34
Setting up a Synthesis
WARNING
Handle all chemicals under a fume hood, and wear suitable protective clothing such as safety glasses,
chemical resistant gloves, and a laboratory coat. Dispose of all waste in accordance with all applicable
local, state, and federal health and safety recommendations. For detailed information on the safety
requirements for the chemicals used on the Liberty Blue, refer to the appropriate SDS documents.
Resin Selection
Default cycles are available for both standard resins (such as polystyrene) and high-swelling resins (such as PEG).
It is important to use the appropriate cycles for the resin being used in the synthesis. When the resin type is
selected in the Liberty Method Editor, the appropriate default cycles for that type will automatically be loaded.
Although most resins are compatible with microwave SPPS on the Liberty Blue, CEM recommends the resins
shown in the table below for optimal results.
Peptide Length C-Terminal Acid C-Terminal Amide
Standard (<25 residues) Cl-TCP(Cl) ProTide Fmoc Rink Amide ProTide
Long (>25 residues) Cl-MPA ProTide (LL) Fmoc Rink Amide ProTide (LL)
Mesh Size
Only 100-200 mesh (or lower) resin (>75 micron) should be used with the Liberty Blue. The use of higher mesh
resins will result in clogging of the reaction vessel frit and damage to the system.
Deprotection Solution Selection
General Strategy
Historically, piperidine has been the most common deprotection reagent. Piperazine, however, is a great alternative
and is growing in popularity; it is a non-controlled substance, relatively inexpensive, and less malodorous than
piperidine. Although piperizine has limited solubility in DMF and NMP, it shows improved solubility and deprotection
activity in a solution of 10% ethanol in NMP.
CEM Preference Deprotection Cocktail Microwave Method
1 20% Piperidine (v/v) in DMF or NMP Standard
2 10% (w/v) Piperazine in EtOH:NMP (10:90) Standard
For sequences where aspartimide formation is a concern, 0.1 M HOBt or 0.1 M Oxyma should be added to the
deprotection cocktail to suppress the side reaction.
NOTE
Allow up to 1 hour for piperazine to completely dissolve with stirring. If 0.1 M Oxyma is added then 30
minutes is enough to completely dissolve with stirring. Gentle heating on a hotplate can help. Calibration
of the deprotect timed addition should be performed for the particular reagent used (piperazine or
piperidine).
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