I'm conducting a synthesis involving crown ether and Pd catalyst. In many papers, prior to column chromatography, they filter crude mixture through a Celite pad. I tried to, but leakage of Celite occurred. Referring to this paper : https://pubs.acs.org/doi/10.1021/jo005577d (see General Procedure part), I started the reaction with 10 mL of toluene as solvent, and continued work-up with 60 mL dichloromethane. In some cases the filtrate seemed to contain Celite, and the other cases, once I turn on the vacuum pump, some of Celite powder fell down to the collecting flask. What did I mistake? I used Buchner filter, and almost-fitted filter paper (55mm diameter, 1 μm pore size). Basically I referred to this video : https://youtu.be/oAzScPuZqjU. (In this video, after first filtration to make pad, he washes collecting flask and continues second filtration. Both images I uploaded are about second filtration.)

basic filtration setup filtrate seems to contain Celite

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    $\begingroup$ The problem is the "almost fitted" filter paper. Do you have access to sintered glass filters? $\endgroup$
    – Waylander
    Jul 15 '21 at 8:33
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    $\begingroup$ According to Vogel's practical organic chemistry, it says that a filter paper should cover the entire perforate plate, but its diameter should be slightly less than the inside diameter of funnel. so I thought, 'Is the filter paper "too fitted?"', so I tried to cut some of its circumference and filtrated again, but it didn't work. (even before I turn on the vacuum pump, Celite slurry almost fell down.) I have sintered glass filter, but I don't have appropriate-sized filter paper. $\endgroup$
    – Krang Lee
    Jul 15 '21 at 8:39
  • $\begingroup$ sorry for misleading word, 'almost-fitted' should be corrected to 'almost completely-fitted'. $\endgroup$
    – Krang Lee
    Jul 15 '21 at 8:41
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    $\begingroup$ @KrangLee If you are sure that paper fitting isn't an issue, then probably celite particles size is. Are you using Celite 545? Alternatively, make sure you are not rapidly applying vacuum — this might cause some particles to puncture the filter paper. $\endgroup$
    – andselisk
    Jul 15 '21 at 8:59
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    $\begingroup$ If you have a sintered glass filter you do not need a filter paper. Make up the celite/solvent slurry in the filter then apply the suction to form the Celite pad. $\endgroup$
    – Waylander
    Jul 15 '21 at 11:14

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