Influence of Polymerization Temperature on Reactivity of 1- and 2.Vinyl Naphthalenes

Reactivity ratios relative to the copolymerizations of 1-vinyl naphthalene and 2-vinyl naphthalene with styrene have been determined at different specific temperatures. In the case of the system 1-vinyl naphthalene-styrene, the Arrhenius plot exhibits a curve when the temperature is above -50°C. This is explained by the depropagation contribution, The value of the enthalpy of polymerization calculated by using the Lowry relation is in satisfactory agreement with that obtained from calorimetric determinations. From activation enthalpies and entropies it appears that the selection of the two monomers by the cation is entropically controlled for 2-vinyl naphthalene and enthalpically controlled for 1-vinyl naphthalene.     

2‐Amino­thia­zole and 2‐amino­thiazolinone derivatives

The reaction of different substituted α‐cyano­oxiranes with thio­urea resulted in the formation of the 2‐amino­thia­zolinone derivative 2‐amino‐5‐(2,5‐di­methoxy­phenyl)‐1,3‐thia­zol‐4(5H)‐one, C₁₁H₁₂N₂O₃S, (I), and the 2‐amino­thia­zole derivative ethyl 2‐amino‐5‐(2,5‐di­methoxy­phenyl)‐1,3‐thia­zole‐4‐carboxyl­ate, C₁₄H₁₆N₂O₄S, (II). The geometries of the two crystallographically independent mol­ecules in (II) are nearly identical but mirror related. The crystal structures of both compounds contain two types of intermolecular hydrogen bonds.     

Sur la classification des automorphismes périodiques des C1-algèbres UHF

We obtain a complete classification up to conjugacy and up to outer conjugacy of finite tensor product type automorphisms of UHF C¹-algebras which are periodic of period N (N prime).     

Mechanism of the thickening reaction of polyester resins: Study on models

The thickening reaction of polyester resins is investigated using model compounds, diesters or polyesters of 1,2-propanediol and phthalic acid with dihydroxy or dicarboxy end groups. Soluble magnesium acetylacetonate was found to be an effective thickener, and for the first time it was possible to study a thickening reaction in homogeneous media (THF solutions). The results are compared with those obtained with MgO. The proposed mechanism supposes that the central step consists of the formation and the aggregation of magnesium carboxylates in ionic areas, with entanglement of attached polyester chains. This fits our experimental results better than the hypothesis of coordination of magnesium carboxylates by ester or hydroxyl groups of the chains^2–6 or than the hypothesis of the formation of linear high molecular weight compounds.^7–9     

Preparation de membranes echangeuses de cations par photogreffage d'ethers allyliques du poly (alcool vinylique). Etude de certaines de leurs proprietes—I: Preparation et etude de poly (alcool vinyliques) allyles

A new preparation of poly(vinyl alcohol) partially allylated (PAOV) is reported. The possible existence of crosslinking is explained but, under suitable conditions, it can be avoided. A detailed analysis of the infra red spectrum of PAOV shows that during allylation the structure of the original poly(vinyl alcohol) (PAV) is not changed. The compatibility of various monomers is studied.     

Study of the synthesis of poly(isobutylene-b-amide-11) by polycondensation of α,ω-dianhydride oligoisobutylene with α,ω-diamino oligoamide-11. I. Study of amine–anhydride and amide–anhydride reactions on low molecular weight models and on oligomers and polymers

The side reactions connected with the polycondensation of α,ω-diamino oligoamides and α,ω-dianhydride oligoisobutylenes are studied on low and high molecular weight models. Models for amine and anhydride end groups are dodecylamine and (2-dodecene-1-yl) succinic anhydride, respectively; their reaction is studied in the bulk (170°C) and in solution (142, 152, and 162°C); the products are analyzed by ¹H-, ¹³C-, and ¹H-¹³C-NMR and GPC. Some of these products and the junctions between the blocks are prepared independently. Models of amide groups in the chain are N-dodecyldodecanamide and N-dodecyloctadecanamide; their reaction with anhydride model results in cleavages with formation of imide groups. The results obtained from low molecular weight models are confirmed by studies on oligomers. They show unambiguous by that crosslinking which accompanies the block polycondensation originates from the reaction of amino-end groups with the intermediary acid groups resulting from the amine-anhydride reaction.     

Synthesis and preliminary biological evaluation of 5-fluoro-5,8-dideazaisoaminopterin

The new folate antagonist, 5-fluoro-5,8-dideazaisoaminopterin was synthesized in four steps beginning with 2,4-diamino-5-fluoroquinazoline. It was found to be a potent inhibitor of human dihydrofolate reductase. Against L1210 leukemia in mice, 5-fluoro-5,8-dideazaisoaminopterin was equiactive with methotrexate at approximately one half of the total dose employed.     

Synthesis of some novel halogenated 2,4-diaminoquinazolines

Three new 2,4-diaminoquinazolines, the 5,6-difluoro, 6,7-difluoro and 7,8-difluoro isomers were prepared by the reaction of the requisite trifluorobenzonitrile and guanidine carbonate. Surprisingly, 2,3,6-trifluorobenzonitriles gave 2,4-diamino-5,6-difluoroquinazoline exclusively as determined by high resolution nuclear magnetic resonance spectroscopy. On the other hand, 3-amino-2,6-difluorobenzonitrile on reaction with guanidine carbonate yielded only 5-fluoro-2,4,8-triaminoquinazoline. This compound was subsequently converted to 8-chloro-2,4-diamino-5-fluoroquinazoline using the Sandmeyer procedure. The nitration of 2,4-diamino-8-fluoroquinazoline occurred exclusively at position six yielding 2,4-diamino-8-fluoro-6-nitroquinazoline, which upon reduction with stannous chloride afforded 8-fluoro-2,4,6-triaminoquinazoline. In a similar fashion 7-fluoro-2,4-diaminoquinazoline underwent nitration at position six and was then reduced to give 7-fluoro-2,4,6-triaminoquinazoline. Finally, both of these triaminoquinazolines were converted to the 6-chloro derivatives under Sandmeyer conditions to yield 6-chloro-2,4-diamino-8-fluoroquinazoline and 6-chloro-2,4-diamino-7-fluoroquinazoline, respectively.     

Crown ethers as ligands for stereospecific polymerization by Ziegler–Natta catalysts

Some new TiCl₄/Crown ether complexes were synthesized and used as polymerization catalysts with AlEt₃ or AlEt₂Cl as cocatalyst for the stereospecific polymerization of 1,3-butadiene. As with most of the nucleophilic ligands the addition of crown ethers to Ziegler–Natta catalytic systems results in a decrease of the polymer conversion. But the Al/Ti molar ratio appears to be less critical for the complexed systems than for the uncomplexed ones. The presence of the crown ether in the surroundings of the catalytic sites presumably protects them from an excess of the organoaluminum cocatalyst. The side groups of the crown ether do not influence the microstructure of the polybutadiene obtained but they change the activity of the catalytic systems. Thus, the electron-donating effect of the macrocyclic ligands seems to be less important than the sterical effect due to the rigidity and to the hole size of the crown ether.