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US 4,057,562 AGranted
Certain naphthofurans and method for their manufacture
AssigneeCiba-Geigy Corporation
InventorsHeinz Balli, Albert Egger
Life of this patent
Estimating the term…
Abstract
The invention relates to specific naphthofurans which are useful as cryochromic substances e.g. for measuring the temperature, pH value or radiation field.
Claims6
A furan of the formula ##STR9## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently alkyl of 1 to 4 carbon atoms or phenyl;
- and the phenyl rings A and B are independently unsubstituted or are substituted by alkyl of 1 to 4 carbon atoms or halo.
A process for the preparation of a furan of the formula ##STR11## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently alkyl of 1 to 4 carbon atoms or phenyl;
- and the phenyl rings A and B are independently unsubstituted or are substituted by alkyl of 1 to 4 carbon atoms or halo;
- which comprises reacting
- a. the naphtholactone of the formula ##STR12## with b. at least one aniline of the formula ##STR13## wherein Y and Y' are each hydrogen, at 150.degree. to 220.degree. C.
Dependencies are inferred from the claim text.