Aromatic cyanic acid esters
AssigneeBayer Aktiengesellschaft
InventorRudolf Sundermann
Life of this patent
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Abstract
Aromatic cyanic acid esters having a free hydroxyl group which is not sterically hindered are prepared by reacting aromatic dihydroxy and polyhydroxy compounds with cyanogen halide in aqueous solution in the presence of a water-immiscible organic solvent and an inorganic base. Aromatic cyanic acid esters prepared by the process have the formula ##STR1## wherein Ar is optionally substituted aromatic and n and m are the same or different and are one of the numbers from 1 to 5, with the sum m and n being not greater than the number of replaceable hydrogen atoms in the radical Ar.
Claims3
Aromatic cyanic acid esters of the formula ##STR13## wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are the same or different and are hydrogen, halogen or alkyl,
- A is a bond between the aromatic rings or divalent alkyl with up to 6 carbon atoms, optionally substituted by lower alkyl, optionally substituted 5-membered or 6-membered cycloaliphatic, sulphonyl (--SO.sub.2 --) or carbonyl (--CO--),
- wherein
- s and t are the same or different and are one of the numbers from 1 to 5.
Cyanic acid esters of the formula ##STR14## wherein Ar is optionally substituted aromatic and n and m are the same or different and are one of the numbers from 1 to 5, with the sum m and n being not greater than the number of replaceable hydrogen atoms in the radical Ar,
- said ester being from the group of
- 4-(4-Hydroxyphenylisopropyl)-phenyl cyanate,
- 2-(3,5-Dimethyl-4-hydroxyphenyl)-2-(3,5-dimethyl-4-cyanatophenyl)-propane,
- 2-(3,5-Dichloro-4-hydroxyphenyl)-2-(3,5-dichloro-4-cyanatophenyl)-propane, and
- 1-(4-Hydroxyphenyl)-1-(4-cyanatophenyl)-cyclohexane.
Aromatic cyanic acid esters of the formula ##STR15## wherein R.sup.1 and R.sup.2 are the same or different and are alkyl or halogen and
- o and p are identical or different and represent one of the numbers from 1 to 5 and
- q and r are identical or different and represent one of the numbers 0, 1 or 2
- with the sum of the numbers o, p, q and r being a maximum of 6
- selected from the group consisting of m-hydroxyphenyl cyanate, p-hydroxyphenyl cyanate, 4,6-dimethyl-3-hydroxyphenyl cyanate, 2,3,5,6-tetramethyl-4-hydroxyphenyl cyanate and 5-methyl-3-hydroxyphenyl cyanate.
Dependencies are inferred from the claim text.