Handbook of Solvents - George Wypych - ChemTech - Ventech!

15.2.3 An innovative GC method 1117
Figure 15.2.3.2. SEM photograph of paracetamol
recrystallized in dioxane and submitted to moderate
drying (Photograph from reference 2 ).
Figure 15.2.3.4. SEM photograph of paracetamol
recrystallized in dioxane and submitted to drastic drying
(Photograph from reference 2 ).
same polymorphic form: the monoclinic form.
Figure 15.2.3.3. SEM photograph of paracetamol
recrystallized in dioxane and submitted to progressive
drying (Photograph from reference 2 ).
The optical microscopy investigation
shows some significant differences in mean
diameter and crystal habit due to crystallization
conditions.
In the case of water and ethanol, the
crystals are transparent and rather regular,
their habit is generally parallelepipedal. The
only difference to be noted is the mean diameter
of these particles; the particles
recrystallized in water being 3 times larger.
ESM reveals a surface that remains smooth
in all drying conditions; their texture seems
compact and dense.
In contrast, crystals obtained from
dioxane are rather different to those obtained
from ethanol and water: they are opaque to
transmitted light and their habit is irregular.
Their mean diameter is slightly smaller than
crystals from ethanol.
It is to be noted that all the crystals obtained
from the three solvents present the
Table 15.2.3.3: Mean Ferret diameters of particles (Data from references 2,3 )
Monocrystalline Mean diameter, Polycrystalline Mean diameter,
particles
μm
particles
μm
paracetamol / dioxane 122 meprobamate spherical crystals 145
paracetamol / ethanol 149 ibuprofen agglomerates 350
paracetamol / water 538 paracetamol spherolites 113