Low-molecular-weight byproducts

Apply the reaction mixture to the G-25 column (see Section 2., item 10b) and elute with PBSE at a flow rate of 30 mL/h to remove low molecular weight byproducts of the reaction. Collect the protein peak that elutes at the void vol of the column (total vol, about 7 mL)... 

To precipitate the peptide and extract the low molecular weight byproducts, add 20 mL ethylacetate and stir after 5 min, filter the precipitate through a Buchner funnel, and wash precipitate with more ethylacetate. 

The Sol-Gel Reaction. The general sol-gel reaction scheme is composed of a series of hydrolysis steps in conjunction with condensation steps (Scheme I). Both the hydrolysis and condensation steps generate low-molecular-weight byproducts. These byproducts often cause serious complications in the preparation of thick crack-free solid materials because of the drying stresses incurred by their removal. 

The cracking of alkanes initially produces unsaturated, low molecular weight byproducts which can polymerise and, through coke formation, cause a rapid loss of catalyst activity. This problem can be minimised by using a zeolite with low cokeforming tendencies, e.g. ZSM-S, or by incorporation of a hydrogenation function. 

Ion beam etching, to preferentially degrade one of the polymers. The low molecular weight byproducts evaporate under high vacuum. 

Recently, GooRen et ol. further extended the scope of this process to unreactive enol esters 54, which undergo arylation reactions only yielding the low-molecular-weight byproducts carbon monoxide and acetone (54 56 Scheme 7.12) [30]. An additional advantage is that enol esters 54 are accessed by waste-free addition of... 

Generally, a polycondensation is a stepwise reaction in which any two molecules with complementary functional groups can react while forming a low-molecular-weight byproduct (Fig. 3.2). 

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