NEWSCRIPTS Periodic table wins award
Alpha Olefins Answers with Eduardo J. Baralt, Ph.D.
Q
m\ am developing a transition metal alkyl •complex using a long alkyl chain alpha olefin. Because I want increased yields, I plan to utilize your new C26/28 normal alpha olefin (ΝΑΟ) fraction with its high alpha content. I find product yield variability and sometimes it is difficult to drive conversion above 70%. I have sent you a sample of the reaction product for analysis. Can you help?
A
When using a moisture/oxygen sensitive • metal complex, there are a few critical things to check for to keep the yield as high as possible. Make sure that the reagents and solvents are free of water and oxygen. If the ΝΑΟ has been previously exposed to air, it may have formed oxygenates such as peroxides and carbonyls and may have absorbed water in ppm levels. Also, find out if your complex is tempera ture sensitive or decomposes with time. Analysis of your sample by 13C-NMR and GC clearly shows formation of C26-28 dimer and isomerization of the C26-28 ΝΑΟ. This may be caused by having your metal complex acting as an alpha olefin dimerization catalyst. m
Dimerization N
vrM^/\^-
M
X
Also, ΝΑΟ isomerization occurs as shown below to form cis/trans-2-olefins and other internal olefins. Our analysis shows that the pre dominant internal olefins are cis/trans-2-olefins. Analysis by other techniques does not reveal organic or inorganic contaminants in the sample. Isomerization
If further support is needed on this or other alpha olefins matters, please contact us. We are delighted to provide technical support to our customers.
CPChem www.cpchem.com P.O. Box 3766, Houston, Texas 77253 TEL 979.548.0466 · TOLL-FREE 800.231.3260 FAX 713.289.4925 E-mail:
[email protected] A periodic table of the ele ments website at Los Alamos National Laboratory in New Mexico has been named one of BY K. M. the 50 best "Web sources in sci ence and technology The award was one of the 2001 Sci/Tech Web Awards made by ScientificAmerican.com, part of Sci entific American magazine. The Los Alamos site is linked to the laboratory's chemical division. It is main tained and updated by computer techni cian Nick Degidio and staff member Moses Attrep. Degidio says, "We aver age about 30,000 hits a month ... and that number doubles aroundfinals,term papers, and midterm exam time." The site has been ninning about four years. It was designed originally to be an internal source but has evolved into an external source for chemistry students in the mid dle and high school age group. The site can be found at http:// www.periodic.lanl.gov/. It has links to every element, answers to frequently asked questions, and provisions for ask ing new questions. The aspect of the site that tickles Degidio and Attrep is the questions from kids new to chemistry. Degidio screens them, answers those that don't deal directly with chemistry, and gives the rest to Attrep, a veteran teacher of chemistry who can tell what the kids are up to. A student named Aaron, of unknown age, asked 13 questions, including, "What are the alkaline earth metals and what main characteristics do they possess?" Says Attrep: 'Aaron was dumpinghis homework onme. Sol ...let him know that the answers to his questions were all there in his text book and that he should try studying."
Curves and cannons The story about LymanJ. Briggs and the curve ball (C&EN, April 30, page 64) reminded M. R. J. Wyllie, Troy, Va., of "some work I did in 1943 as ayoung naval officer at the Admiralty in London." He was looking into alternative uses for BainesWallis, "bouncing bomb," used by the Royal Air Force to breach dams in Germany during World War 11. The Wallis bomb, Wyllie says, was essentially an explosive-filled sphere. It rotated on a horizontal axis normal to the
fore-and-aft axis of the Lan cashire bomber that carried it. The sphere rotated backward, or clockwise ifviewed from the left: of the aircraft. Thus, when the Lancashire launched the bomb, its periphery at the top REESE I was moving at 180° from the direction of the aircraft and, at the bottom, in the direction of the air craft. The result: Airflow increased at the top and decreased at the bottom of the bomb, which, therefore, experienced ver tical lift. Royal Navy officers called the phenomenon the Magnus effect. Research in Admiralty archives, Wyl lie reports, established that by the 18th century, and probably much earlier, peo ple knew that a smooth-bore cannon with a bend in it threw a spherical ball in a direction opposite to that of the bend. That is, a cannon if bent slightly left when viewedfromabovefiredto therightof its target. "Willie never did learn exactly when the expertsfiguredout that the ball's con tact with the right side of the bent bore created the curve-inducing spin. During the Napoleonic Wars, Wyllie goes on, if the sea were smooth, it was customary for ships to fight at long range not by elevating the muzzle of a cannon, which was difficult in any event, but to depress the muzzle and let the fired ball skip toward its target. He wondered whether people then realized that a drooping cannon would optimize longrange gunnery by firing a backward spin ning ball with lift. The Magnus effect was named for the German physicist and chemist H. G. Mag nus, according to the Encyclopedia Bri tannica. The effect is a special case of Bernoulli's theorem, and Magnus first experimented with it in 1853. The Bri tannica sums it up as "generation of a sidewise force on a spinning cylindrical or spherical solid immersed in a fluid (liquid or gas) when there is relative motion between the spinning body and the fluid. ... It is responsible for the curve ofa served tennis ball or a driven golf ball and affects the trajectory of a spinning artillery shell." Wyllie concurs: "The Magnus effect is useful in baseball—those chaps play ing rounders in their pajamas, in Admi ralty-speak—and in cricket where the effect of ball spin on hitting the ground is a second variable. It is of tremendous usefulness in golfwhen making approach shots with a lofted club and highly dele terious when slicing a drive."
©2001 Chevron Phillips Chemical Company LP.
10A
C & E N / J U N E A. 2 0 0 1
HTTP://PUBS.ACS.ORG/CEN
