of the dye and hence colorimetric estimations were done in ,this range of concentration. Preparation of Samples of the Hydrous Oxide .-Samples A, B, C and D of the hydrous oxide were obtained by adding calculat.ed amounts of a standard solution of sodium hydroside to 500 ml. of 0.251M thorium chloride solution a t 25" A precipitated with 10% deficient sodium hydroxide B precipitated with equivalent sodium hydroxide C precipitated with 5% excess sodium hydroside I> precipitated with 10yo excess sodium hydroxide The samples were thoroughly washed Rrith water till the washings were free from thorium (where present), hydroxyl and chlorine ions. The precipitates were suspended in water, vigorously shaken in a Microid Flask Shaker and the final volumes were raised by dilution with water to 10 g. of Tho2 per liter. Adsorption Experiments.-To 1 ml. of the suspension (0.01 g.), varying arnount,s of the dye were added and the volumes were raised to 100 ml. The systems were allowed to equilibrate for 24 hours. In the supernatant liquid, the concentration of congo red was estimated by the colorimeter.
Discussion The results show that the adsorptive capacit'ies of the samples decrease mith rise in temperature. Among the four sa,mples A, B, C and D, the basic character of' the hydrous oxide diminishes in the order above mentioned, on account of the increasing amounts of a1.kali used for their precipitation. Hence, it is expected that an acid should be adsorbed most by sample A and least by sample D. The order of adsorption as noted in this paper is A > B > D > C, showing thereby that C has the least adsorpi.ivecapacity. It is well known that amphoteric bodies depend on environmental conditions to display their acidic or basic characters. It may be concluded that in (6) 9. N. Teasri, Kolloid-Z., 128, 19 (1952). (7) R. B. Hajela and S. Ghosh, Proc. Natl. Acad. Sci. Indin, 2 8 8 , 59, 118, 130 (1959). (8) S. N. Teauri and Si. Ghosh, ibid., ala, 29, 41 (1952). (9) S.N. Tewari. A. K. Dey and S. Ghosh, 2.anorp. Chsm.. 171, 150 (1953).
(IO) R. Prasad and A. K. Dey (unpublished work).
ELECTRIC MOMENTS OF SOME ADDITION COMPOUNDS OF ZINC CHLORIDE WITH ORGANIC BASES BY M. JUDITHSCHMELZ,~ M. ANNGERTRUDEHILL^ AND COLUMBA CURRAN
Department of Chetntstry, Universztv of Notre Dame, Notre Dame, Indznna Recezved December 69. 1960
The determination of electric dipole moments of coordination compounds of zinc chloride with organic bases has been hindered by the low solubility of most of these complexes in non-polar solvents. Dioxane mas observed to have adequate solvent properties for the complexes of zinc chloride with pyridines and the picolines for dielectric constant measurements, and benzene is a suitable solvent for dichlorobis-(triethy1phosphine)-zinc. The moments of these addition compounds along with that of boron trichloride-pyridine have been determined for comparison with values previously obtained for other metal complexes. Dielectric constant measurements also were made on dioxane solutions of the complexes of zinc chloride with aniline and the toluidines but these are not reported, as spectroscopic measurements reveal that these complexes are partially dissociated in this solvent. Experimental The pyridine and picoline complexes were prepared by the addition of freshly distilled ligand to aqueous solutions of zinc chloride in mole ratios of 2: 1. The addition compounds were recrystallized from ethanol and dried over sulfuric acid. ( 1 ) Sister Mary Judith Rchmels, R.S.M.. and Sister M. Ann Gertrude Hill, O.S.U. Supported under AEC Contract AT(ll-1)-38, Radiation Laboratory of the University of Notre Dame.
1274
T'ol. 65
NOTES
POLARIZATIONS A S D
Compound
--70
Calcd.
ZnClp(C6HsN) 24.08 ZnClp(CK-CH~C'SHJ)~ 21.99 ZnCls(pCH3CjHJ)z 21.99 ZnCl&CH&$H4N) ZnCl2( Y - C H ~ C ~ H ~ N ) ~ 21.99 ZnClz(I.'t3P)2 19.03 BCl,( C,HsS) 54 18 Extrapolated values (ufp = 0).
c1-
TABLE I ELECTRIC L f O M E S T S AT 25' P
Found
Solvent
1OOw/z
AD/u,/2
Ad/uf2
23.90 21.45 21.90
D
0.17-0.56 .18- .43 .18- .86 .50- .79 .35- .86 .33-1.06 .30-0.93
36.2 30.7 35.5 31.0 37.0 1 7 1" 31.5"
0.32 .24
21.70 19.17 53.58
D D B I) B H
Boron trichloride-pyridine n-as prepared by mixing carbon tetrachloride solutions of pyridine and boron trichloride. The product was dissolved in benzene and reprecipitated by the addition of petroleum ether. Triethylphosphine was prepared by the reaction of ethylmagnesium bromide with phosphorus trichloride; after hydrolysis the product was distilled in an atmosphere of nitrogen and added to an aqueous solution of zinc chloride to yield dichlorobis-( triethylphosphine)-zinc. The precipitate %-as washed with ether and dried over sulfuric acid. C.P. benzene was refluxed over phosphoric anhydride and distilled. Dioxane was purified by the method described by Fieser.2 The product was distilled from sodium. Dielectric constant and density measurements and calculations of electric moments were carried out as in previous ~ o r k . 3 With the exceptions noted, the dielectric constant/ w i g h t fraction ratios listed in Table I are average values. The refractions were taken as the sum of the values for the base and the metal chloride. A value of 19 ml. was estimated for zinc chloride from the refractions listed for magnesium, cadmium and mercury chlorides in Landolt-Bornstein.' The 'distortion polarizations were taken as 1.10 .TI RD.
Discussion The agreement bet'ween the values obtained for the moment of dichlorobis-(P-picoline)-zinc in benzene, 9.53, and in dioxane, 9.54, indicates that dioxane exerts no specific solvent effect on t'he moments of these addition compounds. The moment's of the zinc chloride complexes are in t'he expected order: ypicoline > p-picoline > pyridine > a-picoline. The difference between the moments obt'ained for the a-picoline and pyridine complexes, 0.55 Debye, is equal to the calculated difference for these tet'rahedral molecules. It is not possible to make quantitative calculations of the moments of t'he a- and I!-picoline complexes as these values depend on the :favored (unknown) relative orientations of the pyridine rings, which are affect'ed by t'he steric requirements of the methyl groups. The moment3 observed for dichlorobis-(triet,hylphosphine)-zinc, 7.57, compares to the value 10.7 reported by Jensenj for dichlorobis-(triethylphosphine)-platinum(I1). Taking into account the configurations of these complexes, tetrahedral for zinc and cis square planar for platinum, the sum of the R3P-Zn and Zn-C1 moments is 6.58, compared to 7.57 for the sum of the R&Pt and I't-C1 vectors. This difference, 1.0 Debye, is not surpi*ising in the light of the greater stability of the platinum complexes compared to those of zinc. It' is expected that, the P-Pt u-bond
.26
.35 .22 .32 35
P9m
1807 1695 1948 1943 2030 1285 1200
Pu
74 85 85 85 85 110
51
Debyes
9 8 9 9 9 7 7
20 & 0 04 86 + 04 54 i 04 53 i 04 75 d= .1 57 1 50 i. 04
*
mill have a greater covalent character and therefore a greater polarity than the P-Zn bond. The difference suggests that there is no appreciably greater double bond character (which decreases bond polarity) in the phosphorus-to-platinum than in the phosphorus-to-zinc bond. The moments obtained reveal an anomaly in the relative polarities of zinc complexes and boron complexes. The moments of boron trichloridetrimethylamine and boron trichloride-trimethylphosphine are 6.23 and 7.03, respectively.'j These values indicate that the P-B bond is more polar than the N-B bond. It is not possible t o determine the moment of a dichlorobis-(trialky1amine)-zinc complex because of solubility limitations. The moment of boron trichloride-pyridine is 1.27 Debyes larger than that of boron trichloridetrimethylamine. If this difference (multiplied by 1.15 for the tetrahedral bis complex) holds also for the addition compounds of zinc chloride, the moment of dichlorobis-(triethylamine)-zinc is expected to be 7.8, compared to the observed moment of dichlorobis-(triethylphosphine) -zinc, 7 3 7 . This indicates that the P-Zn bond is slightly less polar than the S-Zn bond. Partiai I'=Zn double bond character could account for this, but zinc is not expected to use electrons from its completed third shell in forming n-bonds. ( 6 ) G. A I , Phillips, 1. S. Hunter and L E. Sutt i n I C h e m S o c , 146 (1945).
THE EFFECT OF UREA O S T H E COSFIGURATION OF POLYT'ISYLPYRROLIDOSE BY IRVING A I . KLOTZ AND JOEL It7, R r
,>ELL
Department of Chemistry, Sorthicestern Unzversity I.-z n?islon Illinois Received Januaru 6 , 1961
The synthetic polymer poly\-iii\-lpyrrolidone (PT'P) mimics protein behavior in a numbe? of
1
(2) L. Fieser, "Experiments in Organic Chemistry," D. C . Heath and Co., Boston, Mass.. 1911, p. 369. cCusker and H. S.Xakowski, J . Am. C h e m .
respects. For example it form? cvmpleses u-ith many types of small m~leciile,~-.' although u-ith
Soc., 79, 5188 ( 1 9 5 7 ) . f.1) Lmdolt-Bornstein,
(1) H. Bennhold and R . Schubert, Z. g e s . E r p t l . M e d . . 113, 722 (1943). ( 2 ) C. Wunderly, Arztl. Forsch., I , I , 29 (1950). (3) W.Scholtan, Makromol. C h e m . , 11, 131 (1953).
"Physikalisoh-Chemische Tabellen," wards Bros., -4n.n Arbor, Mich., 1943, vol. 2. ' 5 ) K. -4. Jenaen, 2. anorg. allgem. Chem., 229, 225 (1936).
Fd-
