Document Z4b8edoGmvXN2RxmEjEVj84Yp

^^IIBirtAirro Chemical Company ' ' At Dayton, Ohio H. L. Hubbard-Ree. 2-31. R. L. Janklna R. A. Ruehrweln Datf November 11, 195^ To A. M. Ellenburg At ST. LOUIS Reference Your letter Nov. 2, 19: Subject AROCLOR STABILITY We*are happy to say chat the Aroclor report has and will be issued as soon as mimeographing is comi Copies are being 3ent to you and H. L. Hubbard. Sinl will be a few days before you receive your copies, we oan summarize some of our conclusions. The principle conclusion is that the loss of electrical resistivity is caused by the degradation of the chlorinated biphenyl molecule itself arising from the homolytic cleavage of a carbon-chlorine bond to give a free chlorine atom and an aromatic or aromatic substituted free radical. The free chlorine atom may either extract a hydrogen atom to produo* hydrogen chloride or ado onto the aromatic ring to produce an alicyclic unsaturated complex. Subsequent reactione can produce a compound bearing a chlorine on an aliphatic carbon which: is capable of resonance stabilization and the formation of stacle carbonlum ions. We found that Increased ohlorlnatlon reduces the possibility of resonance stabilization by blocking the ortho-position. Thus the higher degree of chlorination, the more stable is the Aroclor to photo or thermal degradation. Aroclor 123^ is much more atable than 1242. From the proposed mechanism of degradation, the loss.of electrical resistivity is caused by the formation of (1) hydrogen chloride and (2) a chlorine addition compound which is capable of forming stable carbonlum ions. Both of these products arise from the reactions Involving the chlorine atom. Stabilizers must react with the chlorine atoms as they are formed if the resistivity level i3 to be maintained. Stabilizers which act as hydrogen chloride scavengers alone can only remove a small portion of the conducting material. Since Aroclors will degrade pnotochemlcally regardless of purity and no purification process will eliminate this instability, the addition of stabilizers remains as the only solution. We found that tetraethyl lead was the most efflolent stabilizer, however, this compound produced s slight turbidity during the Aroclor degradation. We attributed tils hast to be due to the Insolubility of the trlethyl lead chloride formed after reaction with chlorine atoms. We are looking into the possibility of other lead compounds whose chloride should be more soluble in Aroclor. We have been in contact with th# Ethyl Corp. for suitable lead compounds for trial. d in io 0545378 HARTOLDMON0005038 A. K. Ellenburg -2 November 11, 1951* ' We would like to study more quantitatively the degradation process to learr. what wave lengths are effective and the quantum yields. These studies could be done with chloro benzene as a prototype. We would appreciate any comments you may have on the report. Best 2'egards, A. S. Kenyon Jes 0545379 i9 .. * HARTOLDMONOOQ5039