1. A process for the preparation of sucralose comprising the steps of:
(i) electrolyzing an anode electrolyte solution comprising sucrose, an acylating reagent and a halide catalyst to produce a sucrose-6-ester;
(ii) chlorinating the sucrose-6-ester to form a 4,1\u2032,6\u2032-trichlorinated sucrose-6-ester; and
(iii) hydrolyzing the 4,1\u2032,6\u2032-trichlorinated sucrose-6-ester to provide sucralose.
2. The process of claim 1, wherein step (ii) is carried out using a chlorinating reagent selected from the group consisting of sulphuryl chloride, thionyl chloride, phosphorus trichloride, phosphorus oxychloride, phosphorus pentachloride, oxalyl chloride, methane sulfonyl chloride and carbonyl chloride.
3. The process of claim 1, wherein step (ii) is carried out in the presence of a chlorination catalyst selected from the group consisting of N,N-dimethylformamide, N,N-diethylformamide and pyridine.
4. The process of claim 1, wherein step (ii) is carried out in the presence of a polar organic solvent selected from the group consisting of butyl acetate, hexyl acetate, cyclohexanone and 1,1,2,2-tetrachloroethane.
5. The process of claim 1, wherein step (iii) is carried out at pH 9-11 using a strong base anion exchange resin column.
6. The process of claim 1, wherein the acylating reagent is an aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propaldehyde, and benzaldehyde.
7. The process of claim 1, wherein the molar ratio of the acylating reagent to sucrose is about 1.0 to 2.5.
8. The process of claim 1, wherein the halide catalyst is a chloride, bromide or iodide.
9. The process of claim 1, wherein the amount of the halide catalyst is about 1%-5% by weight of the electrolyte solution.
10. The process of claim 1, wherein the electrolyte solution further comprises a solvent selected from the group consisting of N,N-dimethylformaide, N,N-diethylformide, N,N-dimethylacetamide, ketones, acetonitrile and aromatic solvents.
11. The process of claim 1, wherein the electrolyte solution further comprises 0.1%-10% by weight of water.
12. The process of claim 1, wherein the electrolyte solution further comprises a supporting electrolyte selected from the group consisting of fluoboric acid quaternary ammonium salts, fluoboric acid lithium salts, perchloric acid quaternary ammonium salts, perchloric acid lithium salts, tetraalkyl-ammonium, tetrachloro-borate and sulfonate.
13. The process of claim 12, wherein the amount of the supporting electrolyte is about 0.1%-15% by weight of the electrolyte solution.
14. The process of claim 1, wherein the temperature is maintained at \u22125\u02dc50\xb0 C. during the electrolysis of step (i).
15. The process of claim 1, wherein step (i) is carried out under an anode potential of about 0.3-0.8V above the standard electrode potential of the redox couple X\u2212XO\u2212, wherein X\u2212 represents the halide ion from the halide catalyst.
16. The process of claim 1, wherein step (i) is carried out in an electrolysis system comprising the anode electrolyte solution containing the sucrose, the acylating reagent and the halide catalyst, and a cathode electrolyte solution, wherein the anode electrolyte solution is separated from the cathode electrolyte solution by a non-selective film having excellent ion permeability.
17. The process of claim 16, wherein the non-selective film is a microporous ceramic film or a glass film.
18. The process of claim 16, wherein the cathode electrolyte solution is an aqueous solution of sodium chloride.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A piezoelectric microactuator configured for third stage actuation in a hard disk drive, said microactuator comprising:
a single sheet of piezoelectric material having a top surface, an opposing bottom surface, a first lateral portion and a second lateral portion, wherein the first lateral portion is poled in a first direction and the second lateral portion is poled in an opposing second direction; and
a single first actuation electrode layer electrically coupled with the top surface and a single second actuation electrode layer electrically coupled with the bottom surface.
2. The piezoelectric microactuator of claim 1,
wherein a drive voltage applied to the first electrode layer in the same direction in which the first lateral portion is poled causes the first lateral portion to contract and the second lateral portion to expand; and
wherein a drive voltage applied to the first electrode layer in the opposite direction in which the first lateral portion is poled causes the first lateral portion to expand and the second lateral portion to contract.
3. The piezoelectric microactuator of claim 2,
wherein the first lateral portion and second lateral portion are configured to expand and contract in a longitudinal direction.
4. The piezoelectric microactuator of claim 1,
wherein the first direction and the second direction are substantially normal to the top surface and to the bottom surface.
5. The piezoelectric microactuator of claim 1, further comprising:
first affixing means coupling said microactuator to a head slider and second affixing means mounting said microactuator to a suspension for rotating said head slider relative to said suspension.
6. A hard disk drive, comprising:
a head slider comprising a magnetic write head;
a magnetic-recording disk rotatably mounted on a spindle;
a voice coil motor configured to coarsely move the head slider to access portions of the magnetic-recording disk;
a microactuator mounted on a suspension and attached directly to said head slider to finely move the head slider to access portions of the magnetic-recording disk;
wherein the microactuator comprises:
a single sheet of piezoelectric material having a top surface, an opposing bottom surface, a first lateral portion and a second lateral portion, wherein the first lateral portion is poled in a first direction and the second lateral portion is poled in an opposing second direction, and
a single first actuation electrode layer electrically coupled with the top surface and a single second actuation electrode layer electrically coupled with the bottom surface; and
a microactuator drive circuit configured to apply drive voltage to the first actuation electrode layer and the second actuation electrode layer to drive the microactuator.
7. The hard disk drive of claim 6,
wherein the drive voltage applied to the first and second actuation electrode layers in the same direction in which the first lateral portion is poled causes the first lateral portion to contract and the second lateral portion to expand; and
wherein a drive voltage applied to the first and second actuation electrode layers in the opposite direction in which the first lateral portion is poled causes the first lateral portion to expand and the second lateral portion to contract.
8. The hard disk drive of claim 7,
wherein the first lateral portion and second lateral portion are configured to expand and contract in a longitudinal direction of the suspension.
9. The hard disk drive of claim 6,
wherein the first direction and the second direction are substantially normal to the top surface and to the bottom surface.
10. A method for manufacturing a piezoelectric microactuator for a hard disk drive, the method comprising:
coating a first surface of a single sheet of piezoelectric material with a first electrode;
coating a second surface of the sheet of piezoelectric material with a conductive poling material;
patterning the conductive poling material to form a first poling electrode on a first portion of the second surface of the sheet of piezoelectric material and a second poling electrode on a second portion of the second surface of the sheet of piezoelectric material;
applying an electrical field to the first poling electrode to pole the first portion in a first direction normal to the sheet of piezoelectric material;
applying an electrical field to the second poling electrode to pole the second portion in a second direction normal to the sheet of piezoelectric material and opposing the first direction; and
depositing a second electrode over the second surface of the sheet of piezoelectric material.
11. The method of claim 10, wherein the coating, patterning, applying and depositing are performed on the sheet of piezoelectric material to fabricate a plurality of piezoelectric microactuators simultaneously, and wherein the method further comprises:
dicing the sheet of piezoelectric material to form the plurality of piezoelectric microactuators.