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Urea

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Gas phase thermochemistry data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), UV/Visible spectrum, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity Value Units Method Reference Comment
Deltafgas-235.5 ± 1.2kJ/molCcbKabo, Miroshnichenko, et al., 1990see Simirsky, Kabo, et al., 1987

Condensed phase thermochemistry data

Go To: Top, Gas phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), UV/Visible spectrum, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity Value Units Method Reference Comment
Deltafsolid-333.11 ± 0.69kJ/molCcbKabo, Miroshnichenko, et al., 1990see Simirsky, Kabo, et al., 1987; ALS
Deltafsolid-320.2 ± 2.0kJ/molCcbContineanu, Wagner, et al., 1982ALS
Deltafsolid-333.39 ± 0.17kJ/molCcbJohnson, 1975ALS
Deltafsolid-333.3 ± 0.2kJ/molCcbHuffman, 1940ALS
Deltafsolid-323.6kJ/molCcbSchmidt and Becker, 1933ALS
Quantity Value Units Method Reference Comment
Deltacsolid-635. ± 8.kJ/molAVGN/AAverage of 8 values; Individual data points
Quantity Value Units Method Reference Comment
solid,1 bar104.26J/mol*KN/AAndersson, Matsuo, et al., 1993DH
solid,1 bar104.93J/mol*KN/AKozyro, Dalidovich, et al., 1986DH
solid,1 bar105.4J/mol*KN/AParks, Huffman, et al., 1933Extrapolation below 90 K, 33.18 J/mol*K.; DH
solid,1 bar172.J/mol*KN/AGibson, Latimer, et al., 1920Extrapolation below 86 K, no details.; DH

Constant pressure heat capacity of solid

Cp,solid (J/mol*K) Temperature (K) Reference Comment
92.79298.15Andersson, Matsuo, et al., 1993T = 15 to 310 K.; DH
94.0304.7Gambino and Bros, 1988T = 303 to 413 K.; DH
93.08298.15Kozyro, Dalidovich, et al., 1986T = 5 to 400 K. Cp = 38.43 + 4.98x10-2T + 7.05x10-4T2 - 8.61x10-7T3 (240 to 400 K).; DH
90.0298.15Sasaki and Yokotake, 1966T = 90 to 298 K.; DH
93.14298.15Ruehrwein and Huffman, 1946T = 19 to 318 K.; DH
68.6293.Campbell and Campbell, 1940DH
93.64298.0Parks, Huffman, et al., 1933T = 93 to 298 K. Value is unsmoothed experimental datum.; DH
115.5298.0Gibson, Latimer, et al., 1920T = 86 to 300 K. Value is unsmoothed experimental datum.; DH

Phase change data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Kenneth Kroenlein director
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity Value Units Method Reference Comment
Tfus406. ± 3.KAVGN/AAverage of 8 values; Individual data points
Quantity Value Units Method Reference Comment
Ttriple407.9KN/AFerloni and DellaGatta, 1995Uncertainty assigned by TRC = 0.2 K; TRC
Ttriple408.KN/AKabo, Miroshnichenko, et al., 1990, 2Uncertainty assigned by TRC = 0.00001 K; TRC
Ttriple405.8KN/AKozyro, Dalidovich, et al., 1986, 2Uncertainty assigned by TRC = 0.1 K; TRC
Ttriple405.8KN/AVogel and Schuberth, 1980Uncertainty assigned by TRC = 0.2 K; TRC
Quantity Value Units Method Reference Comment
Deltasub95.5 ± 0.3kJ/molGSEmel'yanenko, Kabo, et al., 2006Based on data from 358. - 402. K.; AC
Deltasub98.6kJ/molN/ADe Wit, Van Miltenburg, et al., 1983AC
Deltasub87.65 ± 0.88kJ/molVSuzuki, Onishi, et al., 1956ALS

Enthalpy of sublimation

DeltasubH (kJ/mol) Temperature (K) Method Reference Comment
94.6 ± 2.2370.MEZaitsau, Kabo, et al., 2003Based on data from 329. - 403. K.; AC
95.1 ± 2.2350.MEZaitsau, Kabo, et al., 2003Based on data from 329. - 403. K.; AC
94.6 ± 0.5350.CZaitsau, Kabo, et al., 2003AC
97.6 ± 1.0354.CKabo, Miroshnichenko, et al., 1990see Simirsky, Kabo, et al., 1987; ALS
90.9381.N/AFerro, Barone, et al., 1987AC
87.7357.N/AStephenson and Malanowski, 1987Based on data from 345. - 368. K.; AC
96.9351.TE,MEDe Wit, Van Miltenburg, et al., 1983Based on data from 338. - 362. K.; AC
95.4361.N/ATrimble and Voorhoeve, 1978AC
87.9 ± 2.1356.N/ASuzuki, Onishi, et al., 1956, 2Based on data from 345. - 368. K. See also Jones, 1960 and Cox and Pilcher, 1970.; AC
88.2357.N/ABradley and Cleasby, 1953See also De Wit, Van Miltenburg, et al., 1983.; AC

Enthalpy of fusion

DeltafusH (kJ/mol) Temperature (K) Method Reference Comment
14.790406.5N/ADella Gatta and Ferro, 1987DH
13.900405.8N/AKozyro, Dalidovich, et al., 1986DH
14.500406.N/AGambino and Bros, 1988DH
13.610405.8N/AVogel and Schuberth, 1980, 2DH
14.6407.2DSCRai and Rai, 1999AC
13.6405.2DSCJamróz, Palczewska-Tulinska, et al., 1998AC
14.6406.7DSCRai and Rai, 1998AC
15.03407.9DSCFerloni and Gatta, 1995AC
12.93408.1N/AKabo, Miroshnichenko, et al., 1990AC
13.9405.8N/AKozyro, Dalidovich, et al., 1986, 2AC

Entropy of fusion

DeltafusS (J/mol*K) Temperature (K) Reference Comment
36.4406.5Della Gatta and Ferro, 1987DH
34.25405.8Kozyro, Dalidovich, et al., 1986DH
35.7406.Gambino and Bros, 1988DH
33.54405.8Vogel and Schuberth, 1980, 2DH

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:


Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), UV/Visible spectrum, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
B - John E. Bartmess
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

CH3N2O- + Hydrogen cation = Urea

By formula: CH3N2O- + H+ = CH4N2O

Quantity Value Units Method Reference Comment
Deltar1514. ± 12.kJ/molCIDCMa, Wang, et al., 1998gas phase; H and S (20.5±1.8 eu) directly from kinetic method; B
Deltar1517. ± 11.kJ/molG+TSTaft, 1987gas phase; value altered from reference due to change in acidity scale; B
Deltar1495. ± 8.8kJ/molEIAEMuftakhov, Vasil'ev, et al., 1999gas phase; B
Quantity Value Units Method Reference Comment
Deltar1488. ± 13.kJ/molH-TSMa, Wang, et al., 1998gas phase; H and S (20.5±1.8 eu) directly from kinetic method; B
Deltar1487. ± 10.kJ/molIMRETaft, 1987gas phase; value altered from reference due to change in acidity scale; B

Urea + 2-Oxetanone, 4-methylene- = N-(aminocarbonyl)-3-oxobutyramide

By formula: CH4N2O + C4H4O2 = N-(aminocarbonyl)-3-oxobutyramide

Quantity Value Units Method Reference Comment
Deltar-106.4kJ/molKinLopatin, Popov, et al., 1992liquid phase; solvent: Solution; ALS

6Urea = 1,3,5-Triazine-2,4,6-triamine + 3Carbon dioxide + 6Ammonia

By formula: 6CH4N2O = C3H6N6 + 3CO2 + 6H3N

Quantity Value Units Method Reference Comment
Deltar469.4kJ/molEqkRukevich and Zagranichnyi, 1971liquid phase; ALS

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Mass spectrum (electron ionization), UV/Visible spectrum, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

Proton affinity at 298K

Proton affinity (kJ/mol) Reference Comment
868.4 ± 2.5Zheng and Cooks, 2002MM
873.5 ± 5.0Wang, Ma, et al., 1998m-bromoaniline; p-fluorobenzamide; MM
873.5 ± 5.0Wang, Ma, et al., 1998T = T(eff) = 410-560 KK; Acrylamide;m-Bromoaniline; MM

Gas basicity at 298K

Gas basicity (review) (kJ/mol) Reference Comment
838.7 ± 3.0Zheng and Cooks, 2002MM
846.1 ± 5.0Wang, Ma, et al., 1998m-bromoaniline; p-fluorobenzamide; MM
841.6 ± 5.0Wang, Ma, et al., 1998T = T(eff) = 410-560 KK; Acrylamide;m-Bromoaniline; MM

Protonation entropy at 298K

Protonation entropy (J/mol*K) Reference Comment
9.4Zheng and Cooks, 2002MM
-1.9Wang, Ma, et al., 1998T = T(eff) = 410-560 KK; Acrylamide;m-Bromoaniline; MM

Ionization energy determinations

IE (eV) Method Reference Comment
9.7PEDebies and Rabalais, 1974LLK
10.27 ± 0.05EIBaldwin, Kirkien-Konasiewicz, et al., 1966RDSH
9.8PEBieri, Asbrink, et al., 1982Vertical value; LBLHLM
10.28PEDougherty, Wittel, et al., 1976Vertical value; LLK
10.33PEMines and Thompson, 1975Vertical value; LLK
10.15PEMeeks, Arnett, et al., 1975Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
CH2NO+12.90?EILoudon and Webb, 1977LLK

De-protonation reactions

CH3N2O- + Hydrogen cation = Urea

By formula: CH3N2O- + H+ = CH4N2O

Quantity Value Units Method Reference Comment
Deltar1514. ± 12.kJ/molCIDCMa, Wang, et al., 1998gas phase; H and S (20.5±1.8 eu) directly from kinetic method; B
Deltar1517. ± 11.kJ/molG+TSTaft, 1987gas phase; value altered from reference due to change in acidity scale; B
Deltar1495. ± 8.8kJ/molEIAEMuftakhov, Vasil'ev, et al., 1999gas phase; B
Quantity Value Units Method Reference Comment
Deltar1488. ± 13.kJ/molH-TSMa, Wang, et al., 1998gas phase; H and S (20.5±1.8 eu) directly from kinetic method; B
Deltar1487. ± 10.kJ/molIMRETaft, 1987gas phase; value altered from reference due to change in acidity scale; B

IR Spectrum

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), UV/Visible spectrum, References, Notes

Data compiled by: Coblentz Society, Inc.

Data compiled by: Timothy J. Johnson, Tanya L. Myers, Yin-Fong Su, Russell G. Tonkyn, Molly Rose K. Kelly-Gorham, and Tyler O. Danby


Mass spectrum (electron ionization)

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, UV/Visible spectrum, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

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Mass spectrum
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Additional Data

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Owner NIST Mass Spectrometry Data Center
Collection (C) 2014 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.
Origin Japan AIST/NIMC Database- Spectrum MS-NW-6843
NIST MS number 229591

All mass spectra in this site (plus many more) are available from the NIST/EPA/NIH Mass Spectral Library. Please see the following for information about the library and its accompanying search program.


UV/Visible spectrum

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Victor Talrose, Alexander N. Yermakov, Alexy A. Usov, Antonina A. Goncharova, Axlexander N. Leskin, Natalia A. Messineva, Natalia V. Trusova, Margarita V. Efimkina

Spectrum

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UVVis spectrum
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1.) Enter the desired X axis range (e.g., 100, 200)
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Additional Data

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Source Klotz and Askounts, 1947
Owner INEP CP RAS, NIST OSRD
Collection (C) 2007 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.
Origin INSTITUTE OF ENERGY PROBLEMS OF CHEMICAL PHYSICS, RAS
Source reference RAS UV No. 9317
Instrument Beckman quartz spectrophotometer
Melting point 132.7
Boiling point dec

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), UV/Visible spectrum, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Kabo, Miroshnichenko, et al., 1990
Kabo, G.Ya.; Miroshnichenko, E.A.; Frenkel, M.L.; Kozyro, A.A.; Simirskii, V.V.; Krasulin, A.P.; Vorob'eva, V.P.; Lebedev, Yu.A., Thermochemistry of urea alkyl derivatives, Bull. Acad. Sci. USSR, Div. Chem. Sci., 1990, 662-667. [all data]

Simirsky, Kabo, et al., 1987
Simirsky, V.V.; Kabo, G.J.; Frenkel, M.L., Additivity of the enthalpies of formation of urea derivatives in the crystalline state, J. Chem. Thermodyn., 1987, 19, 1121-1127. [all data]

Contineanu, Wagner, et al., 1982
Contineanu, I.; Wagner, L.; Stanescu, L.; Marchidan, D.I., Combustion and formation enthalpies of o-phenylenediamine, urea and 2-benzimidazolone, Rev. Roum. Chim., 1982, 27, 205-209. [all data]

Johnson, 1975
Johnson, W.H., The enthalpies of combustion and formation of acetanilide and urea, J. Res. NBS, 1975, 79, 487-491. [all data]

Huffman, 1940
Huffman, H.M., Thermal Data. XII. The heats of combustion of urea and guanidine carbonate and their standard free energies of formation, J. Am. Chem. Soc., 1940, 62, 1009-1011. [all data]

Schmidt and Becker, 1933
Schmidt, V.A.; Becker, F., Die Bildungswarme von Nitrocellulofen, Nitroglycerin und anderen widuigen Beltandteilen von Treibmitteln, Z. Gesamte Schiess Sprengstoffwes., 1933, 33, 280-282. [all data]

Andersson, Matsuo, et al., 1993
Andersson, O.; Matsuo, T.; Suga, H.; Ferloni, P., Low-temperature heat capacity of urea, Int. J. Thermophys., 1993, 14(1), 149-158. [all data]

Kozyro, Dalidovich, et al., 1986
Kozyro, A.A.; Dalidovich, S.V.; Krasulin, A.P., Heat capacity, enthalpy of fusion, and thermodynamic properties of urea, Zhur. Prikl. Khim. (Leningrad), 1986, 59, 1456-1459. [all data]

Parks, Huffman, et al., 1933
Parks, G.S.; Huffman, H.M.; Barmore, M., Thermal data on organic compounds. XI. The heat capacities, entropies and free energies of ten compounds containing oxygen or nitrogen. J. Am. Chem. Soc., 1933, 55, 2733-2740. [all data]

Gibson, Latimer, et al., 1920
Gibson, G.E.; Latimer, W.M.; Parks, G.S., Entropy changes at low temperatures. I. Formic acid and urea. A test of the third law of thermodynamics, J. Am. Chem. Soc., 1920, 42, 1533-1542. [all data]

Gambino and Bros, 1988
Gambino, M.; Bros, J.P., Capacite calorifique de l'uree et de quelques melanges eutectiques a base d'uree entre 30 et 140°C, Thermochim. Acta, 1988, 127, 223-236. [all data]

Sasaki and Yokotake, 1966
Sasaki, K.; Yokotake, T., Thermodynamic properties of the products in SO3-NH3 reaction. II. Specific heats of sulfamide and ammonium sulfamate, Tokyo Kogyo Shikenshi Hokohu, 1966, 61, 309-314. [all data]

Ruehrwein and Huffman, 1946
Ruehrwein, R.A.; Huffman, H.M., Thermal data. XIX. The heat capacity, entropy and free energy of urea, J. Am. Chem. Soc., 1946, 68, 1759-1761. [all data]

Campbell and Campbell, 1940
Campbell, A.N.; Campbell, A.J.R., The heats of solution, heats of formation, specific heats and equilibrium diagrams of certain molecular compounds. J. Am. Chem. Soc., 1940, 62, 291-297. [all data]

Ferloni and DellaGatta, 1995
Ferloni, P.; DellaGatta, G., Heat capacities of urea, N-methylurea, N-ethylurea, N-(n)propylurea, and N- (n)butylurea in the range 200 to 360 K, Thermochim. Acta, 1995, 266, 203-12. [all data]

Kabo, Miroshnichenko, et al., 1990, 2
Kabo, G.Ya.; Miroshnichenko, E.A.; Frenkel, M.L.; Kozyro, A.A.; Simirsky, V.V.; Krasulin, A.P.; Vorob'eva, V.P.; Lebedev, Yu.A., Thermochemistry of Alkyl Derivatives of Urea, Izv. Akad. Nauk SSSR, Ser. Khim., 1990, No. 4, 750-5. [all data]

Kozyro, Dalidovich, et al., 1986, 2
Kozyro, A.A.; Dalidovich, S.V.; Krausulin, A.P., Zh. Prikl. Khim. (S.-Peterburg), 1986, 59, 1456. [all data]

Vogel and Schuberth, 1980
Vogel, L.; Schuberth, H., Some physicochemical data of urea near the melting point<, Chem. Tech. (Leipzig), 1980, 32, 143. [all data]

Emel'yanenko, Kabo, et al., 2006
Emel'yanenko, Vladimir N.; Kabo, Gennady J.; Verevkin, Sergey P., Measurement and Prediction of Thermochemical Properties: Improved Increments for the Estimation of Enthalpies of Sublimation and Standard Enthalpies of Formation of Alkyl Derivatives of Urea, J. Chem. Eng. Data, 2006, 51, 1, 79-87, https://doi.org/10.1021/je050230z . [all data]

De Wit, Van Miltenburg, et al., 1983
De Wit, H.G.M.; Van Miltenburg, J.C.; De Kruif, C.G., Thermodynamic properties of molecular organic crystals containing nitrogen, oxygen, and sulphur 1. Vapour pressures and enthalpies of sublimation, The Journal of Chemical Thermodynamics, 1983, 15, 7, 651-663, https://doi.org/10.1016/0021-9614(83)90079-4 . [all data]

Suzuki, Onishi, et al., 1956
Suzuki, K.; Onishi, S.; Koide, T.; Seki, S., Vapor pressures of molecular crystals. XI. Vapor pressures of crystalline urea and diformylhydrazine. Energies of hydrogen bonds in these crystals, Bull. Chem. Soc. Jpn., 1956, 29, 127. [all data]

Zaitsau, Kabo, et al., 2003
Zaitsau, Dz; Kabo, G.J.; Kozyro, A.A.; Sevruk, V.M., The effect of the failure of isotropy of a gas in an effusion cell on the vapor pressure and enthalpy of sublimation for alkyl derivatives of carbamide, Thermochimica Acta, 2003, 406, 1-2, 17-28, https://doi.org/10.1016/S0040-6031(03)00231-4 . [all data]

Ferro, Barone, et al., 1987
Ferro, D.; Barone, G.; Della Gatta, G.; Piacente, V., Vapour pressures and sublimation enthalpies of urea and some of its derivatives, The Journal of Chemical Thermodynamics, 1987, 19, 9, 915-923, https://doi.org/10.1016/0021-9614(87)90038-3 . [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Trimble and Voorhoeve, 1978
Trimble, L.E.; Voorhoeve, R.J.H., Continuous colorimetric monitoring of vapour-phase urea and cyanates, Analyst, 1978, 103, 1228, 759, https://doi.org/10.1039/an9780300759 . [all data]

Suzuki, Onishi, et al., 1956, 2
Suzuki, Keisuke; Onishi, Shun-ichi; Koide, Tsutomu; Seki, Syuzo, Vapor Pressures of Molecular Crystals. XI. Vapor Pressures of Crystalline Urea and Diformylhydrazine. Energies of Hydrogen Bonds in these Crystals, Bull. Chem. Soc. Jpn., 1956, 29, 1, 127-131, https://doi.org/10.1246/bcsj.29.127 . [all data]

Jones, 1960
Jones, A.H., Sublimation Pressure Data for Organic Compounds., J. Chem. Eng. Data, 1960, 5, 2, 196-200, https://doi.org/10.1021/je60006a019 . [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press Inc., London, 1970, 643. [all data]

Bradley and Cleasby, 1953
Bradley, R.S.; Cleasby, T.G., 346. The vapour pressure and lattice energy of hydrogen-bonded crystals. Part I. Oxamide, oxamic acid, and rubeanic acid, J. Chem. Soc., 1953, 1681, https://doi.org/10.1039/jr9530001681 . [all data]

Della Gatta and Ferro, 1987
Della Gatta, G.; Ferro, D., Enthalpies of fusion and solid-to-solid transition, entropies of fusion for urea and twelve alkylureas, Thermochim. Acta, 1987, 122, 143-152. [all data]

Vogel and Schuberth, 1980, 2
Vogel, L.; Schuberth, H., Some physicochemical data of urea near the melting point, Chem. Tech. (Leipzig), 1980, 32, 143-144. [all data]

Rai and Rai, 1999
Rai, U.S.; Rai, R.N., Some Physicochemical Studies on Organic Eutectics and Molecular Complex: Urea -- p-nitrophenol System, J. Mater. Res., 1999, 14, 04, 1299-1305, https://doi.org/10.1557/JMR.1999.0177 . [all data]

Jamróz, Palczewska-Tulinska, et al., 1998
Jamróz, Malgorzata E.; Palczewska-Tulinska, Marcela; Wyrzykowska-Stankiewicz, Danuta; Szafranski, Andrzej M.; Polaczek, Jerzy; Dobrowolski, Jan Cz.; Jamróz, Michal H.; Mazurek, Aleksander P., The urea--phenol(s) systems, Fluid Phase Equilibria, 1998, 152, 2, 307-326, https://doi.org/10.1016/S0378-3812(98)90206-0 . [all data]

Rai and Rai, 1998
Rai, U.S.; Rai, R.N., Journal of Thermal Analysis and Calorimetry, 1998, 53, 3, 883-893, https://doi.org/10.1023/A:1010190402954 . [all data]

Ferloni and Gatta, 1995
Ferloni, Paolo; Gatta, Giuseppe Della, Heat capacities of urea, N-methylurea, N-ethylurea, N-(n)propylurea, and N-(n)butylurea in the range 200 to 360 K, Thermochimica Acta, 1995, 266, 203-212, https://doi.org/10.1016/0040-6031(95)02453-0 . [all data]

Ma, Wang, et al., 1998
Ma, S.G.; Wang, F.; Cooks, R.G., Gas-phase acidity of urea, J. Mass Spectrom., 1998, 33, 10, 943-949, https://doi.org/10.1002/(SICI)1096-9888(1998100)33:10<943::AID-JMS703>3.0.CO;2-B . [all data]

Taft, 1987
Taft, R.W., The Nature and Analysis of Substitutent Electronic Effects, Personal communication. See also Prog. Phys. Org. Chem., 1987, 16, 1. [all data]

Muftakhov, Vasil'ev, et al., 1999
Muftakhov, M.V.; Vasil'ev, Y.V.; Mazunov, V.A., Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry, Rapid Commun. Mass Spectrom., 1999, 13, 12, 1104-1108, https://doi.org/10.1002/(SICI)1097-0231(19990630)13:12<1104::AID-RCM619>3.0.CO;2-C . [all data]

Lopatin, Popov, et al., 1992
Lopatin, E.B.; Popov, V.V.; Epshtein, N.A.; Mikhaleva, L.M.; Makarov, Yu.N., Kinetic and thermochemical characteristics of diketene-based reactions, Khim.-Farm. Zh., 1992, 26, 76-78. [all data]

Rukevich and Zagranichnyi, 1971
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Notes

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