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It:Osmium Tetroxide

2006-12-07T21:20:52Z

Sdc05:

=Introduction1=

Chemical Formula: OsO4
Molar Mass: 254.23 gmol-1
Melting point: 40°C
Boiling point: 130°C
VERY TOXIC Especially to the eyes.
Colourless/Yellow
Ozonelike odour

Osmium Tetroxide is an example of the highest oxidation state achieved by transition metal. It has a tetrahedral shape as shown in jmol format below with O=Os=O bond angle of ~109°.

<jmol>
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<inlineContents>HEADER CSD ENTRY XICKAV
HEADER NONAME 07-Dec-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 07-Dec-06 0 NONE 4
ATOM 1 O 0 0.000 -1.424 -1.007 0.00 0.00 O+0
ATOM 2 Os 0 -0.000 -0.000 0.000 0.00 0.00 Os+0
ATOM 3 O 0 0.000 1.424 -1.007 0.00 0.00 O+0
ATOM 4 O 0 -1.424 0.000 1.007 0.00 0.00 O+0
ATOM 5 O 0 1.424 -0.000 1.007 0.00 0.00 O+0
CONECT 1 2 0 0 0 NONE 10
CONECT 2 1 3 4 5 NONE 11
CONECT 3 2 0 0 0 NONE 12
CONECT 4 2 0 0 0 NONE 13
CONECT 5 2 0 0 0 NONE 14
END NONE 15
END</inlineContents>
</jmolApplet>
</jmol>

===Weapon of terror?===
Osmium Tetroxide has been seen as a possible terrorist weapon, this is becuase of its possible use as a catalysist in an explosive device, or due to its high toxicity. The catalytic behaviour is possible due to osmium’s many oxidation states, and the toxicity because of its acidic and corrosive nature in aqueous systems. However it's cost has had it dubbed 'the billionaires weapon'.

=Preparation1=

Addition of oxygen by burning the metal at 800 °C

[[Image:OsO4.JPG|Thumb|Left|200|Preparation]]

=Use in Organic Chemistry=

Oxidation of C=C bond1

[[Image:OsO4 oxidation.JPG|Thumb|Left|200|Reaction]]

Osmium forms several oxofluorides, all of which are very sensitive to moisture. Purple cis-OsO2F4 forms at 77 K in an aqueous solution of HF3

OsO4 + 2 KrF2 → cis-OsO2F4 + 2 Kr + O2
OsO4 also reacts with F2 to form yellow OsOF2:

2 OsO4 + 2 F2 → 2 OsO3F2 + O2
OsO4 reacts with one equivalent of [Me4N]F at 298 K and 2 equivalents at 253 K[4]:

OsO4 + [Me4N]F → [Me4N][OsO4F]
OsO4 + 2 [Me4N]F → [Me4N]2[cis-OsO4F2]

==References==
1.http://www.chm.bris.ac.uk/motm/oso4/oso4v.htm

2.http://news.bbc.co.uk/1/hi/uk/3604857.stm

3.Christe et al. Osmium Tetrafluoride Dioxide, cis-OsO2F4. J. Am. Chem. Soc. 1993, 115. 11279-11284

4. http://en.wikipedia.org/wiki/Osmium_tetroxide

It:Osmium Tetroxide

2006-12-07T12:09:27Z

Sdc05:

=Introduction1=
Chemical Formula: OsO4
==Physical Properties==
Melting point: 40°C
Boiling point: 130°C
VERY TOXIC Especially to the eyes.
Colourless/Yellow
Ozonelike odour

Osmium Tetroxide is an example of the highest oxidation state achieved by transition metal. It has a tetrahedral shape as shown in jmol format below with O=Os=O bond angle of ~109°.

<jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
HEADER NONAME 07-Dec-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 07-Dec-06 0 NONE 4
ATOM 1 O 0 0.000 -1.424 -1.007 0.00 0.00 O+0
ATOM 2 Os 0 -0.000 -0.000 0.000 0.00 0.00 Os+0
ATOM 3 O 0 0.000 1.424 -1.007 0.00 0.00 O+0
ATOM 4 O 0 -1.424 0.000 1.007 0.00 0.00 O+0
ATOM 5 O 0 1.424 -0.000 1.007 0.00 0.00 O+0
CONECT 1 2 0 0 0 NONE 10
CONECT 2 1 3 4 5 NONE 11
CONECT 3 2 0 0 0 NONE 12
CONECT 4 2 0 0 0 NONE 13
CONECT 5 2 0 0 0 NONE 14
END NONE 15
END</inlineContents>
</jmolApplet>
</jmol>

=Preparation1=

Addition of oxygen by burning the metal at 800 °C

[[Image:OsO4.JPG|Thumb|Left|200|Preparation]]

=Use in Organic Chemistry=

Oxidation of C=C bond

[[Image:OsO4 oxidation.JPG|Thumb|Left|200|Reaction]]

==References==
1.http://www.chm.bris.ac.uk/motm/oso4/oso4v.htm

File:OsO4 oxidation.JPG

2006-12-07T12:07:13Z

Sdc05:

File:OsO4.JPG

2006-12-07T12:00:54Z

Sdc05:

It:Osmium Tetroxide

2006-12-07T11:46:09Z

Sdc05:

<jmol>
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<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
HEADER NONAME 07-Dec-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 07-Dec-06 0 NONE 4
ATOM 1 O 0 0.000 -1.424 -1.007 0.00 0.00 O+0
ATOM 2 Os 0 -0.000 -0.000 0.000 0.00 0.00 Os+0
ATOM 3 O 0 0.000 1.424 -1.007 0.00 0.00 O+0
ATOM 4 O 0 -1.424 0.000 1.007 0.00 0.00 O+0
ATOM 5 O 0 1.424 -0.000 1.007 0.00 0.00 O+0
CONECT 1 2 0 0 0 NONE 10
CONECT 2 1 3 4 5 NONE 11
CONECT 3 2 0 0 0 NONE 12
CONECT 4 2 0 0 0 NONE 13
CONECT 5 2 0 0 0 NONE 14
END NONE 15
END</inlineContents>
</jmolApplet>
</jmol>

It:projects

2006-12-07T11:38:19Z

Sdc05: /* Supplemental Project Page */

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It:Schrock

2006-11-20T17:18:46Z

Sdc05: /* Introduction */

==Introduction==
[[Image:Schrock2.jpg|thumb|left|General example, commercially available example2]]

This is an important discovery as the catalysts used before were sensitive to air and moisture, created side reactions and were relatively short-lived.2 Schrock's discovery of the catalysts using tungsten provided one of the first stable metathesis catalyst.2

<jmol>
<jmolApplet>
<size>400</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000

HEADER NONAME 20-Nov-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 20-Nov-06 0 NONE 4
ATOM 1 C 0 2.963 -1.542 0.211 0.00 0.00 C+0
ATOM 2 C 0 1.711 -2.418 0.287 0.00 0.00 C+0
ATOM 3 C 0 1.225 -2.737 -1.129 0.00 0.00 C+0
ATOM 4 C 0 2.043 -3.720 1.018 0.00 0.00 C+0
ATOM 5 O 0 0.685 -1.722 0.997 0.00 0.00 O+0
ATOM 6 W 0 0.327 -0.023 -0.017 0.00 0.00 W+0
ATOM 7 N 0 -1.038 0.906 0.803 0.00 0.00 N+0
ATOM 8 C 0 -2.234 0.351 0.930 0.00 0.00 C+0
ATOM 9 C 0 -3.290 1.059 1.560 0.00 0.00 C+0
ATOM 10 C 0 -4.515 0.474 1.682 0.00 0.00 C+0
ATOM 11 C 0 -4.733 -0.808 1.195 0.00 0.00 C+0
ATOM 12 C 0 -3.710 -1.515 0.576 0.00 0.00 C+0
ATOM 13 C 0 -2.475 -0.955 0.432 0.00 0.00 C+0
ATOM 14 O 0 1.989 1.107 -0.037 0.00 0.00 O+0
ATOM 15 C 0 1.961 1.904 1.149 0.00 0.00 C+0
ATOM 16 C 0 1.778 0.998 2.368 0.00 0.00 C+0
ATOM 17 C 0 3.278 2.673 1.277 0.00 0.00 C+0
ATOM 18 C 0 0.798 2.895 1.070 0.00 0.00 C+0
ATOM 19 C 0 -0.176 -0.444 -1.804 0.00 0.00 C+0
ATOM 20 C 0 -0.600 0.653 -2.746 0.00 0.00 C+0
ATOM 21 C 0 -0.395 2.011 -2.072 0.00 0.00 C+0
ATOM 22 C 0 0.243 0.584 -4.021 0.00 0.00 C+0
ATOM 23 C 0 -2.078 0.478 -3.101 0.00 0.00 C+0
ATOM 24 H 0 2.744 -0.644 -0.367 0.00 0.00 H+0
ATOM 25 H 0 3.270 -1.260 1.217 0.00 0.00 H+0
ATOM 26 H 0 3.766 -2.098 -0.272 0.00 0.00 H+0
ATOM 27 H 0 1.773 -3.596 -1.516 0.00 0.00 H+0
ATOM 28 H 0 0.160 -2.967 -1.104 0.00 0.00 H+0
ATOM 29 H 0 1.396 -1.876 -1.774 0.00 0.00 H+0
ATOM 30 H 0 2.389 -3.493 2.026 0.00 0.00 H+0
ATOM 31 H 0 1.151 -4.344 1.072 0.00 0.00 H+0
ATOM 32 H 0 2.826 -4.251 0.476 0.00 0.00 H+0
ATOM 33 H 0 -3.123 2.056 1.940 0.00 0.00 H+0
ATOM 34 H 0 -5.321 1.010 2.162 0.00 0.00 H+0
ATOM 35 H 0 -5.708 -1.261 1.298 0.00 0.00 H+0
ATOM 36 H 0 -3.894 -2.512 0.202 0.00 0.00 H+0
ATOM 37 H 0 -1.681 -1.507 -0.049 0.00 0.00 H+0
ATOM 38 H 0 2.649 0.351 2.473 0.00 0.00 H+0
ATOM 39 H 0 1.670 1.610 3.263 0.00 0.00 H+0
ATOM 40 H 0 0.885 0.387 2.236 0.00 0.00 H+0
ATOM 41 H 0 3.408 3.318 0.409 0.00 0.00 H+0
ATOM 42 H 0 3.257 3.280 2.182 0.00 0.00 H+0
ATOM 43 H 0 4.107 1.967 1.333 0.00 0.00 H+0
ATOM 44 H 0 -0.135 2.378 1.296 0.00 0.00 H+0
ATOM 45 H 0 0.953 3.696 1.793 0.00 0.00 H+0
ATOM 46 H 0 0.746 3.316 0.066 0.00 0.00 H+0
ATOM 47 H 0 -0.158 -1.470 -2.142 0.00 0.00 H+0
ATOM 48 H 0 0.658 2.136 -1.818 0.00 0.00 H+0
ATOM 49 H 0 -0.702 2.805 -2.753 0.00 0.00 H+0
ATOM 50 H 0 -0.996 2.060 -1.163 0.00 0.00 H+0
ATOM 51 H 0 0.032 -0.348 -4.546 0.00 0.00 H+0
ATOM 52 H 0 -0.004 1.428 -4.665 0.00 0.00 H+0
ATOM 53 H 0 1.300 0.623 -3.760 0.00 0.00 H+0
ATOM 54 H 0 -2.678 0.527 -2.192 0.00 0.00 H+0
ATOM 55 H 0 -2.384 1.271 -3.782 0.00 0.00 H+0
ATOM 56 H 0 -2.224 -0.490 -3.581 0.00 0.00 H+0
CONECT 1 2 24 25 26 NONE 61
CONECT 2 1 3 4 5 NONE 62
CONECT 3 2 27 28 29 NONE 63
CONECT 4 2 30 31 32 NONE 64
CONECT 5 2 6 0 0 NONE 65
CONECT 6 5 7 14 19 NONE 66
CONECT 7 6 8 0 0 NONE 67
CONECT 8 7 13 9 0 NONE 68
CONECT 9 8 10 33 0 NONE 69
CONECT 10 9 11 34 0 NONE 70
CONECT 11 10 12 35 0 NONE 71
CONECT 12 11 13 36 0 NONE 72
CONECT 13 12 8 37 0 NONE 73
CONECT 14 6 15 0 0 NONE 74
CONECT 15 14 16 17 18 NONE 75
CONECT 16 15 38 39 40 NONE 76
CONECT 17 15 41 42 43 NONE 77
CONECT 18 15 44 45 46 NONE 78
CONECT 19 6 20 47 0 NONE 79
CONECT 20 19 21 22 23 NONE 80
CONECT 21 20 48 49 50 NONE 81
CONECT 22 20 51 52 53 NONE 82
CONECT 23 20 54 55 56 NONE 83
END</inlineContents>
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An example of Schrock Metathesis catalyst in 3-D.

Reference

1.http://www.rsc.org/chemistryworld/restricted/2005/November/prize.asp

It:Schrock

2006-11-20T17:11:05Z

Sdc05: /* Introduction */

File:Schrock2.jpg

2006-11-20T17:01:18Z

Sdc05:

It:Schrock

2006-11-20T17:01:06Z

Sdc05:

==Introduction==

[[image:schrock.JPG|thumb|left|200|schrock]]
From reference 1.

This is an important discovery as the catalysts used before were sensitive to air and moisture, created side reactions and were relatively short-lived.2

Reference
1.http://www.strem.com/code/technical_notes/74-1800tech.pdf

File:Schrock.JPG

2006-11-20T16:43:35Z

Sdc05:

It:knots

2006-11-20T16:26:54Z

Sdc05: /* knots */

===knots===

[[Image:knots.jpg|thumb|left|300|reference1]]
The simplest knotted molecule so far.

Reference
1. http://plus.maths.org/issue15/features/knots/index.html

It:knots

2006-11-20T15:53:14Z

Sdc05:

===knots===

[[Image:knots.jpg|thumb|left|300|reference1]]

It:knots

2006-11-20T15:52:56Z

Sdc05:

===knots===

[[Image:knots.jpg|thumb|left|300|reference 1]

File:Knots.jpg

2006-11-20T15:48:10Z

Sdc05:

It:Methylaluminoxane

2006-11-20T15:43:57Z

Sdc05: /* Introduction */

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Introduction==

Methylaluminoxane or MAO [(-Al(CH3)O-)n] is a white solid. It is primarily used as a catalyst component in the Ziegler-Natta systems for olefin polymerization.

MAO reacts vigorously with any chemical with an acidic proton. It is highly soluble in hydrocarbon and hence it is usually used as a solution.

<jmol>
<jmolApplet>
<size>100</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
HEADER NONAME 20-Nov-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 20-Nov-06 0 NONE 4
ATOM 1 C 0 -0.663 2.118 1.018 0.00 0.00 C+0
ATOM 2 Al 0 -0.174 0.786 -0.261 0.00 0.00 Al+0
ATOM 3 O 0 1.449 0.775 -0.942 0.00 0.00 O+0
ATOM 4 Al 0 2.401 -0.344 0.028 0.00 0.00 Al+0
ATOM 5 O 0 1.628 -1.282 1.301 0.00 0.00 O+0
ATOM 6 C 0 4.272 -0.539 -0.300 0.00 0.00 C+0
ATOM 7 O 0 -1.345 -0.430 -0.757 0.00 0.00 O+0
ATOM 8 Al 0 -2.830 -0.097 0.127 0.00 0.00 Al+0
ATOM 9 C 0 -4.364 -1.204 -0.131 0.00 0.00 C+0
ATOM 10 H 0 0.210 2.723 1.265 0.00 0.00 H+0
ATOM 11 H 0 -1.440 2.757 0.598 0.00 0.00 H+0
ATOM 12 H 0 -1.038 1.635 1.920 0.00 0.00 H+0
ATOM 13 H 0 4.568 0.117 -1.118 0.00 0.00 H+0
ATOM 14 H 0 4.828 -0.272 0.599 0.00 0.00 H+0
ATOM 15 H 0 4.488 -1.573 -0.567 0.00 0.00 H+0
ATOM 16 H 0 -4.667 -1.167 -1.178 0.00 0.00 H+0
ATOM 17 H 0 -4.121 -2.231 0.140 0.00 0.00 H+0
ATOM 18 H 0 -5.181 -0.846 0.496 0.00 0.00 H+0
CONECT 1 2 10 11 12 NONE 23
CONECT 2 1 3 7 0 NONE 24
CONECT 3 2 4 0 0 NONE 25
CONECT 4 3 5 6 0 NONE 26
CONECT 5 4 0 0 0 NONE 27
CONECT 6 4 13 14 15 NONE 28
CONECT 7 2 8 0 0 NONE 29
CONECT 8 7 9 0 0 NONE 30
CONECT 9 8 16 17 18 NONE 31
END</inlineContents>
</jmolApplet>
</jmol>

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

[[Image:Methylaluminoxane.gif|thumb|center|200|Structure of Methylaluminoxane]]

== Properties ==
MAO is a complex mixture of linear and cyclic oligomeric aluminxanes containing 20-30 wt. % trimethylalumnium. MAO is pyrophoric meaning it ignites spontaneously since its autoignition is below the room temperature. It has a high solubility in aromatic hydrocarbons such as toluene, xylene, cumene and mesitylene. In aliphatic hydrocarbons it has a lower solubility. This property depends on its Mr, composition and trimethylaluminium content.
[http://www.albemarle.com/acrofiles/sc2008f_MAO_datasheet.pdf]

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-11-20T15:43:18Z

Sdc05: /* Structure */

It:Methylaluminoxane

2006-11-20T15:42:56Z

Sdc05: /* Structure */

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Introduction==

Methylaluminoxane or MAO [(-Al(CH3)O-)n] is a white solid. It is primarily used as a catalyst component in the Ziegler-Natta systems for olefin polymerization.

MAO reacts vigorously with any chemical with an acidic proton. It is highly soluble in hydrocarbon and hence it is usually used as a solution.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

[[Image:Methylaluminoxane.gif|thumb|center|200|Structure of Methylaluminoxane]]
<jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
HEADER NONAME 20-Nov-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 20-Nov-06 0 NONE 4
ATOM 1 C 0 -0.663 2.118 1.018 0.00 0.00 C+0
ATOM 2 Al 0 -0.174 0.786 -0.261 0.00 0.00 Al+0
ATOM 3 O 0 1.449 0.775 -0.942 0.00 0.00 O+0
ATOM 4 Al 0 2.401 -0.344 0.028 0.00 0.00 Al+0
ATOM 5 O 0 1.628 -1.282 1.301 0.00 0.00 O+0
ATOM 6 C 0 4.272 -0.539 -0.300 0.00 0.00 C+0
ATOM 7 O 0 -1.345 -0.430 -0.757 0.00 0.00 O+0
ATOM 8 Al 0 -2.830 -0.097 0.127 0.00 0.00 Al+0
ATOM 9 C 0 -4.364 -1.204 -0.131 0.00 0.00 C+0
ATOM 10 H 0 0.210 2.723 1.265 0.00 0.00 H+0
ATOM 11 H 0 -1.440 2.757 0.598 0.00 0.00 H+0
ATOM 12 H 0 -1.038 1.635 1.920 0.00 0.00 H+0
ATOM 13 H 0 4.568 0.117 -1.118 0.00 0.00 H+0
ATOM 14 H 0 4.828 -0.272 0.599 0.00 0.00 H+0
ATOM 15 H 0 4.488 -1.573 -0.567 0.00 0.00 H+0
ATOM 16 H 0 -4.667 -1.167 -1.178 0.00 0.00 H+0
ATOM 17 H 0 -4.121 -2.231 0.140 0.00 0.00 H+0
ATOM 18 H 0 -5.181 -0.846 0.496 0.00 0.00 H+0
CONECT 1 2 10 11 12 NONE 23
CONECT 2 1 3 7 0 NONE 24
CONECT 3 2 4 0 0 NONE 25
CONECT 4 3 5 6 0 NONE 26
CONECT 5 4 0 0 0 NONE 27
CONECT 6 4 13 14 15 NONE 28
CONECT 7 2 8 0 0 NONE 29
CONECT 8 7 9 0 0 NONE 30
CONECT 9 8 16 17 18 NONE 31
END</inlineContents>
</jmolApplet>
</jmol>

== Properties ==
MAO is a complex mixture of linear and cyclic oligomeric aluminxanes containing 20-30 wt. % trimethylalumnium. MAO is pyrophoric meaning it ignites spontaneously since its autoignition is below the room temperature. It has a high solubility in aromatic hydrocarbons such as toluene, xylene, cumene and mesitylene. In aliphatic hydrocarbons it has a lower solubility. This property depends on its Mr, composition and trimethylaluminium content.
[http://www.albemarle.com/acrofiles/sc2008f_MAO_datasheet.pdf]

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-11-20T15:42:09Z

Sdc05: /* Structure */

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Introduction==

Methylaluminoxane or MAO [(-Al(CH3)O-)n] is a white solid. It is primarily used as a catalyst component in the Ziegler-Natta systems for olefin polymerization.

MAO reacts vigorously with any chemical with an acidic proton. It is highly soluble in hydrocarbon and hence it is usually used as a solution.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

[[Image:Methylaluminoxane.gif|thumb|center|200|Structure of Methylaluminoxane]]

<jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
HEADER NONAME 20-Nov-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 20-Nov-06 0 NONE 4
ATOM 1 C 0 -0.663 2.118 1.018 0.00 0.00 C+0
ATOM 2 Al 0 -0.174 0.786 -0.261 0.00 0.00 Al+0
ATOM 3 O 0 1.449 0.775 -0.942 0.00 0.00 O+0
ATOM 4 Al 0 2.401 -0.344 0.028 0.00 0.00 Al+0
ATOM 5 O 0 1.628 -1.282 1.301 0.00 0.00 O+0
ATOM 6 C 0 4.272 -0.539 -0.300 0.00 0.00 C+0
ATOM 7 O 0 -1.345 -0.430 -0.757 0.00 0.00 O+0
ATOM 8 Al 0 -2.830 -0.097 0.127 0.00 0.00 Al+0
ATOM 9 C 0 -4.364 -1.204 -0.131 0.00 0.00 C+0
ATOM 10 H 0 0.210 2.723 1.265 0.00 0.00 H+0
ATOM 11 H 0 -1.440 2.757 0.598 0.00 0.00 H+0
ATOM 12 H 0 -1.038 1.635 1.920 0.00 0.00 H+0
ATOM 13 H 0 4.568 0.117 -1.118 0.00 0.00 H+0
ATOM 14 H 0 4.828 -0.272 0.599 0.00 0.00 H+0
ATOM 15 H 0 4.488 -1.573 -0.567 0.00 0.00 H+0
ATOM 16 H 0 -4.667 -1.167 -1.178 0.00 0.00 H+0
ATOM 17 H 0 -4.121 -2.231 0.140 0.00 0.00 H+0
ATOM 18 H 0 -5.181 -0.846 0.496 0.00 0.00 H+0
CONECT 1 2 10 11 12 NONE 23
CONECT 2 1 3 7 0 NONE 24
CONECT 3 2 4 0 0 NONE 25
CONECT 4 3 5 6 0 NONE 26
CONECT 5 4 0 0 0 NONE 27
CONECT 6 4 13 14 15 NONE 28
CONECT 7 2 8 0 0 NONE 29
CONECT 8 7 9 0 0 NONE 30
CONECT 9 8 16 17 18 NONE 31
END</inlineContents>
</jmolApplet>
</jmol>

== Properties ==
MAO is a complex mixture of linear and cyclic oligomeric aluminxanes containing 20-30 wt. % trimethylalumnium. MAO is pyrophoric meaning it ignites spontaneously since its autoignition is below the room temperature. It has a high solubility in aromatic hydrocarbons such as toluene, xylene, cumene and mesitylene. In aliphatic hydrocarbons it has a lower solubility. This property depends on its Mr, composition and trimethylaluminium content.
[http://www.albemarle.com/acrofiles/sc2008f_MAO_datasheet.pdf]

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-11-20T15:41:55Z

Sdc05: /* Properties */

It:Methylaluminoxane

2006-11-20T15:41:17Z

Sdc05: /* Properties */

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Introduction==

Methylaluminoxane or MAO [(-Al(CH3)O-)n] is a white solid. It is primarily used as a catalyst component in the Ziegler-Natta systems for olefin polymerization.

MAO reacts vigorously with any chemical with an acidic proton. It is highly soluble in hydrocarbon and hence it is usually used as a solution.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

[[Image:Methylaluminoxane.gif|thumb|center|200|Structure of Methylaluminoxane]]

== Properties ==
MAO is a complex mixture of linear and cyclic oligomeric aluminxanes containing 20-30 wt. % trimethylalumnium. MAO is pyrophoric meaning it ignites spontaneously since its autoignition is below the room temperature. It has a high solubility in aromatic hydrocarbons such as toluene, xylene, cumene and mesitylene. In aliphatic hydrocarbons it has a lower solubility. This property depends on its Mr, composition and trimethylaluminium content.
[http://www.albemarle.com/acrofiles/sc2008f_MAO_datasheet.pdf]

<jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
HEADER NONAME 20-Nov-06 NONE 1
TITLE NONE 2
AUTHOR WWW daemon apache NONE 3
REVDAT 1 20-Nov-06 0 NONE 4
ATOM 1 C 0 -0.663 2.118 1.018 0.00 0.00 C+0
ATOM 2 Al 0 -0.174 0.786 -0.261 0.00 0.00 Al+0
ATOM 3 O 0 1.449 0.775 -0.942 0.00 0.00 O+0
ATOM 4 Al 0 2.401 -0.344 0.028 0.00 0.00 Al+0
ATOM 5 O 0 1.628 -1.282 1.301 0.00 0.00 O+0
ATOM 6 C 0 4.272 -0.539 -0.300 0.00 0.00 C+0
ATOM 7 O 0 -1.345 -0.430 -0.757 0.00 0.00 O+0
ATOM 8 Al 0 -2.830 -0.097 0.127 0.00 0.00 Al+0
ATOM 9 C 0 -4.364 -1.204 -0.131 0.00 0.00 C+0
ATOM 10 H 0 0.210 2.723 1.265 0.00 0.00 H+0
ATOM 11 H 0 -1.440 2.757 0.598 0.00 0.00 H+0
ATOM 12 H 0 -1.038 1.635 1.920 0.00 0.00 H+0
ATOM 13 H 0 4.568 0.117 -1.118 0.00 0.00 H+0
ATOM 14 H 0 4.828 -0.272 0.599 0.00 0.00 H+0
ATOM 15 H 0 4.488 -1.573 -0.567 0.00 0.00 H+0
ATOM 16 H 0 -4.667 -1.167 -1.178 0.00 0.00 H+0
ATOM 17 H 0 -4.121 -2.231 0.140 0.00 0.00 H+0
ATOM 18 H 0 -5.181 -0.846 0.496 0.00 0.00 H+0
CONECT 1 2 10 11 12 NONE 23
CONECT 2 1 3 7 0 NONE 24
CONECT 3 2 4 0 0 NONE 25
CONECT 4 3 5 6 0 NONE 26
CONECT 5 4 0 0 0 NONE 27
CONECT 6 4 13 14 15 NONE 28
CONECT 7 2 8 0 0 NONE 29
CONECT 8 7 9 0 0 NONE 30
CONECT 9 8 16 17 18 NONE 31
END</inlineContents>
</jmolApplet>
</jmol>

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-10-22T16:24:47Z

Sdc05: /* METHYLALUMINOXANE: */

= METHYLALUMINOXANE: =

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Introduction==

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-10-22T16:19:30Z

Sdc05: /* METHYLALUMINOXANE: */

= METHYLALUMINOXANE: =

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971

2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370

3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171

4.http://en.wikipedia.org/wiki/Methylaluminoxane

5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-10-22T15:14:42Z

Sdc05: /* Activating the catalyst */

= METHYLALUMINOXANE: =

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

This equation illustrates the possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971
2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370
3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171
4.http://en.wikipedia.org/wiki/Methylaluminoxane
5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

It:Methylaluminoxane

2006-10-22T15:13:31Z

Sdc05: /* METHYLALUMINOXANE: */

= METHYLALUMINOXANE: =

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

==Structure==
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound.1 Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria.2 The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.3

==Synthesis==
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.3

==Proposed mechanisms for its uses==

===Activating the catalyst===
[[Image:MAOactivator.JPG]]5

It is generally believed that MAO alkylates and then activates the metal-chloride pre-catalyst species, forming an ion pair which should allow ethene insertion.4

[[Image:MAO2.JPG]]1

Possible role of the product cation as a catalyst in olefin polymerisation

==References==
1.Mason, M. R.; Smith, J. M.; Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1993, 115, 4971
2.E. Zurek, T. K. Woo, T. K. Firman, T. Ziegler, Inorg. Chem. 2001, 40, 361-370
3.S. Srinivasa Reddy, K. Radhakrishnan, S. Sivaram, Polymer Bulletin. 1996, 36, 165-171
4.http://en.wikipedia.org/wiki/Methylaluminoxane
5.Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem. 1980, 92, 396

File:MAO2.JPG

2006-10-22T15:02:12Z

Sdc05:

It:Methylaluminoxane

2006-10-22T14:55:00Z

Sdc05:

== METHYLALUMINOXANE: ==

Methylaluminoxane, also known as MAO, is mostly used as an important cocatalyst for Ziegler-Natta polymerisations of alkenes.

===Structure===
The precise structure of Methylaluminoxane is largely unknown as it is not possible to isolate the crystalline sample of this compound. Also, NMR studies of this compound is hindered by disproportionation reactions at high temperatures and association in solution yielding a mixture of different oligomers with multiple equilibria. The general chemical formula of this compound is (-Al(CH3)O-)n where Oxygen joins two aluminium atoms that still bear a CH3 group.

===Synthesis===
MAO is generally prepared by partial hydrolysis of trimethylaluminum, TMA. This is done using hydrated salt dispersed in toluene. Depending on the nature of the salt used and the reaction conditions, MAO with widely differing activities as cocatalysts in polymerization of ethylene is formed.

===Activating the catalyst===
[[Image:MAOactivator.JPG]]

File:MAOactivator.JPG

2006-10-22T14:36:13Z

Sdc05: It is believed that MAO acts as a cocatalyst by activating the catalyst through this kind of reaction

It is believed that MAO acts as a cocatalyst by activating the catalyst through this kind of reaction