May I please ask the right procedure for reduction of sodium borohydride? I need to reduce ployethyleinimine and need a procedure using the said reagent. Thank you.
http://commonorganicchemistry.com/Rxn_Pages/Reductive_Amination/Reductive%20Amination_NaBH4.htm
the word "ployethyleinimine" is wrong. do you mean polyethyleneimine? this molecule is made by polymerizatio of aziridine and it is saturated: -(CH2-CH2-NH-)n. If you mean -(CH=CH-NH)n, then you can dissolve it in methanol, heat to reflux and add dropwise a commercial aqueous solution of 20% NaBH4 in 20% NaOH. Alternatively dissolve NaBH4 in methanol containing pre-dissolved one pellete of NaOH. NaOH stabilized NaBH4 solution. See for example: Article Reduction of Schiff Bases with Sodium Borohydride
J. Org. Chem. 1957, 22, 9, 1068-1070"Reduction technique A. A 5-10% solution of the Schiff base, dissolved in absolute methanol, was placed in a 3- necked flask fitted with a mechanical stirrer, a dropping funnel, and a reflux condenser. A 2-10% solution of sodium borohydride, double the molar amount of Schiff base, was dissolved in absolute methanol. When the dropwise addition of the sodium borohydride was complete, the reaction solution was refluxed an additional 15 min. and then cooled. To t,his solutuion was added an equal volume of cold tap water whereby a precipitate of the secondary arnine formed. In some earlier experiments, the secondary amine was liberated by the addition of a molar amount of sodium hydroxide which was twice that of the sodium borohydride used. In these cases, the sodium hydroxide was added as a 6N solution; this being followed by the addition of cold tap water which was equal in volume to that of the total solution. The precipitate of secondary amine was then collected by suction filtration, washed with water, and dried. In many cases the product was of sufficient purity that no recrystallization was necessary".
Dear Riana Gabrielle,
Dissolve your's substrate in MeOH(10 vol) and add NaBH4 (mmol's depending the number of reducable functional groups) at a slow rate for few minutes under 0 oC followed by continuing the reaction at 25 oC. Hope this may give you the result in 3-5 hrs. As mentioned yours substrate is polymer, better to add excess equivalents of NaBH4 to complete the reaction. Do not get confused. Sometimes you may get product in the same RF over TLC.
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