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Ugi NMR Analysis
To measure the solubility of several compounds in different solvents.. For a justification of this project see
500ul of solvent is added to 50 one dram vials labeled 1-50. The same compound is added to vials 1,11,21,31,41. A different compound is the added to vials 2,12,22,32,42. This process continues until 50 vials are saturated. This is achieved by vortexing the vial repeatedly. Once the solution gets saturated, the one vials are centrifuged and 300uL of the solution is transferred to a half dram preweighed vial. This vial is set in a speed-vac for overnight evaporation. The dry solid in the vials is weighed the next day to obtained the solubility of the compound in different solvents. The following spreadsheet gives the compunds used and the solvents used to dissovle the compounds.
Pictures are linked to a Flickr page here,
The calculated concentration and density of saturated solutions are in the
The values for 4-chlorobenzaldehyde are very low in all solvents, including chloroform.--
This is due to the prolonged time left in the speed-vac and the volatility of this aldehyde. Boiling point of 4-chlorobenzaldehyde at 1 atm. is 213-215 C (
) and the boiling point at 0.1 Torr is calculated to be 19 C(using a
reduced press. b.p calculator
). Since the pressure of the Speed-Vac can reach 0.05-0.1 Torr and the evaporation lasted 6 hours the solubility measurements for 4-chlorobenzaldehye are not valid. The b.p of 2,6-dichlorobenzaldehyde at 1atm is 239.2 °C (
), however saturated solutions of this compound in different solvents showed a concentration range between 0.42 M-3.41 M. This may indicate that only a very small amount of dry 2,6-dichlorobenzaldehyde may have evaporated, if at all. A similar trend is also seen with respect to 4-hydroxy benzaldehyde. Therefore the solubility values obtained for these compunds (but not 4-chlorobenzaldehyde) may still be used.
The densities for each solvent were determined by charging a small vial with 300ul of the solvent and measuring the differences in weight.
Methanol, chloroform, and THF did contain some error (
) from the literature value. The experimental values are in the
The solubilities of ten aldehydes were obtained in different solvents. Compounds with boiling points under 250C at 1 atm may not give valid solubility measurements when using the SpeedVac technique for several hours at about 0.1 Torr. Certainly for 4-chlorobenzaldehyde (b.p. 214C @ 1 atm) the measurement is unusable.
11:00 Preweighed 50 half dram vials and labeled them 1b-50b.
12:00 Labeled 50 one dram vials in numerical order 1a-50a.
12:15 Charged each vial with number specific solvent (listed in the spreadsheet)
12:30 Charged each vial with specific aldehyde, vortexed each for 30s. If solution was clear more sample was added until solution was saturated.
13:15 Skipped over samples 12, 22, 32, 42 since not enough reagent was available.
13:35 4th row was skipped, not enough reagent.
15:25 Samples were finished with saturation step.
12:30 Solvent twas added to appropriate vials from which solvent had evaporated- All the vials had been capped tight (flip top) (
- next time get pic at this stage
13:20 Samples were vortexed again, until no more of the solid would dissolved..the vortex time varied from few seconds to about 7min, exact duration of vortex not recorded.
13:55 Samples were centrifuged.
13:57 Sample cracked in centrifuge; these solutions were remade in different vials and centrifuged carefully..
14:30 Then 300uL of the supernatant from each vial was carefully transferred to a corresponding half dram vial.
15:00 The vials with clear solutions (300uL each) were weighed.
16:00 The vials were capped after they were weighed.
09:30 Placed the half dram in the speed-vac.
15:30 Removed the vials from the speed-vac.
16:00 Weighed the vials.
11:00 Obtained pictures of the vials (one dram vials a-series, and the half dram vials b-series, which were left capped).
16:00 Obtained densities of solvents by charging small vials with 300ul of each solvent. Here in the
12:20 Weighed an empty half dram vial (with a screw cap), labelled
12:25 Added 300uL Chloroform-d (CDCl3) to the vial and immediately capped it tight, this is
-3.97493g - weight of 300uL CDCl3 - 555.93mg; therefore density of CDCl3 is 1.48g/mL
18:25 Obtained a HNMR of 4-Chlorobenzaldehyde in CDCl3.
10:20 Calculated the boiling point of 4-chlorobenzaldehyde using the web based
reduced pressure bp calculator
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