The risk of ignition during the addition of NaH to the reactor was eliminated by using NaH in dissolvable bag packaging (SecuBags) from Chemetall Foote Corp. The risks associated with waste disposal of unused NaH were also eliminated since the bags were purchased in premeasured quantities; the entire bag was used in the reaction.The authors describe a chloropyrimidine displacement using an unnamed alcohol with the bagged sodium hydride (60% in an oil dispersion) and MeTHF at reflux; they used a mass spectrometer in line with the reactor to monitor hydrogen off-gassing. The authors also cover the quenching of the sodium hydride with 4% wet MeTHF, analysis of the product and analysis for remnants of the bag in the product:
The SecuBag is made of styrene-butadiene-styrene (SBS) block copolymers. To ensure the SecuBag was sufficiently removed during the filtration, analytical methods were developed to rest for residual SecuBag and styrene in the isolated product. An analytical method that was developed to monitor residual SecuBads polymer used size exclusion chromatography with UV detection at 215 nm... The batch samples contained SecuBags polymer in the range of 120-250 ppm with respect to total weight of the sample analyzed, which was well below the ICH recommended level of 1000 ppm.
...[regards to potential styrene in the product] Analysis of a concentration of 0.1 g/mL for pyrimidine 3 with a detection limit of 5 ppm styrene demonstrated that styrene was not detectable in any of the four batches produced by the described process.I suppose I'm a little bit surprised that there's still a little bit of the polymer from the bag in the product, but apparently there's not much harm and it's still well within regulatory specifications. [Presumably, downstream processing would take care of it?]
Sounds neat -- now I want to try it.
 McCabe Dunn, J.M.; Duran-Capece, A.; Meehan, B.; Ulis, J.; Iwama, T.; Gloor, G.; Wong, G.; Bekos, E. Org. Process. Res. Dev. ASAP. DOI: 10.1021/op200114t