TBAB

From a tetrazole TrCl, CH2CI2, TBAB, NaOH, H207 ... 

Methyl-l//-l,5-benzodiazepin-2(3//)-one (17.4g, 0.1 mol) and an alkyl halide (0.1 mol) in benzene (70 mL) was stirred at 50 C and treated with 50% aq NaOII (30 mL, 0.15 mol) and a catalytic amount of TBAB. Stirring at 50CC was continued for 1 h and the mixture was cooled and separated. The organic phase was washed with H20, dried (MgS04) and evaporated under reduced pressure, leaving the product. 

In 2003, Van der Fycken pubhshed a copper- and palladiirm-free microwave-assisted Sonogashira-type protocol in water with phenylacetylene as the alkyne (Scheme 51) [69]. The phase-transfer agent TBAB was used to facilitate... 

The same group also described the rapid cyanation of aryl iodides in water using CuCN (Scheme 72) [82]. The addition of the phase-transfer agent TBAB was crucial for the reactions otherwise, no reaction occurred. CuCN can also be generated in situ from NaCN and Cul (Scheme 72). While aryl iodides gave good results, the yield obtained with 3-pyridinyl iodide was poor. 

Benzofurans have been prepared by microwave-accelerated cyclocondensation of differently substituted salicylaldehydes 182 with esters of chloroacetic acid 183 in the presence of K2CO3 (used as the solid support) and tetrabutyl-ammonium bromide (TBAB) as phase transfer catalyst [120]. This method seemed general regarding the variations at the benzene ring and the nature of the ester moiety (Scheme 66). 

TBACl > TPACl, while in the case of bromine as anion the reverse was taking place according to the alkyl chain length i.e. TMAB > TBAB. Both the hi activity and the short induction period obtained by simply adding QASs are the best level comparing to reported results so far. 

FIG. 8 Capillary wave frequency dependence on the concentrations of TBAB and CgH50Na. 

The equilibrium concentration of CfiH50Na above which the adsorption was saturated depends on the TBAB concentration. The relationship between the TBAB concentration and the CgH50Na concentration is shown in Fig. 9. These equilibrium concentrations were used to analyze the reaction between the two reactants, assuming that at these concentrations the reaction proceeds without residue and deficiency. The ratio of the TBAB concentration to the C6H50Na concentration deviates from the line for 1 1 below 50 mM. When the TBAB concentration is above 50 mM, the ratio of the TBAB concentration to the C6H50Na concentration at the water-nitrobenzene interface is unity. On the other hand, when the TBAB concentration is below 50 mM, the ratio of the CgHsONa concentration to the TBAB concentration is more than unity. 

In general, the formation of an ion pair TBA+CgHsO occurs by the reaction between one TBAB molecule and one C HsONa molecule in the water phase. Thus, the ratio of the CgHsONa concentration to the TBAB concentration should be unity if the reaction has occurred in the water phase. The behavior above 50 mM can be simply explained by the reaction in the water phase between one TBAB molecule and one CgHsONa molecule. However, the behavior below 50 mM cannot be explained by this... 

FIG. 9 Relationship between the TBAB and CgHsONa concentrations in equilibrium. 

A palladium catalyst with a less electron-rich ligand, 2,2-dipyridyl-methylamine-based palladium complexes (4.2), is effective for coupling of aryl iodides or bromides with terminal alkynes in the presence of pyrrolidine and tetrabutylammonium acetate (TBAB) at 100°C in water.37 However, the reactions were shown to be faster in NMP solvent than in water under the reaction conditions. Palladium-phosphinous acid (POPd) was also reported as an effective catalyst for the Sonogashira cross-coupling reaction of aryl alkynes with aryl iodides, bromides, or chlorides in water (Eq. 4.18).38... 

Table 1 Time dependent performance in direct carbonylation of phenol using lead based catalysts with varying palladium sources (0.25 mM Pd, 12 eq. PbO, 5.6 eq. Ce(acac)3, 400 eq. TBAB).

Figure 2 Pd TON response surface of for PbO-TBAB (a) and PbO-TiO(acac)2-TBAB (b) co-catalysts.

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