| 摘要 |
<p>The invention comprises the leuco compounds of formula <FORM:0822846/IV(c)/1> where R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl or isopentyl, R2 is methyl or ethyl, and R3 = R4 and is methyl, ethyl, n-propyl or isopropyl. The compounds may be prepared by reacting a thiophenaldehyde of formula <FORM:0822846/IV(c)/2> with a di-N-substituted aniline. The compounds are used as indicators in the Schoenemann reaction, being oxidized to give blue-green compounds.ALSO:The invention comprises compounds of the formula <FORM:0822846/IV (a)/1> where R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl or isopentyl, R2 is methyl or ethyl, and R3 = R4 and is methyl, ethyl, n-propyl or isopropyl. The compounds may be prepared by reacting a thiophenaldehyde of formula <FORM:0822846/IV (a)/2> with a di-N-substituted aniline. The intermediate thiophenaldehydes where R1 is methyl are prepared in examples by reacting pyrotartaric acid monosodium salt with a phosphorus sulphide to form 3-methyl-thiophene, which is then converted to 1-formyl- or 1-acetyl-3-methyl-thiophene, the carbonyl groups are reduced to give R2 = methyl or ethyl, and an aldehyde group introduced in the 5-position. The compounds of the invention are used as indicators in the Schoenemann reaction.</p> |
