Task specific

The certainty factor approach has been among the more popular rule-based approaches to uncertainty. However, although it is easy to apply given the individual CFs, acquiring the raw CFs from the experts is often quite difficult. Further, although the formulas for CF combination are mathematically appealing, they often have no relation to the ways in which experts combine evidence to arrive at conclusions. Some of the task-specific approaches discussed later address uncertainty combination in a more intuitive way (35). 

D. Task-specific hazard analyses must lead to the development of written standard operating procedures (SOPs) that specify the controls necessary to safely perform each task. Detailed hazard analyses conducted for each site task and operation provide the basis for developing SOPs to protect employees from safety and health hazards. Written SOPs provide a mechanism for informing employees of procedures that ensure their safety and for enabling management to enforce hazard control procedures. 

Requirements for written safety and health SOPs are found in paragraphs (b)(4)(I) of the HAZWOPER standard. None of the sites audited had developed comprehensive, site-specific SOPs that specify the controls necessary to complete each task. The contractor s SSAHP at Site B did discuss generic task-related hazards and SOPs however, the task-specific SOPs lacked detail. Eor example, the SOPs did not specifically identify the site locations where hazards were likely to occur, nor did they specify the appropriate types of controls. 

The SSAHP developed by the Site G contractor did not indicate that the contractors routinely conducted job- or task-specific hazard analyses. In addition, the SSAHP did not specify that PPE selection for jobs and tasks must be based on the analysis of the health hazards associated with each job. Eurthermore, the SSAHP contained no procedures for objectively determining the effectiveness of decontamination of personnel or equipment. The decontamination program required incineration of all materials that could not be readily decontaminated such materials were placed in labeled disposal containers. The program, however, did... 

Is PPE selected based on an evaluation of performance characteristics of the PPE relative to requirements and limitations of the site, task-specific conditions and duration, and hazards and potential hazards identified ... 

The second element of general importance in the synthesis of a task-specific ionic liquid is the source of the functional group that is to be incorporated. Key to success here is the identification of a substrate containing two functional groups with different reactivities, one of which allows the attachment of the substrate to the core, and the other of which either is the functional group of interest or is modifiable to the group of interest. Functionalized alkyl halides are commonly used in this capacity, although the triflate esters of functionalized alcohols work as well. 

Although the first ionic liquid expressly categorized as being task-specific featured the incorporation of the function within the cation core, subsequent research has focused on the incorporation of functionality into a branch appended to the cation [11]. In this fashion, a number of task-specific ionic liquids built up from 1-methyl- and 1-butylimidazole have been prepared, produced by means of the reaction between these imidazoles and haloalkanes also incorporating a desired functional group (Scheme 2.3-1). Bazureau has used this approach to prepare imida-... 

Scheme 2.3-1 General synthesis of task-specific ionic liquids from l-alkylimidazoles.

Scheme 2.3-4 Synthesis of a cheiating task-specific ionic iiquid and its utiiization for metai...

Figure 2.3-5 Imidazolium-based task-specific ionic iiquids with cation-appended fiuorous taiis.

Apart from being employed solely as solvents, ILs can also be used as reagent carriers (TSlLs, task-specific ionic liquids). An efficient system that uses ILs as solvents and anchoring/acylating reagents for the CAL B-catalyzed separation of racemic alcohols is shown in Scheme 5.17 [69]. 

Visser AE, Swatloski RP, Reichert WM, Mayton R, Sheff S, Wierzbicki A, Davis JH, Rogers RD (2001) Task-specific ionic liquids for the extraction of metal ions from aqueous solutions. Chem Commun 1 135-136... 

Visser, A.E., Swatloski, R.P., Reichert, W.M. et al. (2001) Task-Specific Ionic Liquids for the Extraction of Metal Ions from Aqueous Solutions. Chemical Communications, 1, 135-136. 

The factor k (the transfer factor) was defined as a crop- and task-specific factor and is defined as the slope of the line that fits dermal exposure levels (g/hr) and corresponding levels of DFR (g/m2) on the crop (i.e., the regression coefficient of DFR). The DFR, according to the procedures described by Iwata et al. (1977), was considered to be a good estimate of source strength for re-entry exposure. 

Using a similar protocol, Loupy and coworkers have reported the synthesis of chiral ionic liquids based on (ll ,2S)-(-)-ephedrinium salts under microwave irradiation conditions (Scheme 4.21a) [75]. Importantly, the authors were also able to demonstrate that the desired hexafluorophosphate salts could be prepared in a one-pot protocol by in situ anion-exchange metathesis (Scheme 4.21b). The synthesis and transformation of so-called task-specific ionic liquids is discussed in more detail in Section 7.4. 

The second group of recently developed ionic liquids is often referred to as task specific ionic liquids in the literature [15]. These ionic liquids are designed and optimised for the best performance in high-value-added applications. Functionalised [16], fluorinated [17], deuterated [18] and chiral ionic liquids [19] are expected to play a future role as special solvents for sophisticated synthetic applications, analytical tools (stationary or mobile phases for chromatography, matrixes for MS etc.), sensors and special electrolytes. 

Figure 7.3. Examples of task specific ionic liquids...

In recent times, the development of new ionic liquids has made great progress. Important developments include a range of new halogen-free ionic liquids (e.g., benzenesulfonates [13], toluenesulfonates, alkylsulfates [14], hydro-gensulfate [15, 16], dicyanamides [17], thiocyanates [18], etc.), as well as functionalized (task-specific) [19-23], fluorinated [24], deuterated [25] and chiral ionic liquids [26-30]. 

Ionic liquids have also been applied in transfer hydrogenation. Ohta et al. [110] examined the transfer hydrogenation of acetophenone derivatives with a formic acid-triethylamine azeotropic mixture in the ionic liquids [BMIM][PF6] and [BMIM][BF4]. These authors compared the TsDPEN-coordinated Ru(II) complexes (9, Fig. 41.11) with the ionic catalyst synthesized with the task-specific ionic liquid (10, Fig. 41.11) as ligand in the presence of [RuCl2(benzene)]2. The enantioselectivities of the catalyst immobilized by the task-specific ionic liquid 10 in [BMIM][PF6] were comparable with those of the TsDPEN-coordinated Ru(II) catalyst 9, and the loss of activities occurred one cycle later than with catalyst 9. 

Fig. 41.11 R u-complex and task-specific ionic liquid for the hydrogenation of acetophenone derivatives.

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