Archive for August, 2008

Sodium metavanadate

Sunday, August 31st, 2008

Sodium vanadate

Image:Sodium vanadate.jpg

IUPAC name
Sodium trioxovanadate(V)

Other names
Sodium vanadate

Identifiers

CAS number

Properties

Molecular formula
NaVO3

Molar mass
121.92897 g/mol

Appearance
Yellow crystalline solid

Density
 ? g/cm3, ?

Melting point

630°C (? K)

Boiling point

(? K)

Solubility in water
<0.1 g/100 ml (20°C)

Hazards

Main hazards
toxic, oxidizing, irritant

Related compounds

Other anions
NaNO3, NaBiO3

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

Sodium metavanadate is a yellow solid which is soluble in water. Its use is limited due to its hygroscopic property. Its natural forms include mineral metamunirite (anhydrous) and a dihydrate, munirite. Both are very rare, metamunirite is now known only from V- and U-bearing sandstone formations of central-western USA and munirite from Pakistan and South Africa.

See also

  • Sodium orthovanadate

References

  1. ^ http://www.mindat.org/min-2680.html and http://www.mindat.org/min-2680.html Mindat


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Retrieved from “http://en.wikipedia.org/wiki/Sodium_metavanadate
Categories: Vanadates | Sodium compounds | Inorganic compounds | Inorganic compound stubs

Mineral acid

Sunday, August 31st, 2008

Acids and bases:

  • Acid dissociation constant
  • Acid-base extraction
  • Acid-base reaction
  • Acid-base physiology
  • Acid-base homeostasis
  • Dissociation constant
  • Acidity function
  • Buffer solutions
  • pH
  • Proton affinity
  • Self-ionization of water
  • Acids:
    • Lewis acids
    • Mineral acids
    • Organic acids
    • Strong acids
    • Superacids
    • Weak acids
  • Bases:
    • Lewis bases
    • Organic bases
    • Strong bases
    • Superbases
    • Non-nucleophilic bases
    • Weak bases

edit

A mineral acid is an acid derived by chemical reaction from inorganic minerals, as opposed to organic acids. These have hydrogen(s) atoms covalently bonded with an anion, such as sulfate, or chloride, depending on the charge of the anion.

Characteristics

Mineral acids range from acids of great strength (example: sulfuric acid) to very weak (boric acid). As mineral acid molecules tend to consist of only a few atoms, of which many are polar, they tend to be very soluble in water, and insoluble in organic solvents. Mineral acids are very important to chemical procedures.

These acids are most often used in large-scale industries. For example, a dilute solution of hydrochloric acid is used for removing the deposits from the inside of boilers, with precautions taken to prevent the corrosion of the boiler by the acid. This process is known as de-scaling. Therefore, large quantities of these acids, especially sulfuric acid, nitric acid and hydrochloric acid are manufactured for commercial use in large plants.

Examples

  • Hydrochloric acid
  • Nitric acid
  • Phosphoric acid
  • Sulfuric acid
  • Boric acid
  • Hydrofluoric acid


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Categories: Acids | Inorganic compound stubs

Peroxydisulfuric acid

Sunday, August 31st, 2008

Peroxydisulfuric acid

IUPAC name
μ-peroxido-bis(hydroxidodioxidosulfur)
peroxydisulfuric acid

Other names
persulfuric acid

Identifiers

CAS number

PubChem
24413

ChEBI
29268

SMILES

 

OS(=O)(=O)OOS(=O)(=O)O

InChI

 

1/H2O8S2/c1-9(2,3)7-8-10(4,5)6/h(H,1,2,3)(H,4,5,6)/f/h1,4H

Properties

Molecular formula
H2O8S2

Molar mass
194.14 g mol-1

Appearance
colourless solid

Melting point

65 °C, 338 K, 149 °F (decomposes)

Related compounds

Related compounds
Dipotassium persulfate

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

Peroxydisulfuric is a sulfur oxoacid with the chemical formula H2S2O8. In structural terms it can be written HO3SOOSO3H. It is one of a group of sulfur oxoacids, its salts, commonly known as persulfates, are industrially important but the acid itself is not. The salts contain the peroxydisulfate ion.

See also

  • Sulfur oxoacids

References

The references used in this article may be clearer with a different or consistent style of citation, footnoting, or external linking.

Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4


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Categories: Sulfur oxoacids | Acids | Persulfates | Peroxy acids | Sulfur compounds | Inorganic compound stubsHidden category: Wikipedia references cleanup

Aluminium oxide (data page)

Sunday, August 31st, 2008

This page provides supplementary chemical data on aluminium oxide.

Contents

//

Material Safety Data Sheet

  • MSDS from SIRI

Structure and properties

Structure and properties

Dielectric constant, ε11=ε22
9.34 ε0 at 25 °C

Dielectric constant, ε33
11.54 ε0 at 25 °C

Bond strength
 ?

Bond length
 ?

Bond angle
 ?

Magnetic susceptibility
 ?

Table of Refractive index

Wavelength(µm)
no
ne

0.193
1.92879
1.91743

0.213
1.88903
1.87839

0.222
1.8754
1.86504

0.226
1.87017
1.85991

0.244
1.85059
1.84075

0.248
1.84696
1.83719

0.257
1.83932
1.82972

0.266
1.83304
1.82358

0.280
1.82437
1.81509

0.308
1.81096
1.80198

0.325
1.80467
1.79582

0.337
1.80082
1.79206

0.351
1.79693
1.78825

0.355
1.79598
1.78732

0.442
1.78038
1.77206

0.458
1.77843
1.77015

0.488
1.7753
1.76711

0.515
1.77304
1.76486

0.532
1.7717
1.76355

0.590
1.76804
1.75996

0.633
1.7659
1.75787

0.670
1.76433
1.75632

0.694
1.76341
1.75542

0.755
1.76141
1.75346

0.780
1.76068
1.75274

0.800
1.76013
1.7522

0.820
1.75961
1.75168

0.980
1.75607
1.74819

1.064
1.75449
1.74663

1.320
1.75009
1.74227

1.550
1.74618
1.73838

2.010
1.73748
1.72973

2.24929
1.73232
1.72432

2.703
1.719
1.711

2.941
1.712
1.704

3.333
1.701
1.693

3.704
1.687
1.679

4.000
1.674
1.666

4.348
1.658
1.65

4.762
1.636
1.628

5.000
1.623
1.615

5.263
1.607
1.599

Table of Coefficients of Sellmeier equation

Coefficient
for ordinary wave
for extraordinary wave

B1
1.43134930
1.5039759

B2
6.5054713×10-1
5.5069141×10-1

B3
5.3414021
6.5937379

C1
5.2799261-3µm2
5.48041129-3µm2

C2
1.42382647-2µm2
1.47994281-2µm2

C3
3.250178342µm2
4.02895142µm2

Thermodynamic properties

Phase behavior

Triple point
 ? K (? °C), ? Pa

Critical point
 ? K (? °C), ? Pa

Std enthalpy change
of fusion
, ΔfusHo
 ? kJ/mol

Std entropy change
of fusion
, ΔfusSo
 ? J/(mol·K)

Std enthalpy change
of vaporization
, ΔvapHo
 ? kJ/mol

Std entropy change
of vaporization
, ΔvapSo
 ? J/(mol·K)

Solid properties

Std enthalpy change
of formation
, ΔfHosolid
-1675.7 kJ/mol

Standard molar entropy,
Sosolid
50.92 J/(mol K)

Heat capacity, cp
79.04 J/(mol K)

Liquid properties

Std enthalpy change
of formation
, ΔfHoliquid
-1620.57 kJ/mol

Standard molar entropy,
Soliquid
67.24 J/(mol K)

Heat capacity, cp
192.5 J/(mol K)

Gas properties

Std enthalpy change
of formation
, ΔfHogas
 ? kJ/mol

Standard molar entropy,
Sogas
 ? J/(mol K)

Heat capacity, cp
 ? J/(mol K)

Spectral data

UV-Vis

λmax
 ? nm

Extinction coefficient, ε
 ?

IR

Major absorption bands
 ? cm−1

NMR

Proton NMR
 

Carbon-13 NMR
 

Other NMR data
 

MS

Masses of
main fragments
 

References

Except where noted otherwise, data relate to standard ambient temperature and pressure.

Disclaimer applies.

Retrieved from “http://en.wikipedia.org/wiki/Aluminium_oxide_(data_page)
Categories: Chemical data pages

Benzene (data page)

Sunday, August 31st, 2008

This page provides supplementary chemical data on benzene.

Contents

//

Material Safety Data Sheet

The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source such as SIRI, and follow its directions. MSDS for benzene available at AMOCO.

Structure and properties

Structure and properties

Index of refraction, nD
1.5011 at 20°C

Abbe number
?

Dielectric constant, εr
(2.274 – 0.0020ΔT) ε0
T = T – 25 °C)

Bond strength
 ?

Bond length
 ?

Bond angle
120° C–C–C
120° H–C–C

Magnetic susceptibility
 ?

Surface tension
28.88 dyn/cm at 25°C

Viscosity

0.7528 mPa·s
at 10°C

0.6999 mPa·s
at 15°C

0.6516 mPa·s
at 20°C

0.6076 mPa·s
at 25°C

0.5673 mPa·s
at 35°C

0.4965 mPa·s
at 40°C

0.4655 mPa·s
at 45°C

0.4370 mPa·s
at 50°C

0.4108 mPa·s
at 55°C

0.3867 mPa·s
at 60°C

0.3644 mPa·s
at 65°C

0.3439 mPa·s
at 70°C

0.3250 mPa·s
at 75°C

0.3075 mPa·s
at 80°C

Thermodynamic properties

Phase behavior

Triple point
278.5 K (5.4 °C), ? Pa

Critical point
562 K (289 °C), 4.74 MPa

Std enthalpy change
of fusion
, ΔfusHo
9.9 kJ/mol at 5.42 °C

Std entropy change
of fusion
, ΔfusSo
35.5 J/(mol·K) at 5.42 °C

Std enthalpy change
of vaporization
, ΔvapHo
33.9 kJ/mol at 25°C
30.77 kJ/mol at 80.1°C

Std entropy change
of vaporization
, ΔvapSo
113.6 J/(mol·K) at 25°C
87.1 J/(mol·K) at 80.1°C

Solid properties

Std enthalpy change
of formation
, ΔfHosolid
 ? kJ/mol

Standard molar entropy,
Sosolid
45.56 J/(mol K)

Heat capacity, cp
118.4 J/(mol K) at 0°C

Liquid properties

Std enthalpy change
of formation
, ΔfHoliquid
+48.7 kJ/mol

Standard molar entropy,
Soliquid
173.26 J/(mol K)

Enthalpy of combustion, ΔcHo
–3273 kJ/mol

Heat capacity, cp
134.8 J/(mol K)

Gas properties

Std enthalpy change
of formation
, ΔfHogas
+82.93 kJ/mol

Standard molar entropy,
Sogas
234.9 J/(mol K)

Heat capacity, cp
82.44 J/(mol K) at 25°C

van der Waals’ constants
a = 1823.9 L2 kPa/mol2
b = 0.1154 liter per mole

Vapor pressure of liquid

P in mm Hg
1
10
40
100
400
760
1520
3800
7600
15200
30400
45600

T in °C
–36.7(s)
–11.5(s)
7.6
26.1
60.6
80.1
103.8
142.5
178.8
221.5
272.3
 —

Table data obtained from CRC Handbook of Chemistry and Physics 44th ed. Note: (s) notation indicates equilibrium temperature of vapor over solid, otherwise value is equilibrium temperature of vapor over liquid.


log of Benzene vapor pressure. Uses formula: obtained from CHERIC Note: yellow area is the region where the formula disagrees with tabulated data above.

Distillation data

Vapor-liquid Equilibrium
for Benzene/Ethanol
P = 760 mm Hg

BP
Temp.
°C
 % by mole ethanol

liquid
vapor

70.8
8.6
26.5

69.8
11.2
28.2

69.6
12.0
30.8

69.1
15.8
33.5

68.5
20.0
36.8

67.7
30.8
41.0

67.7
44.2
44.6

68.1
60.4
50.5

69.6
77.0
59.0

70.4
81.5
62.8

70.9
84.1
66.5

72.7
89.8
74.4

73.8
92.4
78.2

   

Vapor-liquid Equilibrium
for Benzene/Methanol
P = 760 mm Hg

BP
Temp.
°C
 % by mole methanol

liquid
vapor

70.67
2.6
26.7

66.44
5.0
37.1

62.87
8.8
45.7

60.20
16.4
52.6

58.64
33.3
55.9

58.02
54.9
59.5

58.10
69.9
63.3

58.47
78.2
66.5

59.90
89.8
76.0

62.71
97.3
90.7

   

Vapor-liquid Equilibrium
for Benzene/Acetone
P = 101.325 kPa

BP
Temp.
°C
 % by mole benzene

liquid
vapor

57.34
11.7
7.4

57.48
12.8
8.1

57.75
15.1
9.5

59.21
26.7
16.6

59.24
27.0
16.7

60.01
32.7
20.2

60.71
37.3
23.1

61.05
39.8
24.7

61.91
45.0
27.9

62.82
50.2
31.7

63.39
53.4
33.9

63.79
55.4
35.3

64.22
57.2
37.0

64.99
61.3
39.9

67.88
73.0
51.2

70.21
80.7
60.1

72.23
86.1
67.9

   

Vapor-liquid Equilibrium
for Benzene/n-Hexane
P = 760 mmHg

BP
Temp.
°C
 % by mole hexane

liquid
vapor

77.6
7.3
14.0

75.1
17.2
26.8

73.4
26.8
37.6

72.0
37.2
46.0

70.9
46.2
54.0

70.0
58.5
64.4

69.4
69.2
72.5

69.1
79.2
80.7

69.0
82.8
83.8

68.9
88.3
88.8

68.8
94.7
95.0

68.8
96.2
96.4

Spectral data

UV-Vis

λmax
 ? nm

Extinction coefficient, ε
 ?

IR

Major absorption bands

(liquid film)

Wave number
transmittance

3091 cm−1
42%

3072 cm−1
49%

3036 cm−1
27%

1961 cm−1
77%

1815 cm−1
70%

1526 cm−1
81%

1479 cm−1
20%

1393 cm−1
84%

1176 cm−1
86%

1038 cm−1
49%

674 cm−1
4%

NMR

Proton NMR
 

Carbon-13 NMR
 

Other NMR data
 

MS

Masses of
main fragments
 

Safety data

Material Safety Data Sheet for benzene:

Common synonyms
None

Physical properties
Form: colorless liquid

Stability: Stable, but very flammable

Melting point: 5.5 C

Water solubility: negligible

Specific gravity: 0.87

Principal hazards
*** Benzene is a carcinogen (cancer-causing agent).

*** Very flammable. The pure material, and any solutions containing it, constitute a fire risk.

Safe handling
Benzene should NOT be used at all unless no safer alternatives are available.

If benzene must be used in an experiment, it should be handled at all stages in a fume cupboard.

Wear safety glasses and use protective gloves.

Emergency
Eye contact: Immediately flush the eye with plenty of water. Continue for at least ten minutes

and call for immediate medical help.

Skin contact: Wash off with soap and water. Remove any contaminated clothing. If the skin

reddens or appears damaged, call for medical aid.

If swallowed: Call for immediate medical help.

Disposal
It is dangerous to try to dispose of benzene by washing it down a sink, since it is toxic, will cause environmental damage

and presents a fire risk. It is probable that trying to dispose of benzene in this way will also break local

environmental rules. Instead, retain in a safe place in the laboratory (well away from any source of ignition)

for disposal with other flammable, non-chlorinated solvents.

Protective equipment
Safety glasses. If gloves are worn, PVA, butyl rubber and viton are suitable materials.

References

  1. ^ a b c d “Pure Component Properties” (Queriable database). Chemical Engineering Research Information Center. Retrieved on 12-May 2007.
  2. ^ Lange’s Handbook of Chemistry 10th ed, pp 1522-1524
  3. ^ a b c d “Binary Vapor-Liquid Equilibrium Data” (Queriable database). Chemical Engineering Research Information Center. Retrieved on 12 May 2007.
  4. ^ “” (Queriable database). Advanced Industrial Science and Technology. Retrieved on 10 June 2007.

Except where noted otherwise, data relate to standard ambient temperature and pressure.

Disclaimer applies.

Retrieved from “http://en.wikipedia.org/wiki/Benzene_(data_page)
Categories: Chemical data pages | Simple aromatic rings

Dimethylmercury

Sunday, August 31st, 2008

Dimethylmercury

IUPAC name
dimethylmercury

Identifiers

CAS number

Properties

Molecular formula
C2H6Hg

Molar mass
230.659 g/mol

Appearance
Colorless liquid

Density
2.96 g/ml, liquid

Melting point

-43 °C

Boiling point

87 - 97 °C

Solubility in water
Insoluble

Viscosity
 ? cP at ?°C

Hazards

R-phrases
R26, R27, R28,
R33, R50, R53

S-phrases
S13, S28, S36, S45,
S60, S61

Flash point
N/A

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

Dimethylmercury ((CH3)2Hg) is a flammable, colorless liquid, and one of the strongest known neurotoxins. It is described as having a slightly sweet smell, though inhaling enough fumes to notice this would involve significant exposure to the chemical. It is extremely dangerous, with absorption of doses as low as 0.001 mL being fatal. The high vapor pressure of the liquid means that any spillage will result in dangerous levels of exposure to the fumes for those nearby. The molecule adopts a linear structure.

Dimethylmercury crosses the blood-brain barrier easily, probably due to formation of a complex with cysteine. It is eliminated from the organism very slowly, therefore it has tendency to bioaccumulate. The symptoms of poisoning may be delayed by months, possibly too late for effective treatment.

Dimethylmercury passes through latex, PVC, butyl, and neoprene rapidly (within seconds), and is absorbed through the skin. Therefore, most laboratory gloves do not provide adequate protection from it, and the only safe precaution is to handle dimethylmercury while wearing highly resistant laminated gloves underneath long-cuffed neoprene or other heavy-duty gloves. A long face shield and work under a fume hood are also indicated.

The toxicity of dimethylmercury was highlighted when a well-known chemist, Karen Wetterhahn, died several months after spilling a few drops of this compound on her latex-gloved hand.

Contents

//

Use

Dimethylmercury is most often used in toxicology experiments as a fixed point of reference due to its extreme toxicity. It has also been used to calibrate NMR instruments for detection of mercury, although less toxic mercury salts are preferred.

See also

  • Minamata disease
  • Methylmercury
  • Mercury poisoning

References

  1. ^ Simon Cotton, Dimethylmercury and mercury poisoning. The Karen Wetterhahn story. Molecule of the Month.
  2. ^ Hazard Information Bulletin - Dimethylmercury. OSHA Safety and Health Information Bulletins (SHIBs), 1997-1998
  3. ^ Chris Singer (1998-03-10). “199Hg Standards“.
  4. ^ Roy Hoffman (2007-02-21). “Mercury NMR”.

External links

  • ATSDR - ToxFAQs: Mercury
  • ATSDR - Public Health Statement: Mercury
  • ATSDR - ALERT! Patterns of Metallic Mercury Exposure, 6/26/97
  • ATSDR - MMG: Mercury
  • ATSDR - Toxicological Profile: Mercury
  • National Pollutant Inventory - Mercury and compounds Fact Sheet

Retrieved from “http://en.wikipedia.org/wiki/Dimethylmercury
Categories: Organometallic compounds | Mercury compounds | Neurotoxins

Tetramminecopper(II) sulfate

Sunday, August 31st, 2008

Tetramminecopper(II) sulfate

IUPAC name
tetraammine copper(2+) sulfate hydrate

Identifiers

CAS number

PubChem
61513

Properties

Molecular formula
Cu(NH3)4SO4·H2O

Molar mass
245.75 g/mol

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

Tetramminecopper(II) sulfate, formula 2+.

Preparation

This compound can be prepared by adding concentrated ammonia solution, NH3, to a saturated aqueous solution of copper sulfate, CuSO4, until all the copper(II) hydroxide that is initially formed redissolves into a clear deep blue solution. After addition of concentrated ammmonia, crystals will precipitate at the bottom of the flask if kept in an ice-bath or refrigerator to lower the solubility of the complex. The crystals, if washing is desired, should only be washed with anhydrous ethanol containing a drop of concentrated ammonia. Washing with distilled water will lead to hydrolysis to copper(II) hydroxide and ammonia.

Appearance

Tetramminecopper(II) sulfate is a deep blue crystalline solid. The surface is often effloresced and coverred with a powdery light blue layer, especially if kept for a long time. This is the hydrolysed copper(II) hydroxide, along with basic carbonates.

External links

  • National Pollutant Inventory - Copper and compounds fact sheet


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Uranyl zinc acetate

Sunday, August 31st, 2008

Uranyl zinc acetate

IUPAC name
zinc bis(acetato-O)dioxouranate

Other names
zinc uranyl acetate

Identifiers

CAS number

Properties

Molecular formula
ZnUO2(CH3COO)4

Molar mass
571.59 g/mol

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

This article or section contains too much jargon and may need simplification or further explanation.
Please discuss this issue on the talk page, and/or remove or explain jargon terms used in the article. Editing help is available. (January 2008)

Uranyl zinc acetate (ZnUO2(CH3COO)4)is a compound of uranium.

Uranyl zinc acetate is used as a laboratory reagent in the determination of sodium concentrations of solutions using a method of quantitatively precipitating sodium with uranyl zinc acetate and gravimetrically determining the sodium as uranyl zinc sodium acetate, (UO2)2ZnNa(CH3COO)-6H2O. This method was important to determine Na in urine for diagnostic purposes. Zinc uranyl acetate is sometimes called “sodium reagent” since pale yellow NaZn(UO2)3(C2H3O2)9 is one of the very few insoluble sodium compounds.

The process for catalytic synthesis of toluene-2,4-diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene-2,4-diamine (TDA) and DMC, dimethyl toluene-2,4-dicarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 °C, over Zn(OAc)2/alpha–Al2O3 catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250–270 °C and under pressure of 2.7 kPa, over uranyl zinc acetate catalyst, when di-n-octyl sebacate(DOS) is used as heat-carrier, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solvent.

References

The references used in this article may be clearer with a different or consistent style of citation, footnoting, or external linking. (September 2007)

  • Catalytic synthesis of toluene-2,4-diisocyanate from dimethyl carbonate, Wang Y.1; Zhao X.; Li F.; Wang S.1; Zhang J., Journal of Chemical Technology & Biotechnology, 2001, 78, 857-861.


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Categories: Uranyl compounds | Zinc compounds | Acetates | Coordination compounds | Inorganic compound stubsHidden categories: Chemical pages needing a structure drawing | Cleanup from January 2008 | Wikipedia articles needing style editing from January 2008 | All articles needing style editing | Wikipedia references cleanup

Ceric ammonium nitrate

Sunday, August 31st, 2008

Ammonium cerium(IV) nitrate

IUPAC name
Diammonium cerium(IV) nitrate

Other names
Ceric ammonium nitrate (CAN)

Identifiers

CAS number

EINECS number
240-827-6

Properties

Molecular formula
H8N8CeO18

Molar mass
548.26 g/mol

Appearance
orange-red crystals

Melting point

107-108 °C

Solubility in water
141 g/100 mL (25 °C)
227 g/100 mL (80 °C)

Structure

Crystal structure
Monoclinic

Coordination
geometry

Icosahedral

Related compounds

Related compounds
Ammonium nitrate
Cerium(IV) oxide

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

Ceric ammonium nitrate, or in lab jargon “CAN”, is the chemical compound with the formula (NH4)2Ce(NO3)6. This orange-red, water-soluble salt is widely used as an oxidising agent in organic synthesis. This compound is used as a standard oxidant in quantitative analysis,

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Properties and structure

Two components make up this salt, the anion 2- and a pair of NH4+ counter ions, which are not involved in the reactions of CAN. In the anion each nitrato group is chelated to the cerium atom in a bidentate manner as shown below:

Although the N-O bonds (on the metal side of the nitrato group) are unsymmetrical. The anion 2- has idealized Th molecular symmetry. The CeO12 core defines an icosahedron.

Preparation

The anion 2- is generated by dissolving Ce2O3 in hot concentrated HNO3.

Key reactions

(NH4)2Ce(NO3)6 is a stronger oxidizing agent (E° ~ 0.96 V vs. N.H.E.) than even Cl2. Few shelf-stable reagents are stronger oxidants. In the redox process Ce(IV) is converted to Ce(III), a one-electron change, signaled by the fading of the solution color from orange to a pale yellow (providing that the substrate and product are not strongly colored). CAN is useful as an oxidant for many functional groups, some of which are listed below.

  • Oxidation of C-H bonds:
    • Alkenes produces dinitroxylation, although the outcome is solvent-dependent.
    • Methylarenes undergo benzylic oxidation.
  • Oxidation of alcohols, phenols, and ethers
    • Benzylic alcohols are converted into carbonyl compounds.
    • Quinones are produced from catechols and hydroquinones.
  • Oxidation of nitroalkanes
    • An alternative to the Nef reaction, e.g. for ketomacrolide synthesis where complicating side reactions usually encountered using other reagents are avoided using CAN.

Oxidative halogenation can be promoted by CAN as an in situ oxidant, for benzylic bromination, the iodination of ketones and uracil derivatives.

In synthetic organic chemistry the use of protecting groups is basically ubiquitous. Two related protecting groups used to protect alcohols are the para-methoxybenzyl and 3,4-dimethoxybenzyl ethers. They are added to alcohols either as para-methoxybenzyl chloride in the presence of NaH, Ba(OH)2, Ag2O or a stannylene acetal CAN probably works the same way. Since Ce(IV) gains one electron to become Ce(III), two Ce(IV) ions each accept one electron from the para-methoxybenzyl ether to become two Ce(III). Two electrons in total are taken from the para-methoxybenzyl ether. The para-methoxybenzyl ether (minus two electrons) gains a water molecule on the benzylic carbon. The alcohol is remade and the para-methoxybenzyl ether becomes para-methoxybenzaldehyde. The balanced equation is as follows:

2(NH4)2Ce(NO3)6 + H3CO-para-C6H4-CH2-O-R + H2O → 4NH4+ + 2Ce(III) + 12NO3- + 2H+ + H3CO-para-C6H4-CHO + H-O-R

Applications

It has been shown that catalytic amounts of aqueous CAN in tap water can be used to efficiently synthesize various quinoxaline derivates in excellent yields. Quinoxaline derivates are known for their applications in areas such as the following: dyes, organic semiconductors, and DNA cleaving agents. These derivatives are also important components in antibiotics such as Echinomycin and Actinomycin which are known to inhibit the growth of Gram-positive bacteria and can be used against transportable tumors. There are many methods for the synthesis of quinoxaline derivatives, however, most of these suffer from unsatisfactory product yields, expensive metal precursors, harsh reaction conditions for the use of those precursors, as well as other problems. CAN provides both an inexpensive and nontoxic solution to these problems.

CAN has many other synthetic applications, and it sometimes allows to carry out reactions that are not possible using other catalysts. For instance, the CAN-catalyzed three-component reaction between anilines and alkyl vinyl ethers provides an efficient entry into 2-methyl-1,2,3,4-tetrahydroquinolines and the corresponding quinolines obtained by their aromatization.

CAN is also an important component of Chrome etchant, a material that is used in the production of Photomasks and Liquid Crystal Displays.

References

  1. ^ a b c Boons, Geert-Jan.; Hale, Karl J. (2000). Organic Synthesis with Carbohydrates (1st ed.) Sheffield, England: Sheffield Academic Press. pp.33
  2. ^ a b c d e Kocienski, Phillip J. (1994). Protecting Groups Stuttgart, New York Georg Thieme Verlag. pp 8-9, 52-54
  3. ^ Walker, Perrin; William H. Tarn (1991). CRC Handbook of Metal Etchants, 287-291. ISBN 0-8949-3623-6

External links

  • Oxidizing Agents: Cerium Ammonium Nitrate

Retrieved from “http://en.wikipedia.org/wiki/Ceric_ammonium_nitrate
Categories: Ammonium compounds | Cerium compounds | Nitrates | Coordination compounds | Oxidizing agents

Potassium alum

Sunday, August 31st, 2008

Potassium aluminium sulfate

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox references

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Mineral form and occurrence

Potassium alum is a naturally occurring sulfate mineral which typically occurs as encrustations on rocks in areas of weathering and oxidation of sulfide minerals and potassium-bearing minerals. Alunite is an associate and likely potassium and aluminium source. Found at Vesuvius, Italy, East of Springsure, Queensland, Alum Cave, Tennessee, and Alum Gulch, Arizona in the United States, the island of Cebu (Philippines)locally known as tawas.

Uses

Potassium alum is an astringent/styptic and antiseptic. For this reason, it can be used as a natural deodorant by inhibiting the growth of the bacteria responsible for body odor. Use of mineral salts in such a fashion does not prevent perspiration. Its astringent/styptic properties are often employed after shaving and to reduce bleeding in minor cuts and abrasions, nosebleeds, and hemorrhoids. It is frequently used topically and internally in traditional systems of medicine including Ayurveda, where it is called phitkari or saurashtri, and Traditional Chinese Medicine, where it is called ming fan.

References

This article does not cite any references or sources.
Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (February 2008)

External links

  • Potassium Alum: Mineral Data
  • Mindat
  • Uses of Alum in Traditional Chinese Medicine

Retrieved from “http://en.wikipedia.org/wiki/Potassium_alum
Categories: Sulfate minerals | Potassium compounds | Aluminium compounds | Water treatment | Coordination compoundsHidden categories: Chemical pages needing a structure drawing | Articles lacking sources from February 2008 | All articles lacking sources