10-10-02 13:01
No 366860
Mechanically Induced Solid-State Generation of Phosphorus Ylides and the Solvent-Free Wittig Reaction
JACS 124, 6244 (2002)
Mechanical alloying via high-energy ball-milling is a scalable experimental technique, which is broadly used for the preparation and modification of metals, hydrides, and other inorganic solids.
In contrast, mechanochemistry is seldom attempted in organic synthesis, and when it is, mechanical processing of organic reactants is followed by additional treatment (usually heating), or it is carried out in the presence of a solvent. Consequently, little is known about chemical reactions taking place during mechanical milling of organic solids. Furthermore, only indirect evidence confirming just a few chemical transformations of solid organic compounds as a result of milling has been presented to date.
../rhodium/pdf /ballmilling.w
Alcohol, an unconsciousness-expanding drug
(Hive Bee)
10-11-02 06:37
No 367157
Has an article about that too I can't remember the month of the issue it's 2002 though.
(Chief Bee)
10-11-02 11:56
No 367258
That's the publication where I found the above reference in. I think it might have been in the "What is Time?" special issue.
(Hive Bee)
10-12-02 02:10
No 367464
Post 336172 (CrystalDaddy: ""The toxic solvents of organic chemistry could..."", Chemistry Discourse)
(Stranger)
10-28-02 07:34
No 373495
New Scientist had such an article also will have a look through my collection and try and find it, it was specifically to do with organics I believe because they were talking about its experimental use for the paper industry instead of solvents all tho not entirley familiar with the pulp and paper industry chem usage.
10-29-02 20:09
(Rated as: off-topic)
(Stranger)
10-30-02 08:03
No 374409
Smashing steel balls together is the latest idea in the drive to make chemical synthesis more environmentally friendly. The collisions provide the right conditions to drive reactions between organic compounds without the need for harmful solvents.
Organic chemicals often have a stable crystal structure that locks up their molecules, making them unreactive. To persuade the molecules of different chemicals to mix and react, they must normally be dissolved in a solvent such as benzene or toluene. But the solvents can't be reused and are often toxic or harmful to the environment.
Researchers have investigated alternatives such as microwaves and hot pressurised water, but none has been cheap or efficient nough to persuade industry to give up solvents. Now chemists in the US have come up with a mechanical approach. Viktor Balema and his colleages at the government's Ames Laboratory in Iowa took their inspiration from ball milling, a process already used in industry to produce and modify metal alloys by shaking them in vials of ball bearings.
When they tried the technique with organic chemicals, the researchers noticed small chemical changes taking place in their samples. So they decided to check whether it was possible to use the balls to make completely new compounds. They chose several well-known reactions to test this out, including the Wittig reaction, which produces unsaturated hydrocarbons. These are used as building blocks in the preparation of many organic materials and pharmaceuticals.
The researchers shook the reactants and the small steel balls together for several hours. Then they measured what happened using a variety of techniques, including x-ray diffraction and nuclear magnetic resonance. The reactions all proceeded very efficiently, in some cases giving even higher yields than the solvents.
There you go an extract from New Scientist NZ/Auz version July 19 page 19
Sounds promising eh? also read another article somewhere about an organic reaction using much less solvent than normal and having glass balls, so making a slurry of reactants with a minimum of solvent and then putting in glass balls and using some kickass mag stirring.... hope this helps...
almost enough posts to not make me a stranger anymore!!!!
(Hive Bee)
11-09-02 05:08
No 377885
How Did We Split That Water?
Japanese researchers at the Tokyo Institute of Technology say they've found a way to split water by using a mechano-catalysts. The group claims that Cu(I) oxide can catalyze the splitting of water into hydrogen and oxygen in visible light. But, when the lights went out the real fun started! The gases continued to evolve several hundred hours after the light was turned off!
Similar results were seen with other binary oxides such as NiO, Co3O4, and Fe3O4. The researchers think that the mechanical energy supplied by stirring is converted to chemical energy by the oxide catalysts. Not everyone is ready to embrace this theory though.
Dr. Michael Gratzel of the Swiss Federal Institute of Technology thinks that the electrical charging of the powder (by friction) followed by local discharge may cause the splitting of the water molecules.
Mr. Arthur Nozik of the of the National Renewable Energy Laboratory in Golden, Colorado proposes that the oxides react directly with the water through an auto- redox reaction to produce hydrogen and oxygen.
However it's accomplished, it may be a more cost effective way to produce hydrogen and oxygen as opposed to traditional electroylosis. We'll just have to wait and see.
from:
http://www.cheresources.com/watersplitzz
A serious page on chemical engineering with many articles online, worth a visit anyways. Have a look it is a treasure box! (has perhaps already been posted)
ORGY