1-9. (canceled)
10. A process for preparing optically active alkylsuccinic acid monoalkyl esters of the formula (I)
where D and E are independently of one another H, C1-C10 alkyl,
R is C1-C10 alkyl, aryl or alkylaryl,
which comprises enantioselective hydrogenating a compound of the formula (II)
where D,E and R have the abovementioned meanings,
in the presence of a catalyst which includes a phospholane ligand of the formula (L)
where:
R1 and R2 are independently of one another C1-C6 alkyl, aryl, alkylaryl,
R1 is additionally hydrogen,
A is either R1 or
with B a linker with 1-5 C atoms between the two P atoms or Cp-Fe-Cp.
11. The process according to claim 10, wherein D and E are hydrogen and R is Me.
12. The process according to claim 10, wherein a ligand from the group of Rophos A, Rophos B, Me-KetalPhos, Me-f-KetalPhos is used as ligand (L).
13. The process according to claim 10, wherein the hydrogenation is carried out under a pressure of between 1 and 100 bar of hydrogen.
14. The process according to claim 10, wherein the hydrogenation is carried out in methanol.
15. The process according to claim 10, wherein the hydrogenation is carried out at a temperature between 10\xb0 C and 80\xb0 C.
16. The process according to claim 10, wherein the catalyst used is immobilized.
17. The process according to claim 10, wherein the reaction product (I) resulting from the hydrogenation is converted into a carboxylate and is removed in this form from the reaction mixture.
18. The process according to claim 17, wherein the reaction product (I) is precipitated in the form of an Li carboxylate from the reaction mixture.
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. An optical glass that is an oxide glass and comprises, by cationic %,
20 to 40% of a total of Si4+ and B3+,
15 to 40% of a total of Nb5+, Ti4+, W6+ and Zr4+,
0.2 to 20% of a total of Zn2+, Ba2+, Sr2+ and Ca2+, and
15 to 55% of a total of Li+, Na+ and K+,
the cationic ratio of the content of B3+ to the total content of B3+ and Si4+ being 0.01-0.5,
the cationic ratio of the content of Zr4+ to the total content of Nb5+, Ti4+, W6+ and Zr4+ being 0.05 or less,
the cationic ratio of the content of Nb5+ to the total content of Nb5+ and T4+, (Nb5+(Nb5++Ti4+)), is 0.65-1,
the molar ratio of the total content of Zn2+ and Ba2+ to the total content of Zn2+, Ba2+, Sr2+ and Ca2+ being 0.8-1,
the optical glass having a refractive index nd of 1.815 or more and an Abbe’s number vd of 29 or less.
2. The optical glass of claim 1, which has a glass transition temperature of less than 530\xb0 C.
3. The optical glass of claim 1, which has a liquidus temperature of 1,080\xb0 C. or lower.
4. The optical glass of claim 1, which has an Si4+ content of 15 to 30%.
5. The optical glass of claim 1, which has a B3+ content of 15% or less.
6. The optical glass of claim 1, which has an Nb5+ content of 10 to 30%.
7. The optical glass of claim 1, which has a Ti4+ content of 0 to 15%.
8. The optical glass of claim 1, which has a W6+ content of 0 to 4%.
9. The optical glass of claim 1, which has a Zr4+ content of 0 to 4%.
10. The optical glass of claim 1, which has a Zn2+ content of 9% or less.
11. The optical glass of claim 1, which has a Ba2+ content of 6% or less.
12. The optical glass of claim 1, which has an Sr2+ content of 2% or less.
13. The optical glass of claim 1, which has a Ca2+ content of 3% or less.
14. The optical glass of claim 1, which has an Li+ content of 25% or less.
15. The optical glass of claim 1, which has an Na+ content of 30% or less.
16. The optical glass of claim 1, which has a K+ content of 25% or less.
17. The optical glass of claim 1, wherein the cationic ratio of the content of Li+ to the total content of Li+, Na+ and K+ is 0.1-1.
18. The optical glass of claim 1, which has a \u0394Pg,F of 0.0130 or less.
19. An optical element formed of the optical glass recited in claim 1.
20. An image-sensing device having the optical element recited in claim 19.
21. A precision press-molding preform formed of the optical glass recited in claim 1.
22. A process for producing a precision press-molding preform, which comprises manufacturing the preform recited in claim 21 through the steps of heating and melting glass raw materials to prepare a molten glass and shaping said molten glass.
23. A process for producing an optical element, which comprises the steps of heating the precision press-molding preform recited in claim 21 and precision press-molding the preform with a press mold.
24. The process for producing an optical element as recited in claim 23, wherein the precision press-molding preform and the press mold are heated together and the preform is precision press-molded.
25. The process for producing an optical element as recited in claim 23, wherein the precision press-molding preform is heated and then introduced into the press mold that is pre-heated, and the preform is precision press-molded.