© 2000 Prentice Hall. All rights reserved.

Dr. Glaser's "Chemistry is in the News"
To Accompany Bruice, Organic Chemistry, 3/e.
Chapter 26. Synthetic Polymers.


For each of the following questions, please refer to the following article:
PAYING HOMAGE TO A NOBEL LAUREATE
by Joe Murray (Cox News Service, August 28, 1997)


Editorial Comments

What an inspiring story. The good man Murray tries to build some recognition for William Faulkner who lived in Rowan Oak in Oxford, Mississippi, and ends up with his hands glued together! And the glue worked very well apparently. "I did managed to super glue my hands together. Cops wouldn't have even needed the handcuffs," Murray writes.

Super glue, the superstar of modern adhesion, is cyanoacrylate and is sold under many names (SuperBonder, Permabond, Pronto, Black Max, Alpha Ace, Krazy Glue). The June 1993 issue of the Magazine of Fantasy and Science Fiction contained a long article on super glue which celebrated the advantages of super glue as follows: "Cyanoacrylate is an especially lovely and appealing glue, because it is (relatively) nontoxic, very fast-acting, extremely strong, needs no other mixer or catalyst, sticks with a gentle touch, and does not require any fancy industrial gizmos such as ovens, presses, vices, clamps, or autoclaves. Actually, cyanoacrylate does require a chemical trigger to cause it to set, but with amazing convenience, that trigger is the hydroxyl ion in common water. And under natural atmospheric conditions, a thin layer of water is naturally present on almost any surface one might want to glue."

"Super glue may make suturing obsolete," was the headline of a report by Richard Knox in the Boston Globe of May 22, 1997. Indeed, a new kind of super glue may make painful suturing obsolete in repairing common skin wounds. A Canadian study of 130 patients showed that the new surgical glue, called octylcyanoacrylate tissue adhesive, or OTA, was safe, effective, only one-third as likely to be associated with infection, and far less painful than stitches in closing wounds. The strength of the glue bond is only about 15 percent on the first day, compared to conventional sutures. But a week later there was no difference in wound strength, and only 1 to 5 percent of wounds came apart.

According to an editorial in the Journal of the American Medical Association (JAMA 1997, 277, 1559), the development of tissue adhesives has been stopped in the United States since 1985 because of carcinogenicity concerns (rats developed sarcoma after having their peritoneums implanted with a dose of adhesive one hundred times greater than the normal human dose). However, adhesives have been approved for use in Canada since 1975, and are also used widely in Europe, Israel, and the Far East. The editorial goes on to speculate: "In the United States, common lacerations are usually treated in emergency departments. Once adhesives become available for widespread use, primary care sites, clinics, dispensaries, and athletic venues will be able to treat many of these lacerations. It is not too far-fetched to speculate that these products might eventually become available for home use."



Pertinent Text References
Chapter 26. Synthetic Polymers.
Chapter 26.2 Sub-section on "Anionic Polymerization" in Section on "Chain-Growth Polymers".



Questions

Question 1: What is the structure of the monomer in "super glue"?

Answer 1: Methyl alpha-cyanoacrylate.



Question 2: What is the structure of the monomer of the "surgical super glue"?

Answer 2: Octyl alpha-cyanoacrylate.



Question 3: Explain the polymerization process of alkyl alpha-cyanoacrylate. What kinds of nucleophiles might initiate the polymerization.

Answer 3: Nucleophiles. Most usually the nucleophile would be water. But the nucleophile also can be the alcohol function on cellulose or any of the nucleophiles present in proteins.



Question 4: The anionic polymerization of alkyl alpha-cyanoacrylate yields a polymer with the backbone -[H2C-C(CN)(COOR)]n-, that is, every methylene group is connected to a C(CN)(COOR) group. Explain this regiochemistry.

Answer 4: Nucleophilic addition to H2C=C(CN)(COOR) occurs such that the anionic charge is located on the C atom that carries the electron-withdrawing groups CN and COOR.



Chemistry & Society.
When we think of glue, we almost almost always think of synthetic polymers. But there are of course many natural compounds that can serve as glue. Before the days of the self-adhesive stamp, the backsides of stamps used to have thin films of carbohydrate on them. And the of course, there are many natural compounds whose primary function is the provision of adhesion. Read the interesting article Integrins: The Molecular Glue of Life and talk with your peers about the ideas presented.