Wittig reaction Flashcards
(8 cards)
The melting point of the recrystallized product should be a ________________________
compared to the melting point of the crude product
higher temp and narrower range
Are precipitates mixtures or pure?
Mixtures
Are crystals mixtures or pure?
Pure
T/f: My procedure tells me to add up to 8 mL of boiling ethanol to recrystallize my solid. I can add the whole amount at one time without affecting my yield.
False
In the Wittig reaction, cinnamaldehyde is deprotonated by
NaOH
You find 2 samples with erased labels that look like cinnamaldehyde. You know one is benzaldehyde and one is cinnamaldehyde. Which of the following NMR signals would show you your sample is cinnamaldehyde?
there is a doublet of doublets at 6.7 ppm
there is a doublet at 9.7 ppm
In one of your NMR spectra, the doublet at 9.7 ppm has a J value of 7.5 Hz. Similarly, the doublet of doublets at 6.7 ppm has two J values: 15.7 Hz and 7.5 Hz (one for each “split”). What does that information tell you about the two hydrogens that correspond to those peaks?
the two hydrogens are neighbors and are coupling to each other
If you had leftover cinnamaldehyde in your product, an acid-base extraction can be used to deprotonate the unwanted starting material and purify your product.
False
