Processes for preparing calix[4]arenes from calix[8]arenes

1. A process for a one-pot synthesis of a high-purity calix[4]arene compound, comprising:

reacting a phenolic compound and an aldehyde in the presence of at least one nitrogen-containing base as a catalyst to form a calix[8]arene compound; and

cleaving the calix[8]arene compound into a high-purity calix[4]arene compound, directly, without carrying out a purification step before the cleaving step.

2. The process of claim 1 , wherein the phenolic compound is phenol, an alkyl phenol, or an arylalkyl phenol.

3. The process of claim 1 , wherein the phenolic compound is a para-tert-butyl phenol, para-tert-amyl phenol, para-tert-octyl phenol, para-benzyl phenol, or para-cumylphenol.

4. The process of claim 1 , wherein the aldehyde is formaldehyde or paraformaldehyde.

5. The process of claim 1 , wherein the process is carried out in the absence of a recrystallization step.

6. The process of claim 1 , wherein the reacting step is carried out in the presence of an organic solvent.

7. The process of claim 6 , wherein the organic solvent is an aromatic hydrocarbon, a straight-chain hydrocarbon having 11 to 20 carbon atoms, an ether, or a mixture containing thereof.

8. The process of claim 6 , wherein the step of cleaving comprises:

heating the calix[8]arene compound to a temperature of at least about 200° C., in the presence of a metal hydroxide catalyst.

9. The process of claim 8 , wherein the step of cleaving comprises:

heating the calix[8]arene compound at a temperature ranging from about 250 to about 260° C., in the presence of an alkali metal hydroxide catalyst, for a period of 30 minutes or longer.

10. The process of claim 8 , further comprises:

lowering the temperature to precipitate the high-purity calix[4]arene compound.

11. A process for a one-pot synthesis of a high-purity calix[4]arene compound, comprising:

reacting a phenolic compound and an aldehyde in the presence of at least one nitrogen-containing base as a catalyst, in an organic solvent, to form a calix[8]arene compound;

cleaving the calix[8]arene compound into a high-purity calix[4]arene compound, directly, without carrying out a purification step before the cleaving step; and

adding an antisolvent to precipitate the calix[4]arene compound having a purity of at least 95%.

12. The process of claim 11 , wherein the antisolvent is an ester, ketone, alcohol, or acetonitrile.

13. The process of claim 1 , wherein the high-purity calix[4]arene compound comprises 4 units of formula (A-1):

wherein:

each of R 1 and R 2 is independently linear, branched, or cyclic C 1 -C 30 alkyl, aryl, alkylaryl, or arylalkyl;

each L is independently selected from the group consisting of —CH 2 —, —C(O)—, —CH(R 3 )—, —(CH 2 ) n′ —O—(CH 2 ) n′ —, —C(R 3 ) 2 —;

each R 3 is independently a C 1 -C 6 alkyl;

each n′ is independently an integer from 1-2; and

each A 1 represents a direct covalent bond to an adjacent unit of formula (A-1) such that there is one L group between adjacent units, whereby the total units in the calixarene compound form a ring.

14. The process of claim 13 , wherein each R 1 is methyl, and each R 2 is methyl, ethyl, propyl, or hexyl.

15. The process of claim 13 , wherein the calix[4]arene compound is at least partially soluble in a hydrocarbon solvent at room temperature.

16. The process of claim 15 , wherein the solubility of the calix[4]arene compound in toluene is at least 5 wt % at about 21° C.

17. The process of claim 13 , wherein the reacting step is carried out in the presence of an organic solvent, and wherein the process further comprises:

adding an antisolvent to precipitate the calix[4]arene compound having a purity of at least 94%.

18. The process of claim 17 , wherein the antisolvent is acetone or isopropanol.

19. The process of claim 17 , further comprising, prior to adding the antisolvent:

neutralizing the metal hydroxide catalyst by adding an acid; and

removing, at least partially, the organic solvent by distillation.

20. A process for improved conversion of a calix[8]arene compound to a calix[4]arene compound, comprising:

providing a calix[8]arene compound; and

cleaving the calix[8]arene compound in a glycol ether solvent having a boiling point of at least about 200° C., to result in a high-purity calix[4]arene compound, without using an antisolvent.

21. The process of claim 20 , wherein the glycol ether solvent has a boiling point ranging from about 250 to about 260° C.

22. The process of claim 21 , wherein the glycol ether solvent is diethylene glycol dibutyl ether.

23. The process of claim 20 , wherein the step of cleaving comprises:

heating the calix[8]arene compound at a temperature of at least about 200° C., in the presence of a metal hydroxide catalyst.

24. The process of claim 23 , wherein the step of cleaving comprises:

heating the calix[8]arene compound at a temperature ranging from about 250 to about 260° C., in the presence of an alkali metal hydroxide catalyst, for a period of about 30 minutes or longer; and

lowering the temperature to precipitate the calix[4]arene compound having a purity of at least 98%.

25. The process of claim 20 , wherein the calix[8]arene compound comprises 8 units of formula (A-1):

wherein:

each of R 1 and R 2 is independently linear, branched, or cyclic C 1 -C 30 alkyl, aryl, alkylaryl, or arylalkyl;

each L is independently selected from the group consisting of —CH 2 —, —C(O)—, —CH(R 3 )—, —(CH 2 ) n′ —O—(CH 2 ) n′ —, —C(R 3 ) 2 —;

each R 3 is independently a C 1 -C 6 alkyl;

each n′ is independently an integer from 1-2; and

each A 1 represents a direct covalent bond to an adjacent unit of formula (A-1) such that there is one L group between adjacent units, whereby the total units in the calixarene compound form a ring.