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CHEMISTRY 401 and 80 grams (0.27 mole) of antimony pentachloride were placed in the autoclave: the mixture was heated at 340°C. for 48 hours with constant agitation. The autoclave was then cooled to room temperature, and liquid products were decanted from solid antimony salts remaining in the reaction vessel. The fluorinated material was washed with dilute hydrochloric acid and steamdistilled. Two hundred grams of crude product were obtained, dried, and rectified. Three separate fractions were obtained and identified as 45 grams of l-(heptafluoroisopropyl)-4-(trifluoromethyl)benzene, 83 grams of l-(chlorohexafluoroisopropyl)-4-(trifiuoromethyl)benzene, and 35 grams of l-(dichloropentafluoroisopropyl)-4-(trifiuoromethyl)benzene. Conversion to 1-(heptafluoroisopropvl)-4-(trifluoromethyl)benzene was 15% and the yield 50%. 2. Five hundred seventy-four grams of a mixture composed of 279 grams (1.0 mole) of (dichloropentafluoroisopropyl)benzene, 295 grams (1.0 mole) of (trichlorotetrafluoroisopropyl) benzene, 400 grams (2.2 moles) of powdered antimony trifluoride, and 90 grams (0.3 mole) of antimony pentachloride were placed in the autoclave. The reaction was heated at 330°C. for 30 hours and then cooled to room temperature, and the liquid products were decanted. The fluorinated product was treated as described, 219 grams of product being obtained. Rectification yielded three fractions: 49 grams of (heptafluoroisopropyl)benzene, 79 grams of (chiorohcxafluoroisopropyl)benzene, and 56 grams of (dichloropentafluoroisopropyl)benzene. Conversion to (heptafluoroisopropyl)benzene was 10%, and to (chlorohexafluoroisopropyl)benzene 15%. The yield was 35%.The compounds were purified by rectification in a Podbivlniak Hyper-Cal column. The physical constants arid halogen analyses are given in Table I.

No abstract

Formal methods such as CSP (Communicating Sequential Processes) are widely used for reasoning about concurrency, communication, safety and liveness issues. Some of these models have been extended to permit reasoning about real-time constraints. Yet, the research in formal specification and verification of complex systems has often ignored the specification of stochastic properties of the system under study. We are developing methods and tools to permit stochastic analyses of CSP-based specifications. Our basic objective is to evaluate candidate design specifications by converting formal systems descriptions into the information needed for analysis. In doing so, we translate a CSP-based specification into a Petri net which is analyzed to predict system behavior in terms of reliability and performability as a function of observable parameters (e.g., topology, fault-tolerance, deadlines, communications and failure categories).This process can give insight into further refinements of the original specification (i.e., identify potential failure processes and recovery actions). Relating the parameters needed for performability analysis to user level specifications is essential for realizing systems that meet user needs in terms of cost, functionality, and other non-functional requirements.An example translation is given (in addition, some general examples of CSP -> Petri net translations can be viewed in Appendix A). Based on this translation, we report both the discrete and continuous time Markovian analysis which provides reliability predictions for the candidate specification. The term "CSP-based" is used here to distinguish between the notation of Hoare's original CSP and our textual representations which are similar to occum. Our CSP-based grammar does not restrict consideration of the properties of CSP (traces, refusal sets, livelock, etc.), but we are not considering those properties. We are only interested that the structural properties are preserved. We define performability as a measure of the system's ability in meeting deadlines, in the presence of failures and variance in task execution times.