A simple yet effective high temperature furnace for heating crystals or powder specimens for neutron diffraction studies on a θ/2θ diffractometer is described. The furnace can maintain samples at temperatures up to 1573 K, in air, with a stability of ± 4 K for periods of many hours. Specimen temperature is uniform within 12 K, or much less with the use of a silica sleeve.

This paper describes methods by which strong vacuum-tight bonds between gold and alumina can be fabricated in an air atmosphere. Temperature was found to be a sensitive factor in bond formation; the higher the temperature, the stronger the bond, provided that the temperature remained below the melting point of gold. Intimate contact between the bonding gold and alumina surfaces during formation of the bond was also an important consideration. This was achieved by using an optically flat and polished ceramic surface and applying a low pressure of about 1 MPa to the bonding couple. Further enhancement of the contact can be achieved by depositing an additional thin layer of gold onto the ceramic surface by evaporation or by other means, and by thorough cleaning by high temperature heat treatment prior to bonding. Good bonding occurs in the range of 1 to 100 h. Bond strengths as high as 80 MPa were achieved.

A high-temperature neutron diffraction apparatus has been used to study a section of the zirconia-scandia system; the purpose was to determine whether this technique can be generally applied to phase equilibria studies. The structure of the tetragonal form of zirconia at 1200°C has been confirmed, and the parameters obtained were z(4d) = 0.188 ± 0.002, B0 = 2.50Å2, BZr = 0.80 Å2, and R = 0.045. The effect of substituting scandia into the tetragonal zirconia structure was studied and the transformation of the ordered low-temperature β-phase to a grossly nonstoichiometric fluorite phase was also observed.

Partial rate factors for protodesilylation of some aromatic compounds Me3Si·C6H4X in methanol–perchloric acid at 50 °C have been determined as: (X =)2-OH, 3720; 2-SH, 4·42; 4-SH, 11·3; 2-SMe, 18·4; 4-SMe, 65·2; 2-CH2Ph, 3·75, and for detritiation of the 2-position of thioanisole in trifluoroacetic acid at 70 °C, 21,500. The relative reactivity of thioanisole and thiophenol is in the inductive order, i.e., SMe activates more than SH in contrast to the results for the oxygen and carbon analogues and this is interpreted as constituting impressive evidence for hyperconjugation in the latter compounds. The ortho:para ratio decreases along the series CH2Y, OY, SY, (where Y = H, Me, or Ph) and ZMe, ZH, ZPh (where Z = CH2, O, or S) apparently through the increasing importance of the inductive effect at the ortho-position; the previously observed low reactivity of the 2-position of diphenyl sulphide in protodesilylation is confirmed and shown not to be anomalous.Application of the Yukawa–Tsuno equation to the desilylation data yields a value for σ+4-SH of –0·365; a value for ƒ4MeO of 1270 is argued to be more accurate than the literature value of 1520.Metallation of diphenyl sulphide produces a mixture of ortho- and meta-derivatives, not merely the former as stated in the literature, and this parallels a recent report on metallation of thiophenetole. The reported rearrangement of 4-LiC6H4·S·SiMe3 to 4-SiMe3·C6H4·SLi is shown to be almost certainly an intermolecular reaction.

Chemischer Informationsdienst. Organische ChemieVolume 2, Issue 42 Preparative Organic Chemistry ChemInform Abstract: ELEKTROPHILE AROMATISCHE SUBSTITUTION 6. MITT. PROTODESILYLIERUNG UND PROTODETRITIIERUNG VON O UND S ENTHALTENDEN AROMATISCHEN VERBINDUNGEN UND VERBINDUNGEN DES DIPHENYLMETHANS, BEWEIS FUER HYPERKONJUGATION F. P. BAILEY, F. P. BAILEYSearch for more papers by this authorR. TAYLOR, R. TAYLORSearch for more papers by this author F. P. BAILEY, F. P. BAILEYSearch for more papers by this authorR. TAYLOR, R. TAYLORSearch for more papers by this author First published: October 19, 1971 https://doi.org/10.1002/chin.197142199Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume2, Issue42October 19, 1971 RelatedInformation