THE JOURNAL OF
PHYSICAL CHEMISTRY (Regzstered zn U . 8. Patent Oflice)
(8Copurwht, 1983, by the Amerzcan Chemzcal Soczety)
V O L C6 ~ 7 , KUMBER 11
KOVEMBER 15, 1963
HEAT CAjPL4CHTIESFROM 11 TO 305’K. ,4ND ENTROPIES OF L-ARGININE*HCI, L-HISTIDINE.HCl, AND L-LYSINE.HCll BY XRTIXR G. COLE,JOHN 0. HUTCHEM, AND J. W. STOUT Departments of Chemistry and Physiology and the Institute for Study of Metals, University of Chicago, Chicago, Illinois Received J u l y 1, 1063 Heat capacities have been measured from 11 to 305°K. for L-arginine.HC1, L-histidine.HC1, and L-lysine.HC1. , -(Po - H o o ) / Tare tabulated as a function of temperature from 10 to Values of C,”, So, ( H O - H B ” ) / T and 310°1-isomer previously de~ c r i b e d . ~They were crystalline, as evidenced by microscopic examination in polarized light. Each was dried to constant weight in vacuo ( < l o - ” mm.) in a system trapped with liquid nitrogen. No abnormal values of heat capacity were observed in the neighborhood of the ice point. Experimental Methods and Calculations.-The methods for measuring heat capacities have been deacribed in detail.5 The calorimeter used was the one with six radial fins, and the thermometer was the one bearing the 1abora)torydesignat.ion “H.” Sample weights in vucuo were 81.008 g. for ~-argimnine.HCl, 68.656 g. for L-histidine.HC1, and 65.611 g. for L-lysine.HC1. In each case, the heat capacity of the empty calorimeter repre(1) The heat capacity studies reported here were entirely su’pported by the U. S. Atomic Energy Commission. Ancillary studies were supported by a grant from the National Institutes of Health and b y the Wallace A. and Clara M. Abbott Memorial Fund of the University of Chicago. support of the cryogenic facilities by the X’ational science Foundationis gratefully acknowledged. (2) H. 31.Huffman, S.W. Fox, and E. L. Ellis, J. Am. Chem. Soc., 59,2144 (1937). ( 3 ) H. M. Huffmm and E:. L. Ellis, i b i d . , 59, 2150 (1937). U0. J. 0. Hutchens, A . G. ‘Cole,and J. W. Stout, i b i d . , 82, 4813 (1960). ( 5 ) A. G. Cole, J. 0. Hutchens. R. A. Robie, and J. W. Stout, ibid., 82, 4807 (1960).
sented approximately 40% of the total heat capacity over most of the temperature range employed.
Results The experimentally measured quantities ( A H I A T ) are listed in Table I for L-argiiiine.HC1 in the chronological order in which they were obtained. From these, the thermal history of the amino acid can be deduced. Where AT for an individual experiment is not obvious from Table I, the limits previously described4 apply. Equivalent data are given in Table I1 for L-histidineeHC1 and in Table I11 for L-lysine. HC1. Calculations of curvature corrections for individual measurements below 5OOK. indicated that none were TABLE I HEAT CAPACITYOF L-AROIKINE.HC~ IK CAL. D E G . - ~ MOLE-1 [O’C. = 273.15’K.; mol. wt. CeHI6O2S4C1 = 210.681 T , OK.
AH/AT
T , “K.
AH/AT
T , OK.
AH/AT
298.76 297.67 53.00 58.89 64.11 69.77 75.29 80.67 10.91 11.94 13.01 14.19 16.04 17.72 19.58 21.41 23.48 25.94 28.81 31.92 35.11 38.52 42.27
62.70 62.31 14.93 16.86 18.49 20.12 21.56 22.99 0.716 0.879 1.101 1.358 1.809 2.266 2.800 3.368 4.066 4.932 6.988 7.164 8.395 9.691 11.09
46.34 50.71 79.80 84.31 89.30 94.76 100.26 105.78 111.24 115.91 121.60 127.18 132.97 138.65 144.14 149.82 158.03 163.58 169.47 176,36 181.42 187.58 193.03
12.60 14.15 22.72 23.94 25.11 26.31 27.44 28.60 29.72 30.63 31.72 32.75 33.88 34.94 35.92 36.92 38.39 39.36 40.39 41.46 42.46 43.48 44.47
198.90 204.97 210.98 217.35 220.68 226.75 232.73 234.96 240.53 246.54 252.53 258.88 265.41 271.60 278.32 284.45 290.66 297.32 304.16 270.15 276.17 284.45 291.69
45.44 46.44 47.51 48.55 49.09 50.18 51.22 51.57 52.4’7 53.57 54.50 55.68 56.78 57.93 59.086 60.07 61.12 62.26 63.316 57 ,410 58.33 60.35 61.61
2245
ABTHURG. COLE,JOHX 0. HUTCHESS, ASD J. W. STOUT
2246
TABLEI1 HEATCAPACITY OF L-HIGTIDINE.HC~ IN CAL. D E G . - ~ MOLE-1 [OOC. = 273.15"K.; mol. wt. C6HloOnS~C1 = 191.631 T,O
I L
301.66 57.85 63.17 68.66 74.34 79.50 84.26 89.54 94.67 100.03 105.55 111.17 116.88 120.85 126.52 132.34 137.74 143.34 148.89 152.92 158.60 164.14
AH/AT
60.95 16.37 17.94 19.44 20.86 22.13 23.29 24.48 25.49 26.54 27.59 28.66 29.70 30.39 31.36 32.39 33.34 34.23 35.17 35.83 37.01 37.68
T,
OK.
169.79 175.56 181.39 186.87 192.77 198.76 204.60 210.24 220,93 226.90 233.12 239.37 245.78 251.42 258.10 264.72 271.13 277.70 284.24 290.99 297.86 305.29
AH/AT
T , OK.
AH/AT
38.62 39.59 40.51 41.30 42.32 43.26 44.24 45.13 46.90 47.83 48.75 49.82 51.07 51.76 52.93 54.14 55.21 56.17 57.27 58.37 59.68 60.69
11.39 12.39 13.61 15.01 16.54 18.22 20.17 22.38 24.78 27.22 29.87 32.85 36.25 40.08 44.31 48.90 54.09 267.25 272.70 279.44 285 97
0.615 0.778 1.031 1.361 1,783 2.286 2.907 3.667 4.498 5.451 6.477 7.637 8.938 10.38 11.91 13.53 15.20 54.25 55.34 56.33 57.53
~
TABLE111 HEATCAPACITY OF L-LYSINE.HCIIN CAL. D E C . - ~ MOLE-1 [O'C. = 273.15'K.; mol. wt. CQHI6O2N2C1 = 182.661 T,'IC.
AH/AT
T , OK.
299.68 51.56 56.28 61.70 67.00 72.14 76.92 81.27 85.66 90.71 95.88 101.20 106.60 112.04 117.51 119.05 124.52 130.03 135.41 141.05 146.66 152.16 157.92
57.50 13.36 14.76 16.34 17.78 19.os 20.26 21.36 22.44 23.53 24.56 25.65 26.71 27.76 28.78 29.04 30.00 30.92 31.85 32.76 33.6.5 34.52 35.41
163.74 166.84 172.57 178.38 183.94 189.50 195.11 200.97 204.87 210.48 216.29 223.09 229.67 235.30 241.12 244.52 250.23 256.07 262.03 268.08 274.02 280.04 286.05 291.95
AH/AT
36.31 36.76 37.63 38.52 39.32 40.10 40.94 41.78 42.32 43.20 44.02 45.06 46.42 46.89 47.80 48.29 49.33 50.23 51.07 52.09 53.02 53.98 55.00 56.00
T , OK.
298.32 308.14 10.82 11.72 12.76 13.93 15.25 16.71 18.48 20.39 22.53 24.90 27.36 30.02 33.07 36.54 40.42 44.46 48.65 265.42 270.53 276.49 284.13
AH/AT
57.08 58.41 0.729 0.875 1.076 1,332 1.637 2.008 2.486 3.036 3.699 4.467 5.286 6.196 7.254 8.436 9.719 11.04 12.38 51.63 52.49 53.84 54.65
required within the limits of accuracy claimed. The values of A H I A T are therefore equal to C, a t the stated temperatures. The thermodynamic properties of L-arginine * HCl, derived from the data of Table I, are given in Table IV. Equivalent data for L-histidine 'HC1 aiid klysine * HC1 are presented in Tables V and VI, respectively. The ice point was taken as 273.15'K. and 1 cal. = 4.1840 absolute joules. From the values of S'298.15 given in Tables IV-VI and the entropies of the elements,6 we have calculated (6) National Bureau of Standards Circular 500, "Selected Values of Chemical Thermodynamic Properties," U. S. Government Printing Office, Washington, D. C., 1952.
Vol. 6
TABLEI V THERYODYNAMIC PROPERTIESOF L-ARQININE.HC~ IN DEG.-' MOLE-^ T , OK.
SO
CPO
Ho
- Ho' T
10
15 20 25 30 35 40 45 50 55 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 273.15 298.15 310.15
0.556 1.549 2.928 4.592 6.432 8.344 10.26 12.12 13.90 15.60 17.22 20.18 22.82 25.22 27.41 29.46 31.42 33.31 35.17 36.98 38.74 40.49 42.22 43.92 45.62 47.30 49.02 50.72 52.43 54.14 55.86 57.60 59.32 61.01 62.68 64.33 58.14 62.37 64.36
0.202 0.598 1.226 2.053 3.052 4.186 5.426 6.742 8.112 9.517 10.94 13.83 16.70 19.52 22.30 25.01 27.65 30.24 32.78 35.27 37-71 40.11 42 47 44.80 47.10 49.36 51.60 53.82 56.02 58.19 60.35 62.49 64.61 66.72 68.82 70 90 63.16 68.43 70.93 I
~
0.149 0.436 0 I880 1.452 2.128 2.879 3.682 4.517 5.366 6.220 7.069 8.735 10.33 11.86 13.30 14.68 15.99 17.25 18.47 19.64 20.78 21.89 22.97 24.03 25.06 26.08 27.09 28.08 29.06 30.02 30.98 31.94 32.89 33.83 34.76 35.69 32.24 34.59 35.70
-(Fo
CAL.
- Hn') T
0,053 .162 .345 .601 .924 1.308 1,744 2.226 2.746 3.297 3.875 5.090 6.362 7.668 8.992 10.33 11.66 12.99 14.31 15.63 16.93 18.22 19.51 20.78 22.04 23.28 24.52 25.74 26.96 28.17 29.36 30.55 31.73 32.90 34.06 35.22 30.92 33.84 35.23
the eiitropies of formation of these compounds. They are (A&0298.~6 in cal. mole-' deg.-'): -341.01 for L-arginine aHC1, -242.54 for L-histidine HC1, and - 300.46 for L-lysiiie.HC1. Discussion Huffman and Ellis3 reported XozQs.lfor D-arginine to be 59.9 cal. mole-' deg.-', or 8.5 cal. mole-' deg.-l less than the value of 8'295.16 reported here for L-arginine .HCl. Strictly comparable data for hydrochlorides of other substances are lacking. I n the following two cases, unfortunately, all available amino groups are converted to the hydrochloride, whereas in the case of L-argiiiiiie.HC1 oiily one of the two basic groups is neutralized, leaving a zwitterionic substance with the coiisequeiit ability for strong ionic binding in the crystal. For glutamic acid, Huffman aiid Borsook' give Xo2Qs.1a value of 45.7 cal. mole-' deg.-', while in this laboratory it was found to be 44.98 cal. mole-l deg.-1.8 Huffman, Ellis, aiid Borsookg re(7) H. M. Huffman and H. Borsook, J . A m . Chem. Soc., 54, 4297 (1932). (8) J. 0. Hutehens, -4. G. Cole, R. A. Robie, and J. W. Stout, J . Btol.
Chem., in press. (9) H.M. Huffman, E. L. Ellis, and H. Borsook, J . Am. Chem. Soc., 62, 297 (1940).
HEATCAPACITIES AND EXTROPIES OF AMINOACIDS
Kov., 1963
TABLE V THERMODYNANIC PROPERTIES OF L-HISTIDINE.HC~ in DEG.
10 15 20 25 30 35 40 45 50 55 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 2'73.15 298.15 310.15
17o,
S O
0.409 1.360 2.851 4.621 6.522 8.455 10.34 12.16 13.89 15.49 117.01 19.79 22.28 24,53 26.55 28.45 30.25 31.99 33.69 35.35 37.00 38.63 40.24 41.86 43.48 45.09 46. TO 48.31 49.93 51 58 53.25 54.94 56.62 58.29 59,9-1 61.58 55.47 59.64 61.60
TABLE VI THERMODYNAMC P R O P E R T I E S O F L-LYsIP~E.HC~ I N GAL.
0.136 0.458 1.046 1.869 2.879 4.030 5.283 6.606 7.977 9.377 10.79 13.63 16.44 19.19 21.88 24.50 27.06 29.55 31.98 34.36 36.69 38.99 41.24 43.46 45.65 47.81 49.94 52.05 54.14 56.21 58.27 60.31 62.34 64.36 66.36 68.35 60.94 65.99 68.38
DEI:.
KOLE-'
MOLE-1
H a - Ho0
T ,OK.
CAL.
2237
T
0. loa .343 .777 1.366 2.066 2.841 3.661 4.505 5.357 6.207 7.045 8.671 10.22 11.69 13.07 14.39 15.63 16.82 17.97 19.07 20.14 21.18 22.19 23.19 24.16 25.12 26.06 27.00 27.92 28.83 29.74 30.64 31.54 32.43 33.32 34.21 30.92 33.16 34.22
-(Fo
- Ho')
H'
T
T ,OK.
CPO
0.034 ,115 .269 .503 .813 1.189 1.621 2.101 2.620 3.170 3.747 4.956 6.216 7.505 8.808 10.12 11.42 12.72 14.01 15.29 16.55 17.80 19.04 20.27 21.48 22.69 23.88 25.06 26.22 27.38 28.53 29.67 30.80 31.92 33.04 34.14 30.03 32.83 34.16
10 15 20 25 30 35 40 45 50 55 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 273.15 298.15 310.15
0.588 1,576 2,9221 4.497 6.187 7 I905 9.587 11.22 12.82 14.37 15.85 18.57 21.06 23.36 25.42 27.36 29.21 30.96 32.60 34.19 35.75 37.27 38.74 40.19 41.65 43.12 44.60 46.11 47.64 49.19 50.77 52.38 54.00 55.68 57.42 59.24 52.88 57.10 59.27
ported So298.1 for glutamic acid.HC1 to ble 59.33, which is approximately 14 cal. mole-I deg.-J greater than that of the parent amino acid. Huffrnan and Foxlo found So298.1 to be 46.2 cal. mole-l deg.-l for DL-ornithine ; Huffman, Ellis, and Borsook9 reported a value of 70.25 cad. mole-1 deg.-l for ornithine dihydrochloride. The difference is about 12 cal. mole--1deg.-l per molecule of HCI. Since the formation of a hydirochloride produces such different effects on the entropies of these three c
(IO) H. 31. Huffrnan and S.Fox, J . Am. Chem Soc., 62,3464 (1940).
80
0.224 ,633 1.264 2.082 3.051 4.134 5.300 6.524 7.789 9.084 10.40 13.05 15.69 18.31 20.88 23.39 25.85 28.26 30.62 32.92 35.18 37.39 39.56 41.69 43.79 45.86 47.90 49.92 51.91 53,89 55.85 57.79 59.73 61.65 63.57 65.48 58.40 63.21 65,5l
- Ho' T
0.163 ,456 ,899 1.458 2.104 2,810 3.553 4.315 5.086 5,860 6.631 8.146 9.606 11.01 12.35 13.63 14.85 16.02 17.15 18.23 19.28 20.29 21.27 22.23 23.17 24.08 24.98 25.86 26.74 27.61 28.47 29.32 30.18 31.03 31.88 32.73 29.59 31.72 32.74
- ( F O
- Ho") T
0.061 .i77 .366 .624 ,946 1.323 1.747 2.209 2.704 3.225 3.768 4.904 6.088 7.301 8.530 9.768 11.01 12.24 13.47 14.69 15.90 17.10 18.29 19.46 20.63 21.78 22.92 24,05 25.17 26.28 27.35 28.47 29.55 30.62 31.69 32.75 28.81 31.49 32.76
substances, it would appear that the estimates of other thermal properties, such as the heat of combustion of the hydrochlorides from data for the parent compounds, might be subject to large errors. Consequently, although Huffman, Fox, and Ellis2 reported the heat of combustion of D-arginine, we have not felt sufficiently confident of the correction to be made for the addition of an HC1 molecule to calculate a value for the enthalpy of formation of L-arginine.HC1. No enthalpy values are available for lysine or histidine, nor are there any previous reports of heat capacities for these substances.
