VERIFICATION OF INFRARED VIBRATIONAL FREQUENCIES ASSOCIATED WITH AZlRlDlNE RING
The characteristic infrared frequencies of Ai-substituted aziridines were summarized b y Spell (IO) as follows: ring C-H stretching; 3040-3090 em-' (asymmetrical stretching vibrations) , 2979-3005 cm-l (symmetrical stretching vibrations) ; symmetrical-ring breathing vibration; 1250-1360 em-'; ring CHZ wagging; 1150-70 cm-'; ring deformation and CHz rocking modes; 745-860 em-'. Because data from deuterated aziridines and vibrational analyses of N-substituted aziridines were previously not available, some of these assignments are strictly empirical. -1pplying Hooke's law (9) and assuming that a C-H bond and a C-D bond have the same force constant, the ratio of the C-H to C-D frequency can be calculated to be 1.38. Thus h'-phenylaziridine-2-dz can be used to verify the various carbon-hydrogen vibrations. The following infrared data in em-1 were obtained from Nphenylaziridine-242: Methylene group CHz CD? rCH IrCD
CH, stretching Asym Sym 2890 3060 2170 2310 1.38 1.33
CH, wag CHZrock 1170 898 834 660 1.40 1.36
The TCHITCDratios are all in very good agreement with those calculated b y Hooke's law. Therefore, the empirically
assigned CH2 stretching, CH2 wagging, and CHZrocking vibrational frequencies of the aeiridine ring have now been verified b y isotopic data. The fact that the ring breathing vibrations mere correlated with Hammett sigma values also verifies their assignments. LITERATURE CITED
Arnold, J. T., Packard, U.E., J . Chem. Phys., 19, 1608 (1951). Dyall, L. K., Aust. J . Chem., 17,419 (1964). Heathcote, C., Can. J . Chem., 40, 1965 (1962). Klinck, R. E., Strothers, J. B., ibid., p 1071. Potts, W. J., Spectrochim. Acta, 21, 511 (196,5). Rae, I. D., Dyall, L. K., -4ust. J . Chem., 17, 1419 (1964). Rudesill, J. T., Severson, R. F., Pomonis, J. G., J . Org. Chem., 36, 3071 (1971). Saito, H., Nukada, K., Kobyaski, T., Morita, K., J . ilmer. Chem. Soc., 89, 6605 (1967). Silverstein, R. M., Sassler, G. C., "Spectrometric Identification of Organic Compounds," p 50, Wiley, New York, NY, 1963. Spell, H. L., Anal. Chem., 39, 185 (1967). Yamemoto, T., Reynolds, W. V., Hutton, H. AI., Schaefer, T., Can. J . Chem., 43,2668 (1965). RECEIVED for review October 8, 1971. Accepted April 6, 1972. Mention of a proprietary product or company name in this paper does not constitute an indorsement by the U. S. Department of Agriculture.
Preparation and Physical Properties of Some Methoxy- and Ethoxyacetates HENRY F. LEDERLE' and DAVID A. CSEJKA Olin Corp., New Haven, CT 06504
Esters of methoxy- and ethoxyacetic acid with glycols or glycol ethers were prepared and evaluated. The physical properties determined were viscosities (212", 122', loo", and -4OoF), ASTM viscosity slopes, pour points, effect on rubber, and hygroscopicity. The effect of molecular structure on physical properties i s discussed.
Conventional brake fluids are largely formulated from alkylene glycols and their ethers. Being hygroscopic, they soon deteriorate because of moisture absorption ( 3 ) . Even small amounts of moisture can lower t h e boiling point of a brake fluid to an extent where under severe usage, vapor lock with loss of braking action may result. llloisture also increases the low-temperature viscosities and causes sluggish brake response a t low temperatures. Two approaches to overcome t h e problem of hygroscopicity have recently been used. T h e first uses fluids which are less hygroscopic than glycols and glycol ethers (2). I n the second approach t h e moisture is chemically removed by reaction with the base fluid ( 5 ) . X new approach based on esters of methoxy- and ethoxyacetic acids is presented here. EXPERIMENTAL
Where available, reagent-grade chemicals were used for t h e ester syntheses. All other chemicals were high-quality commerTo whom cor7,espondence should be addressed
cia1 products. Starting materials were used as received Stoichiometric amounts of alkoxyacetic acid and glycol or glycol ether were refluxed in toluene using sulfuric acid as catalyst. After water no longer azeotroped in the Dean-Stark trap, calcium oxide or hydroxide sufficient to neutralize the sulfuric acid was added to the cooled product. After filtration, t h e product was stripped and distilled in vacuo through a vacuum-jacketed Vigreux column, 5.5 in. long. Elemental analyses (C, H ) in agreement with t h e theory were obtained and submitted for review. Physical properties were determined by ASTM methods except as follows: I n the pour point determination only one cooling bath, D r y Ice-acetone, was used. Reflux boiling point (Table IV) and effect on rubber were determined by SAE procedures (4). Briefly, t h e effect on rubber (rubber swell) was determined as t h e diameter increase of a standard SBR wheel cylinder cup (original diameter 1.1 in.) after heating to 120°C for 70 hr. For automotive brake fluids, the Society of Automotive Engineers specifies the following limits for t h e properties tested here: kinematic viscosities a t 212'F, 1.5 cSt minimum; a t 122°F) 3.5 cSt minimum; a t -40"F, 1800 cSt maximum; and rubber swell, 0.006-0.055 in. The hygro-
Journal of Chemical and Engineering Datc, Vol. 17, No. 3, 1972
395
scopicity tests of Table IV were performed at 80% relative humidity for 3.5 h r a t 75°F.
swell (Runs 1 through 4). Increased branching gives poorer ASTM slopes (Runs 3, 6, and 7). It also increases t h e effect on rubber and gives higher (poorer) viscosities at -40'F (e.g., Runs 4 vs. 8 or 2 vs. 5 ) . R u n 1 has an unusually high viscosity at -440°F. This may be caused by incipient loss of chain flexibility and free rotation because t h e relatively closely spaced ester groups in this molecule are beginning t o interfere with each other. Replacing t h e central methylene group in R u n 4 by an ether oxygen, R u n 10, results in poorer (higher)
DISCUSSION Diesters (Tables I and 11). Increasing the chain length of the glycol portion of the molecule produces more favorable (lower) ASThl viscosity slopes b u t poorer (higher) rubber
Table I.
Esters of Methoxyacetic Acid and Glycols
0
II
(CHa0CHzCO)zR (I)
2
R -(CHz)z-(CH2)3-
78 64
Bp, OC/mm 93/0,025 103-4/0.06
Refractive index, nZ5D 1.4373 1.4381
3 4
-(cH2)4--(CHz)s-
68 76
127-8/0.05 137-9/0.08
1,4405 1.4422
1.86 1.99
4.64 4.99
6.41 6.67
853
5 6 7 8
-CH(CHa)CHz-CH(CHa)CHzCHz-CH(CHz)(CHs)CH-CH~C(CH~)zCHz-
86 73 75 95
95-7/0.03 98- 108/0.06 99-108/0.06 117-19/0.05
1.4346 1.4370 1.4344 1.4381
1.60 1.79 1.65 1.79
4.17 4.35 4.60 4.99
6.09 6.21 6.72 7.08
3279 1890 2010 3461
158-61/0.07 9 -CHzC(CHs)zCHzOCC(CH3)zCHz76 136-40/0.04 10 -(CHz)zO (CHz)z81 a Not determined. * Traces of crystallization at .85OF.
1.4451 1.4442
3.14 11.60 19.60 0.88 2.14 6.11 9.00 9540 0.88
Yield,
Run no. 1
yo
Kinematic viscosity, est, O F 212 122 100 -40 1.58 4.18 5.94 2340 1.68 3.99 5.56 767
Pour Rubber ASTM point, swell, slope OF in. 0.95 -75 0.019 0.85 Below 0.028 - 85 0.83 Solid 0.040 0.80 Below 0.063 - 85* 0.95 - 65 0.041 0.86 -80 0.046 0.97 -55 0.060 0.92 -70 0.072
0
II
Table II.
-45 -60
0.050 0.029
Pour point,
Rubber swell, in. 0.055 0.093 0,062 0.043
Esters of Ethoxyacetic Acid and Glycols
0
/I
(CzH50CHzCO),R (11) Run no.
Yield,
R 7% 11 -(CHz)z85 12 -(cHZ)487 13 -CH(CHzOCHs)CHz-76 14 --(CHz)zO(CHz)z93 a Not determined. Crystallized.
BP, "C/mm 111-3/0.03 131-4/0.03 13&8/0.04 146-7/0.06
Table 111.
Refractive index, n26D 1.4344 1.4386 1.4370 1.4424
Kinematic ViScoSitY, CSt, 212 122 100 -40 4.35 1.58 5.66 1,673 1.90 4.70 6.57 a 1.91 5.65 8.41 10,480 2.17 5.75 6,896 8.40
ASTM slope 0.92 0.83 0.94 0.83
O F
-75 -5' -60 -65
Esters of Methoxyacetic Acid and Glycol Ethers 0
I/
CHaOCHzCOR (111)
Run no. 15
-(CHzCHzO)zC4Ho
53
16 17
-(CHzCHz0)3CH3 -(CHzCHzO)3ChH,
73
R
- (CHzCHzO)aCH, -(CHzCHzO)ICzHj -(CHzCHzO )7mCH3
18
19 20 21 22 0
-[
CH(CH3)CHzOIzCH3
-CH(CHa)CHzOCH2CH20C4Hg
Distilled twice.
396
Not determined.
Yield,
7c
74
48" 43" 63
Bp, "C/mm 96-103/0.15 105-10/0.05 129-31/0.2
4ga
137-43/0.05 144-5/0.07 175-253/ 0.25-0.19 73-6,'O.l
51
103-4/0.4
Refractive Pour Rubber index, Kinematic viscosity, est, "F ASTM point, swell, 122 100 -40 slope O F in. n z 6 ~ 212 1.4326 1.29 2.60 3.60 22 1 0.86 Below 0.159 -90 1.4389 1.43 3.34 473 0.82 -85 0.059 4.89 565 0.82 Below 0.154 1.4390 1.69 3.96 5.23 -85 1.4438 1.88 4.68 -85 0.046 7.09 1206 0.87 1,4432 1.90 4.75 - 80 0,063 6.57 1291 0.82 h 0.70 0.019 1.4544 3.70 10.57 15.60
+
1.4357
1.08
2.30
2.90
177
0.93
1.4304
1.30
2.80
3.60
211
0.86
Started to crystallize a t +35OF.
Journal of Chemical and Engineering Data, Vol. 17, No. 3, 1972
Below -85 Below -90
0.165 0.195
Table IV.
Hygroscopicity Tests
Reflux bp, OF Dry Humidified
Fluid SAE compatibility fluid Average of seven cominercial fluids R U I 2, ~ Table I Run 16, Table I11
Water absorbed,
358
283
3.03
501 566 364
308 529 468
2.56
