Sulfones can react as nucleophiles or electrophiles Base *SO ? C G H,,
SO ? C 6 H,
AICI Ether
In basic medium, a proton is abstracted from the carbon atom adjacent to the sulfone function. The resulting carbanion attacks the alkyl bromide, yielding a second sulfone. This product, in the presence of a Lewis acid (aluminum chloride), loses the phenylsulfone group, producing a carbocation that attacks the phenyl ring to give the bicyclic molecule
This methodology is not limited to cyclizations, however. Trost and Ghadiri have carried out intermolecular reactions as well. Because this "duality of behavior" is a general property of sulfones, Trost says, it likely will enable chemists to construct complicated molecules using fewer steps. And, he adds, sulfones are a new class of compounds that can take part in Friedel-Crafts alkylations. "We're ex ceedingly excited about the pros pects" for using sulfones in electrophilic reactions, Trost remarks. G
EDUCATION
Computer use in undergraduate chemistry marks 25th anniversary This autumn marks the 25th anni versary of computer use for under graduate chemistry instruction. Chemistry professor Peter Lykos of Illinois Institute oi Technology, Chicago, notes that in November 1959, he assigned his physical chem istry students the task oi writing and executing a program to per form a least-squares fit of their ben zene vapor pressure-tempe rature data. This was the first time comput ers had been used in any under graduate chemistrv class. The mag nitude of the task shows how far computer applications in such uses have come. The computer available then was not a micro or even a mini, but one of Sperry Rand's Univac 1105 main frames, based on vacuum tubes. None of the higher-level languages were available, and students had to learn the rudiments of assembly lan guage programing, itself just one step up from binary machine code. The machine's memory was a mag netic drum. Students entered pro grams and data on strips of punched paper tape. The output was carried to the printer on magnetic tape. To write their programs, the stu dents reserved the first 1000 address es in the memory for data. They also used 10 out of the 50 available machine instructions for simple arithmetic operations and switch ing data among addresses in memory. Address location numbers took the place of line numbers, and the
machine searched through each in ished, the operator fed the resulting sequence, beginning with 05775 for magnetic tape into a printer and the main program. Students spelled handed the results to the student. That physical chemistry class out each operation in detail, specify ing movement of intermediate re helped to shape the future career in sults into and out of address loca chemistry of one of the students, Robert E. Wyatt. He is now professor tions. Lykos already had a subroutine of theoretical chemistry at the Uni that would take the natural loga versity of Texas, Austin. "The whole rithm of a n u m b e r to evaluate thing felt very strange to us," he /;/ Ρ ~ Λ - B/T for the benzene data. says, remembering his experience. Students were allowed punched pa "We had heard of computers, oi per tapes of this, which inserted course, but we had never seen or this subroutine into address loca touched one. The whole idea of tions that followed the main pro doing a physical chemistry laborato ry experiment on a computer seemed gram. Over and above the time needed very, very strange and alien." From the first step, difficulties for experimental Ρ - Τ data deter minations, the computer laboratory were encountered in writing and took six hours. For three morning running the program. "We all made hours, students learned concepts of a lot of dumb errors," Wyatt says. memory and address locations, ma "We didn't even know how to chine instructions, and construction punch in the program. We sensed ot loops and subroutines, aided by something important was happen a sample program that evaluated ing to us but had no idea which / (Λ ) = v2i/ - 3 + /;/ -. Hach class of 20 direction to walk in. It was like labored as a group at the blackboard trying to get through a jungle, to compose the least-squares pro knowing where we wanted to get gram. Then they punched their data to basically, but having no idea what and program onto paper tape with path to follow." Most students took not one but a typewriter. In the afternoon, students went many trips back to the computer on a field trip to the computer cen center that afternoon. "Finally, ev ter of 11T Research Institute on eryone got the program to work," campus. There, an operator loaded Wyatt says. "It was a wonderful a program into the Univac that thing to see numbers being printed would teach it how to read paper out on a sheet oi paper and realizing, tapes. He ran the three paper tapes 'My gosh, those are actually the cor from each student through a reader. rect numbers!' " Stephen Stinwii, New York When each computation was fin December 3. 1984 C&EN
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