H-butylammonium chloride

In a typical run, 5 mmoles of fert-butylamine in chloroform reacted with 4.1 mmoles of ozone in an ozone-nitrogen stream at about —60°C. to give 0.9 mmole (18%) of 2-methyl-2-nitropropane (XI), 0.9 mmole (18% ) of tert-h iiy isocyanate (XVI), and 3.0 mmoles (60% ) of tert-butylammonium chloride (XIV). In a separate but similar run, 3.5 mmoles of molecular oxygen were determined as a product. Under the conditions of the reaction no significant reaction occurred between ferf-butylamine and chloroform in the absence of ozone or between ozone and chloroform in the absence of the amine. 

Typical procedure. 1,2,2,2-Tetrachloroethyl chloroformate 103 [58] Freshly distilled chloral (4.4 g, 0.030 mol) was added (over 30 min) to a stirred refluxing solution (dry-ice Dewar condenser) of benzyl tri-n-butylammonium chloride (BTBAC) (10 g, 0.032 mol) in phosgene (for a safe source, see Chapter 7) (60 mL). After 1 h, the excess phosgene was removed through a series of five bubble traps (empty, H2SO4, empty, aqueous NaOH, NH4OH to hood exhaust) with the aid of an aspirator, and the 1,2,2,2-tetrachloroethyl chloroformate was isolated by distillation bp 76-79 °C/19 Torr, 47.7 g (65% yield). Note Unless 1,2,2,2-tetrachloroethyl chloroformate is completely free from the catalyst, it slowly reverts to the reactants. 

The large-scale synthesis of a-chloroethyl chloroformate (ACE-Q) by the above method (stirring acetaldehyde with 1.1 equiv. of neat pho ene for 1 h in the presence of 3.0% benzyl tri-n-butylammonium chloride (BTBAC), giving an isolated yield of 96%) has a particular value since its ethanolysis product, a-chloroethyl ethyl carbonate, is a commercial alkylating agent used to mask carboxyls in penicillins and cephalosporins. 

Malhotra and Datta [89] impregnated Nation membranes with HP As by imbibing them in solutions of a HPA, HPW in acetic acid or tetra- -butylammonium chloride. Preliminary results showed a dramatic improvement in fuel cell output at elevated temperatures, e.g., at 110°C, the fuel cell provides a power density of 465 mW/cm at 0.5 V which is comparable to the typical performance obtained with conventional PEM fuel cells at 80°C. Membranes have been cast from HPA impregnated Nafion using Iraig annealing times, 4 h, at 130-170°C to cross-Unk and immobilize the HP As in the membrane [91]. 

The complete elimination of functional groups is often an undesirable side reaction in organic synthesis, but on the other hand it is a possibility for the recycling of environmentally harmful compounds, for example phenols and haloarenes such as polychlorinated dibenzodioxins (PCDDs or dioxins ). For example, aryl chlorides can be effectively dechlorinated with Pd(0) NPs in tetra-butylammonium salts with almost quantitative conversions also after 19 runs (entry H, Table 1.4) [96]. On the other hand, a C-0 bond cleavage reaction also seems suitable for the fragmentation of sugar-based biomass such as cellulose or cello-biose in that way, sugar monomers and bioalcohol can be derived from renewable resources (entry F, Table 1.4) [164]. 

It is noteworthy that benzyltriethylammonium chloride is a slightly better catalyst than the more lipophilic Aliquat or tetra-n-butylammonium salts (Table 5.2). These observations obviously point to a mechanism in which deprotonation of the amine is not a key catalysed step. As an extension of the known ability of quaternary ammonium halides to form complex ion-pairs with halogen acids in dichloromethane [8], it has been proposed that a hydrogen-bonded ion-pair is formed between the catalyst and the amine of the type [Q+X—H-NRAr] [5]. Subsequent alkylation of this ion-pair, followed by release of the cationic alkylated species, ArRR NH4, from the ion-pair and its deprotonation at the phase boundary is compatible with all of the observed facts. 

Materials. CEVE and 4-nitrophenyl vinyl ether (VNP) were synthesized and purified as reported earlier (12,13), respectively. 2-(4-Nitrophenoxy)ethyl vinyl ether (NPVE) (m.p. 72-73°C) was prepared by reacting of potassium 4-nitrophenoxide (PNP) (142 g 0.8 mol) and CVE (842 g 7.9 mol) using tetra-n-butylammonium bromide (TBAB) (4.0 g 12 mmol) as a phase transfer catalyst at the boiling temperature of CVE for 12 h. The potassium chloride produced was filtered off, the filtrate washed with water, excess CVE evaporated, and then the crude product was recrystallized twice from n-hexane. (Yield 61.7%. IR (KBr) 1630 (C=C), 1520 (-N02), and 1340 cm-1 (-N02).) Elemental analysis on the product provided the following data Calculated for C10HnNO4 C, 57.40%, H, 5.30%, N, 6.69%. Found C, 57.49%, H, 5.3%, N, 6.72%. 

Since calotropagenine, the aglycone of uscharidine, is accessible only with difficulty, model experiments have been carried out with the more readily available cholestan-2oc,3P-diol 21. On Ag2C03-mediated reaction with actino-spectosyl chloride 18 two isomers formed smoothly in an approximate 3 1 ratio, of which the major one - as evidenced by H- and 13C-NMR data, corroborated by NOE experiments - proved to be the "unnatural" anellation product 23. The minor product 22, however, could be readily debenzoylated by treatment with butylammonium acetate in aqueous acetonitrile to afford the uscharidine analog 24 albeit in modest yield (46), yet crystalline form so that its linkage geometry could be secured by an X-ray structure analysis (47). 

In the first synthesis of the potent antitumor agent may famine 131) by Corey et al. [75], linear amino acid 129 was first converted to the soluble tetra-n-butylammonium salt and then slowly added to a solution of excess mesitylene-sulfonyl chloride and diisopropylethylamine in benzene at 40 °C for 28 h to afford macrolactam 130 in 71% yield (Scheme 44). 

Conditions a) SnC, NaNs b) NaCN, MeOH c) polystyrene MMT-CI resin, DMAP, pyridine d) t-butyidimethylsilyl chloride, Imidazole e) PMea f) diisopropylethylamlne g) Set A amine building blocks, diisopropylethylamlne, 0 °C to rt h) Set B amine building blocks, diisopropylethylamlne, 75-80 °C i) 1M tetra-n-butylammonium fluoride in THF j) 2% trifluoroacetic acid in 1,2-dichloroethane, 1 min... 

Other suitable reaction solvents are aqueous tetrahydrofiiran, 1,2-diraethoxyethane or acetonitrile [28]. The same result was obtained by the method G, whereas 4-nitro-chlorobenzene was also coupled, in almost quantitative yield, within 2 h at 100 °C, or 87 h at room temperature. However, in the presence of tetra-n-butylammonium bromide (5 mol%), a soluble source of bromide anions, the SM reactions of aryl bromides have been effected in ethanol at room temperature in the presence of palladium(II) acetate or chloride (2 mol%) and potassium phosphate (2 eq.) as the base, even under exposure to air [55]. Palladium salts are reduced in situ with arylboronic acids to form catalytically active nano-sized palladium clusters (2-5 nm). The latter are stabilized by adsorbtion of one-layer bromide ions at the surface of each palladium-particle. Otherwise, the unstable nano-sized palladium-clusters are aggregated to the micro-sized catalytically inactive palladium black. In this manner, 2-bromonaphthalene (268) was reacted with 2-methoxyphenylboronic acid (269) to fiimish the biaryl 270 in 98% yield [55], respectively. Scheme 17. 

CsF added to tetra- -butylammonium bromide or Aliquat 336, the mixture stirred for 5 min, n-octyl bromide added, stirring continued for 5 min, and allowed to react for 40 h - n-octyl fluoride. Y 77%. Work-up is easy and reagents readily available yields are high from satd. chlorides and bromides (incl. benzylic), but aromatic bromides were more resistant. F.e. and with tetra-n-butylammonium fluoride, also from tosyla-tes, and comparison with other heterogeneous methods s. G. Bram et al., Synth. Commun. 18, 1661-7 (1988) review of solid-liq. phase transfer catalysis without solvent s. Bull. Soc. Chim. France 1989, 247-51. 

A mixture of 1-chloroethyl phenyl carbonate, 1.2 eqs. trimethylsilyl bromide, and a little tetra-n-butylammonium bromide heated at 90° for 24 h with continuous removal of trimethylsilyl chloride followed by excess reagent - 1-bromoethyl phenyl carbonate. Y 91%. The equilibrium is driven to the product by continuous removal of the chlorosilane. F.e., also with HBr or acetyl bromide, s. J.-P. Senet et al., Synth. Commun. 18, 1531-6 (1988). 

A mixture of di(/-amyl)thiophosphinic acid, K2CO3, a little tetra-n-butylammonium bromide, and n-butyl bromide heated at 60° for 0.5 h product. Y 97%. Bulky alkyl bromides gave lower yields, while alkyl chlorides were unreactive. F.e.s. C. Yuan et al.. Synthesis 1989, 48-9. 

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