Propylammonium

Catalyst Cation. The logarithms of extraction constants for symmetrical tetra- -alkylammonium salts (log rise by ca 0.54 per added C atom. Although absolute numerical values for extraction coefficients are vastly different in various solvents and for various anions, this relation holds as a first approximation for most solvent—water combinations tested and for many anions. It is important to note, however, that the lipophilicity of phenyl and benzyl groups carrying ammonium salts is much lower than the number of C atoms might suggest. Benzyl is extracted between / -propyl and -butyl. The extraction constants of tetra- -butylammonium salts are about 140 times larger than the constants for tetra- -propylammonium salts of the same anion in the same solvent—water system. 

Tetra-n-propylammonium bromide [1941-30-6] M 266.3, m >280 (dec). Crystd from e thyl acetate/EtOH (9 1), acetone or MeOH. Dried at 110° under reduced pressure. 

Tetra-n-propylammonium iodide [631-40-3] M 313.3, m >280 (dec). Purified by crystn from EtOH, EtOH/diethyl ether (1 1), EtOH/water or aqueous acetone. Dried at 50° under vacuum. Stored over P2O5 in a vacuum desiccator. 

Tetra-n-propylammonium perchlorate [15780-02-6] M 285.8, m 239-241°. See tetrapropyl-ammonium perchlorate on p. 483 in Chapter 5. 

Tetra-n-propylammonium perruthenate (TPAP, tetrapropyl tetraoxoruthenate) [114615-82-6] M 351.4, m 160"(dec). It is a strong oxidant and may explode on heating. It can be washed with aq n-propanol, then H2O and dried over KOH in a vac. It is stable at room temp but best stored in a refrigerator. It is sol in CH2CI2 and MeCN. [Dengel et al. Transition Met Chem 10 98 1985 Griffith et al. J Chem Soc, Chem Commun 1625 1987.] Polymer supported reagent is available commercially. 

Tetramethylpiperidine tetra-n-Propylammonium perruthenate Tolyl Trityl... 

Several methods have been employed for the synthesis of TS-1.1"3 A typical method begins with the addition of tetraethylorthotitanate (TEOT) to tetra-ethylorthosilicate followed by the addition of a certain concentration of tetra-propylammonium hydroxide. The resulting mixture is stirred until clear, heated to remove alcohol, put into an autoclave, and heated to 175°C for 24 hours.4 Other methods use Ti(OBu)45,6 or TiF47 instead of TEOT. TS-2 contains a slightly larger cavity and is prepared in a similar manner.8,9... 

Figure 5.1 The alcogels shown are ORMOSIL doped with the ruthenium species tetra-M-propylammonium perruthenate (TPAP). Upon a mild heat treatment these materials become more active than TPAP in solution.

R. Ciriminna and M. Pagliaro, Tailoring the Catalytic Performance of Sol-Gel-Encapsulated Tetra-n-propylammonium Perruthenate (TPAP) in Aerobic Oxidation of Alcohols, Chem. Eur. J., 2003, 9, 5067. 

Tetra-rt-propylammonium periodate oxidation of the hydroxamic acids 215 (R = CH2OH, CH20Me, CH2NHPI1 or CC Me), derived from L-proline, generates nitroso compounds 216, which, in the presence of cyclohexadiene, give mixtures of diastereomeric cycloadducts 217 in 79-89% yields and 26-68% de values (equation 115)109. 

Tetra-n-propylammonium perruthenate also oxidizes sulphides to sulphones [45]. Yields are generally high for dialkyl sulphides and alkyl aryl sulphides, but lower for diaryl sulphides. 

Secondary nitro compounds are oxidized to the corresponding ketones in moderate yields by a catalytic amount of tetra-n-propylammonium perruthenate in the presence of N-methyImorpholine-A-oxide and a silver salt [46]. Oxidation with a stoichiometric amount of the ammonium perruthenate has also been reported [47]. 

Secondary amines and A /V-dialkylhydroxylamines are rapidly oxidized by tetra-rt-propylammonium perruthenate to imines and nitrones, respectively (Scheme 10.5) [48,49]. Chiral centres are unaffected during the oxidation. 

Tetraethylammonium Tetra-H"propylammonium Tet ra-H butylammon ium Methyltri-H butylammonium... 

Reductive y-lactone ring opening, with concomitant desilylation at the tertiary position by LiAlH4, gave triol 17 in 80% yield. Finally, acetonide formation followed by oxidation with tetra-n-propylammonium perruthenate/A-methylmorpholine / /-oxide oxidation, led to the target aldehyde 19 in 80% overall yield. 

After desilylation with tetra-n-butylammonium fluoride and oxidation with tetra-n-propylammonium perruthenate the dialdehyde 23 was obtained in 32% overall yield. 

The next important steps to the key intermediate 30 are outlined in Scheme 13.6.5. Monoacetylation of 24 followed by oxidation with tetra-n-propylammonium perruthenateW-methylmorpholine A -oxide, afforded regioselectively in 88% overall yield, ketoacetate 21. ... 

Unambigous structural confirmation was obtained by converting 53a to diol carbonate 56, which was independently synthesised from baccatin III. Selective deprotection of 53a with TBAF gave alcohol 54, which was oxidised with tetra-n-propylammonium perruthenate/)V-methylmorpholine A -oxide (CH2CI2, molecular sieves, 25 °C, 1.5 h) to ketone 55 in 86% overall yield from 53a. Deprotection (HF, pyridine, CH3CN, 96%) of gave diol carbonate 56, identical to the compound prepared from baccatin III. 

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