Teabags

Mention may also be made of an application in which careful control of polymer morphology has led to the production of novel materials. By treatment of solutions of high-density polyethylene, products are obtained with a celluloselike morphology and which are known as, fibrides or synthetic wood pulp. They are used for finishing paper and special boards to impart such features as sealability and improved wet strength. They are also reported to be used for such diverse applications as tile adhesives, thixotropic agents, battery separators and teabags ... 

The effluent from this fixed bed reactor, both vapor and liquid, goes to the catalytic distillation column where the reaction continues, converting almost all the remaining isobutylene as the gaseous C4 s, and methanol rises through the catalyst. The catalyst in this vessel is loaded in bales, sometimes called Texas teabags. As the reaction proceeds, MTBE, a lower boiling point liquid than the C4S and methanol, drops out of die bottom of the column as a liquid. The... 

The resin-bound amino acids (480 teabags) were treated with 15 equiv. of trityl chloride (0.1 M in 90% DMF/10% DCM) containing 20 equiv. of DIEA for 3 h. Following washes with DMF, the resin-filled teabags were dried overnight under high vacuum. 

All manipulations were carried out under nitrogen atmosphere in a glovebox. Lithium t-butoxide (0.5 M, 20 equiv.) in THF was added to the 480 teabags. After shaking for 15 min, the base solution was removed. Sixty equivalents of benzyl bromide in DMSO was added and the teabags were shaken for 2 h. The alkylation solution was removed. Deprotonation and alkylation were repeated three times. Following washes with DMF, IP A, and DCM, the resin packets were dried under high vacuum. 

The trityl-protecting group was removed by treatment of the 480 teabags with 2% TFA in DCM (twice for 10 min). 

Standard SPPS methodology was used (6 equiv. of Fmoc amino acid or Fmoc amino acid mixture, 6 equiv. DIC/HOBt, 1 h in DMF). Twenty-seven Fmoc amino acids were coupled individually to 135 resin-filled teabags (numbered 4730 56, 4830 56, 4930 56, 5030 56, 513 56). A mixture, containing 27 Fmoc amino acids in a predetermined isokinetic ratio,46 was coupled to 345 resin-filled teabags (numbered 47] 29- 4757 96, 48i 29,... 

Standard SPPS methodology was used (10 equiv. of carboxylic acid or carboxylic acid mixture, 10 equiv. DIC/HOBt, 12 h in DMF). Forty carboxylic acids were coupled individually to 200 resin-filled teabags (numbered 4757 96, 4857 96, 4957 96. 5057 96, 5157 A mixture, containing 40 carboxylic acids in a predetermined isokinetic ratio,23 was coupled to 280 resin-filled teabags (numbered 47] 56. 48 ] 56. 49 ] 56. 50] 56. 51] 56). The resin-filled teabags were dried overnight under high vacuum. 

All the teabags were put into a resin kettle under nitrogen. Fifteen equivalents of boric acid and 15 equiv. of trimethylborate were added followed by the slow addition of 45 equiv. of borane (1 M in THF). After hydrogen production ceased, the reaction was heated at 65° for 72 h. The reaction solution was decanted and quenched by the slow addition of methanol. The resin was washed with methanol, THF, and piperidine. The polyamine-borane complex was disproportionated by overnight treatment (16 h) with piperidine at 65° followed by washes with DMF, DCM, and methanol. 

To obtain the non-support-bound libraries 47 to 51, the heterocyclic compounds, still contained within their teabags, were cleaved for 7 h with hydrogen fluoride/anisole using a multivessel apparatus47 for simultaneous cleavage. 

Employing the teabag approach for parallel synthesis, the reagent mixture method, and the libraries from libraries concept, a wide range of different small molecule compounds was successfully prepared in our laboratory during the past decade. Starting from amino acids and short... 

This technique is still evolving. The favored approach at present is to submerge a small, known amount of suspension inside a secured Durapore (polyvinylidene fluoride) membrane pouch (Millipore Products, Bedford, MA) of suitable porosity in teabag fashion in a suitable dissolution medium using the USP Method 1 Paddle Apparatus. Optimization of experimental conditions (rate of agitation, volume and type of medium, temperature, etc.) must be established to achieve reproducible results. 

Bring Vz gallon of water to aboil and add teabags. Boil for 2 minutes and allow to steep for 20 minutes. Bring another Vz gallon of water to boil in another kettle. Add malt extract and boil for 20 minutes. Combine wort and tea... 

An elegant method for the solid-phase synthesis of quinolinone 9 derivatives has been developed by Pei et al. [43]. Using the teabag technology, the synthesis of a 4-amino-3,4-dihydro-2(l//)-quinolinone library was carried out through the rearrangement of /3-lactam intermediates on the solid phase. The condensation of o-nitrobenzaldehyde with a resin-bound amino acid yielded an imine that, following [2-1-2] cycloaddition with ketenes, afforded the -lactams (Fig. 3g). 

The supports used for these methods include standard resins, polymers packaged in permeable teabag -style containers [8], derivatized plastic pins [9], and membranes [10] (see Chapter 1). The solid supports are typically combined for the common deblocking and washing steps and then separated to perform couplings on individual portions of the support. 

Figure 10.27. The teabag approach to combinatorial peptide synthesis.

Teabag method, an approach in combinatorial peptide synthesis that uses parallel... 

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