Acetophenone
- Formula: C8H8O
- Molecular weight: 120.1485
- IUPAC Standard InChIKey: KWOLFJPFCHCOCG-UHFFFAOYSA-N
- CAS Registry Number: 98-86-2
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript. - Isotopologues:
- Other names: Ethanone, 1-phenyl-; Acetophenon; Benzoyl methide; Hypnon; Hypnone; Methyl phenyl ketone; Phenyl methyl ketone; 1-Phenylethanone; Acetylbenzene; 1-Phenyl-1-ethanone; Ketone, methyl phenyl-; USAF EK-496; Acetofenon; Benzene, acetyl-; Dymex; Rcra waste number U004; Acetylbenzol; NSC 7635; Phenylethanone; 1-phenylethanone (acetophenone)
- Permanent link for this species. Use this link for bookmarking this species for future reference.
- Information on this page:
- Other data available:
- Data at other public NIST sites:
- Options:
Data at NIST subscription sites:
NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.
Condensed phase thermochemistry data
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, 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 |
---|---|---|---|---|---|
ΔfH°liquid | -34.07 ± 0.25 | kcal/mol | Ccb | Colomina, Latorre, et al., 1961 | Reanalyzed by Cox and Pilcher, 1970, Original value = -34.06 ± 0.25 kcal/mol; ALS |
Quantity | Value | Units | Method | Reference | Comment |
ΔcH°liquid | -989.6 | kcal/mol | Ccb | Seno, Tsuchiya, et al., 1975 | Corresponding ΔfHºliquid = -36.1 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
ΔcH°liquid | -991.62 ± 0.21 | kcal/mol | Ccb | Colomina, Latorre, et al., 1961 | Corresponding ΔfHºliquid = -34.05 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
ΔcH°liquid | -988.5 | kcal/mol | Ccb | Guinchant, 1918 | Corresponding ΔfHºliquid = -37.2 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
Constant pressure heat capacity of liquid
Cp,liquid (cal/mol*K) | Temperature (K) | Reference | Comment |
---|---|---|---|
54.40 | 303.2 | Phillip, 1939 | DH |
Reaction thermochemistry data
Go To: Top, Condensed phase thermochemistry data, Gas phase ion energetics data, 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
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
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
By formula: Br- + C8H8O = (Br- • C8H8O)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 14.1 ± 1.8 | kcal/mol | IMRE | Paul and Kebarle, 1991 | gas phase; ΔGaff measured at 303 K, corrected to 423 K, ΔSaff taken as that of PhNO2..Br-; B,M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 20. | cal/mol*K | N/A | Paul and Kebarle, 1991 | gas phase; Entropy change calculated or estimated; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 5.6 ± 1.0 | kcal/mol | IMRE | Paul and Kebarle, 1991 | gas phase; ΔGaff measured at 303 K, corrected to 423 K, ΔSaff taken as that of PhNO2..Br-; B |
Free energy of reaction
ΔrG° (kcal/mol) | T (K) | Method | Reference | Comment |
---|---|---|---|---|
5.6 | 423. | PHPMS | Paul and Kebarle, 1991 | gas phase; Entropy change calculated or estimated; M |
C8H7O- + =
By formula: C8H7O- + H+ = C8H8O
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 361.3 ± 2.1 | kcal/mol | G+TS | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrH° | 362.0 ± 2.7 | kcal/mol | D-EA | Zimmerman, Reed, et al., 1977 | gas phase; B |
ΔrH° | 362.3 ± 2.6 | kcal/mol | G+TS | Cumming and Kebarle, 1978 | gas phase; B |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 354.5 ± 2.0 | kcal/mol | IMRE | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrG° | 355.5 ± 2.0 | kcal/mol | IMRE | Cumming and Kebarle, 1978 | gas phase; B |
By formula: C8H9O + C8H8O = (C8H9O • C8H8O)
Bond type: Hydrogen bonds of the type OH-O between organics
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 26.8 | kcal/mol | PHPMS | Meot-Ner (Mautner) and Sieck, 1991 | gas phase; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 27.2 | cal/mol*K | PHPMS | Meot-Ner (Mautner) and Sieck, 1991 | gas phase; M |
By formula: Cl- + C8H8O = (Cl- • C8H8O)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrG° | 9.50 | kcal/mol | TDEq | French, Ikuta, et al., 1982 | gas phase; B |
Free energy of reaction
ΔrG° (kcal/mol) | T (K) | Method | Reference | Comment |
---|---|---|---|---|
7.1 | 421. | PHPMS | French, Ikuta, et al., 1982 | gas phase; M |
By formula: C7H6O + C8H8O = H2O + C15H12O
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | -15.54 ± 0.45 | kcal/mol | Cm | Hao, Chang, et al., 1985 | liquid phase; solvent: Aqueous NaOH; ALS |
Gas phase ion energetics data
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias
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
View reactions leading to C8H8O+ (ion structure unspecified)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
IE (evaluated) | 9.28 ± 0.03 | eV | N/A | N/A | L |
Quantity | Value | Units | Method | Reference | Comment |
Proton affinity (review) | 205.8 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Quantity | Value | Units | Method | Reference | Comment |
Gas basicity | 198.2 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Electron affinity determinations
EA (eV) | Method | Reference | Comment |
---|---|---|---|
0.3339 ± 0.0043 | ECD | Wentworth, Kao, et al., 1975 | B |
0.3340 ± 0.0040 | ECD | Wentworth and Chen, 1967 | B |
2.550 ± 0.030 | LPES | Yagi, Maeyama, et al., 2007 | This vertical detachment energy value seems at least 2 eV too large. - JEB; B |
Proton affinity at 298K
Proton affinity (kcal/mol) | Reference | Comment |
---|---|---|
206.4 ± 0.1 | Tabrizchi and Shooshtari, 2003 | T = 413-467K; Authors report only relative PAs. Absolute values are referenced here to PA(CH3COOC2H5) = 835.7 kJ/mol as listed in Hunter and Lias, 1998, although average PA(CH3COOC2H5) from the literature sources in Hunter and Lias, 1998 is 831.0 kJ/mol; MM |
Ionization energy determinations
IE (eV) | Method | Reference | Comment |
---|---|---|---|
9.1 ± 0.1 | EI | Dallinga, Nibbering, et al., 1981 | LLK |
9.28 | PI | McLoughlin and Traeger, 1979 | LLK |
9.45 | EI | Elder, Beynon, et al., 1976 | LLK |
9.1 ± 0.1 | PE | Egdell, Green, et al., 1975 | LLK |
9.1 | EI | McLafferty, Bente, et al., 1973 | LLK |
9.50 | EI | Benoit, 1973 | LLK |
9.3 ± 0.2 | PI | Iskakov and Potapov, 1971 | LLK |
9.15 ± 0.03 | EI | Bock, Alt, et al., 1969 | RDSH |
9.27 ± 0.03 | PI | Watanabe, Nakayama, et al., 1962 | RDSH |
9.6 | PI | Terenin, 1961 | RDSH |
9.38 | PE | Distefano, Granozzi, et al., 1987 | Vertical value; LBLHLM |
9.51 | PE | Gal, Geribaldi, et al., 1985 | Vertical value; LBLHLM |
9.51 | PE | Pfister-Guillouzo, Geribaldi, et al., 1982 | Vertical value; LBLHLM |
9.45 | PE | Centineo, Fragala, et al., 1978 | Vertical value; LLK |
9.45 | PE | Koenig, Wielesek, et al., 1977 | Vertical value; LLK |
9.35 | PE | Benoit and Harrison, 1977 | Vertical value; LLK |
8.9 | PE | Rao, 1975 | Vertical value; LLK |
9.37 | PE | Kobayashi and Nagakura, 1974 | Vertical value; LLK |
Appearance energy determinations
Ion | AE (eV) | Other Products | Method | Reference | Comment |
---|---|---|---|---|---|
C2H3O+ | 11.40 ± 0.28 | ? | EI | Foffani, Pignataro, et al., 1963 | RDSH |
C6H5+ | 13.97 | CO+CH3 | EI | Benoit, 1973 | LLK |
C6H5+ | 13.28 | CO+CH3 | EI | Johnstone and Mellon, 1972 | LLK |
C6H5+ | 13.42 ± 0.07 | ? | EI | Foffani, Pignataro, et al., 1963 | RDSH |
C7H5O+ | 9.67 | CH3 | PI | McLoughlin and Traeger, 1979 | LLK |
C7H5O+ | 10.50 ± 0.01 | CH3 | EI | Helal and Zahran, 1978 | LLK |
C7H5O+ | 10.08 | CH3 | EI | Elder, Beynon, et al., 1976 | LLK |
C7H5O+ | 9.6 | CH3 | EI | McLafferty, Bente, et al., 1973 | LLK |
C7H5O+ | 10.38 | CH3 | EI | Benoit, 1973 | LLK |
C7H5O+ | 9.91 | CH3 | EI | Buchs, Rossetti, et al., 1964 | RDSH |
De-protonation reactions
C8H7O- + =
By formula: C8H7O- + H+ = C8H8O
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 361.3 ± 2.1 | kcal/mol | G+TS | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrH° | 362.0 ± 2.7 | kcal/mol | D-EA | Zimmerman, Reed, et al., 1977 | gas phase; B |
ΔrH° | 362.3 ± 2.6 | kcal/mol | G+TS | Cumming and Kebarle, 1978 | gas phase; B |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 354.5 ± 2.0 | kcal/mol | IMRE | Bartmess, Scott, et al., 1979 | gas phase; value altered from reference due to change in acidity scale; B |
ΔrG° | 355.5 ± 2.0 | kcal/mol | IMRE | Cumming and Kebarle, 1978 | gas phase; B |
References
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Colomina, Latorre, et al., 1961
Colomina, M.; Latorre, C.; Perez-Ossorio, R.,
Heats of combustion of five alkyl phenyl ketones,
Pure & Appl. Chem., 1961, 2, 133-135. [all data]
Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G.,
Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]
Seno, Tsuchiya, et al., 1975
Seno, M.; Tsuchiya, S.; Kise, H.; Asahara, T.,
Studies on bond character in phosphorus ylides by combustion heat and x-ray photoelectron spectroscopy,
Bull. Chem. Soc. Jpn., 1975, 48, 2001-2005. [all data]
Guinchant, 1918
Guinchant, M.J.,
Etude sur la fonction acide dans les derives metheniques et methiniques,
Ann. Chem., 1918, 10, 30-84. [all data]
Phillip, 1939
Phillip, N.M.,
Adiabatic and isothermal compressibilities of liquids,
Proc. Indian Acad. Sci., 1939, A9, 109-120. [all data]
Paul and Kebarle, 1991
Paul, G.J.C.; Kebarle, P.,
Stabilities of Complexes of Br- with Substituted Benzenes (SB) Based on Determinations of the Gas-Phase Equilibria Br- + SB = (BrSB)-,
J. Am. Chem. Soc., 1991, 113, 4, 1148, https://doi.org/10.1021/ja00004a014
. [all data]
Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr.,
The gas phase acidity scale from methanol to phenol,
J. Am. Chem. Soc., 1979, 101, 6047. [all data]
Zimmerman, Reed, et al., 1977
Zimmerman, A.H.; Reed, K.J.; Brauman, J.I.,
Photodetachment of electrons from enolate anions. Gas phase electron affinities of enolate radicals,
J. Am. Chem. Soc., 1977, 99, 7203. [all data]
Cumming and Kebarle, 1978
Cumming, J.B.; Kebarle, P.,
Summary of gas phase measurements involving acids AH. Entropy changes in proton transfer reactions involving negative ions. Bond dissociation energies D(A-H) and electron affinities EA(A),
Can. J. Chem., 1978, 56, 1. [all data]
Meot-Ner (Mautner) and Sieck, 1991
Meot-Ner (Mautner), M.; Sieck, L.W.,
Proton affinity ladders from variable-temperature equilibrium measurements. 1. A reevaluation of the upper proton affinity range,
J. Am. Chem. Soc., 1991, 113, 12, 4448, https://doi.org/10.1021/ja00012a012
. [all data]
French, Ikuta, et al., 1982
French, M.A.; Ikuta, S.; Kebarle, P.,
Hydrogen bonding of O-H and C-H hydrogen donors to Cl-. Results from mass spectrometric measurement of the ion-molecule equilibria RH + Cl- = RHCl-,
Can. J. Chem., 1982, 60, 1907. [all data]
Hao, Chang, et al., 1985
Hao, J.; Chang, J.; Wang, K.; Liu, Y.; Zhong, G.,
Heat of reaction of chalcone by calorimetric measurement,
Huaxue Tongbao, 1985, 15-16. [all data]
Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G.,
Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update,
J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018
. [all data]
Wentworth, Kao, et al., 1975
Wentworth, W.E.; Kao, L.W.; Becker, R.S.,
Electron affinities of substituted aromatic compounds,
J. Phys. Chem., 1975, 79, 1161. [all data]
Wentworth and Chen, 1967
Wentworth, W.E.; Chen, E.,
Experimental Determination of the Electron Affinity of Several Aromatic Aldehydes and Ketones,
J. Phys. Chem., 1967, 71, 6, 1929, https://doi.org/10.1021/j100865a063
. [all data]
Yagi, Maeyama, et al., 2007
Yagi, I.; Maeyama, T.; Fujii, A.; Mikami, N.,
Stepwise solvatochromism of ketyl anions in the gas phase: Photodetachment excitation spectroscopy of benzophenone and acetophenone radical anions microsolvated with methanol,
J. Phys. Chem. A, 2007, 111, 31, 7646-7652, https://doi.org/10.1021/jp072167l
. [all data]
Tabrizchi and Shooshtari, 2003
Tabrizchi, M.; Shooshtari, S.,
Proton affinity measurements using ion mobility spectrometry,
J. Chem. Thermodynamics, 2003, 35, 863. [all data]
Dallinga, Nibbering, et al., 1981
Dallinga, J.W.; Nibbering, N.M.M.; Louter, G.J.,
Formation and structure of [C8H8O]+ ions, generated from gas phase ions of phenylcyclopropylcarbinol and 1-phenyl-1-(hydroxymethyl)cyclopropane,
Org. Mass Spectrom., 1981, 16, 4. [all data]
McLoughlin and Traeger, 1979
McLoughlin, R.G.; Traeger, J.C.,
A photoionization study of some benzoyl compounds - thermochemistry of [C7H5O]+ formation,
Org. Mass Spectrom., 1979, 14, 434. [all data]
Elder, Beynon, et al., 1976
Elder, J.F.; Beynon, J.H.; Cooks, R.G.,
The benzoyl ion. Thermochemistry and kinetic energy release,
Org. Mass Spectrom., 1976, 11, 415. [all data]
Egdell, Green, et al., 1975
Egdell, R.; Green, J.C.; Rao, C.N.R.,
Photoelectron spectra of substituted benzenes,
Chem. Phys. Lett., 1975, 33, 600. [all data]
McLafferty, Bente, et al., 1973
McLafferty, F.W.; Bente, P.F., III; Kornfeld, R.; Tsai, S.-C.; Howe, I.,
Collisional activation spectra of organic ions,
J. Am. Chem. Soc., 1973, 95, 2120. [all data]
Benoit, 1973
Benoit, F.,
The benzoyl cation: The participation of isolated electronic excited states in the dissociation of molecular ions of the form [C6H5COX]+,
Org. Mass Spectrom., 1973, 7, 1407. [all data]
Iskakov and Potapov, 1971
Iskakov, L.I.; Potapov, V.K.,
Photionization and decomposition of benzaldehyde, acetophenone, and benzophenone,
High Energy Chem., 1971, 5, 238, In original 265. [all data]
Bock, Alt, et al., 1969
Bock, H.; Alt, H.; Seidl, H.,
d-Orbital effects in silicon-substituted π-electron systems. XV. The color of silyl ketones,
J. Am. Chem. Soc., 1969, 91, 355. [all data]
Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J.,
Ionization potentials of some molecules,
J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]
Terenin, 1961
Terenin, A.,
Charge transfer in organic solids, induced by light,
Proc. Chem. Soc., London, 1961, 321. [all data]
Distefano, Granozzi, et al., 1987
Distefano, G.; Granozzi, G.; Olivato, P.R.; Guerrero, S.A.,
Hyperconjugative interactions in halogen-substituted carbonyls: Ultraviolet photoelectron spectroscopy of w-halogenoacetophenones,
J. Chem. Soc. Perkin Trans. 2, 1987, 1459. [all data]
Gal, Geribaldi, et al., 1985
Gal, J.-F.; Geribaldi, S.; Pfister-Guillouzo, G.; Morris, D.G.,
Basicity of the carbonyl group. Part 12. Correlations between ionization potentials and lewis basicities in aromatic carbonyl compounds,
J. Chem. Soc. Perkin Trans. 2, 1985, 103. [all data]
Pfister-Guillouzo, Geribaldi, et al., 1982
Pfister-Guillouzo, G.; Geribaldi, S.; Gal, J.-F.,
Spectres photoelectroniques de cyclohexene-2-ones-1 diversement substituees en position 3. Correlations avec la reactivite,
Can. J. Chem., 1982, 60, 1163. [all data]
Centineo, Fragala, et al., 1978
Centineo, G.; Fragala, I.; Bruno, G.; Spampinato, S.,
Photoelectron spectroscopy of benzophenone, acetophenone and their ortho-alkyl derivatives,
J. Mol. Struct., 1978, 44, 203. [all data]
Koenig, Wielesek, et al., 1977
Koenig, T.; Wielesek, R.; Miller, L.L.; So, Y.-H.,
Correlation of electrochemical reactivity and photoelectron spectra of aromatic ketones,
J. Am. Chem. Soc., 1977, 99, 7061. [all data]
Benoit and Harrison, 1977
Benoit, F.M.; Harrison, A.G.,
Predictive value of proton affinity. Ionization energy correlations involving oxygenated molecules,
J. Am. Chem. Soc., 1977, 99, 3980. [all data]
Rao, 1975
Rao, C.N.R.,
Lone-pair ionization bands of chromophores in the photoelectron spectra of organic molecules,
Indian J. Chem., 1975, 13, 950. [all data]
Kobayashi and Nagakura, 1974
Kobayashi, T.; Nagakura, S.,
Photoelectron spectra of substituted benzenes,
Bull. Chem. Soc. Jpn., 1974, 47, 2563. [all data]
Foffani, Pignataro, et al., 1963
Foffani, A.; Pignataro, S.; Cantone, B.; Grasso, F.,
Mass spectra of diazocompounds. I. Diazocarbonyl compounds,
Nuovo Cimento, 1963, 29, 918. [all data]
Johnstone and Mellon, 1972
Johnstone, R.A.W.; Mellon, F.A.,
Electron-impact ionization and appearance potentials,
J. Chem. Soc. Faraday Trans. 2, 1972, 68, 1209. [all data]
Helal and Zahran, 1978
Helal, A.I.; Zahran, N.F.,
Kinetic shift in some para-substituted acetophenones,
Org. Mass Spectrom., 1978, 13, 549. [all data]
Buchs, Rossetti, et al., 1964
Buchs, A.; Rossetti, G.P.; Susz, B.P.,
Etude, en fonction de la constante σp de Hammett, du spectre de masse d'acetophenones p-substituees,
Helv. Chim. Acta, 1964, 47, 1563. [all data]
Notes
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, References
- Symbols used in this document:
AE Appearance energy Cp,liquid Constant pressure heat capacity of liquid EA Electron affinity IE (evaluated) Recommended ionization energy T Temperature ΔcH°liquid Enthalpy of combustion of liquid at standard conditions ΔfH°liquid Enthalpy of formation of liquid at standard conditions ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions ΔrS° Entropy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
- The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
- Customer support for NIST Standard Reference Data products.