Abstract: A process for preparing pyridine-2,3-dicarboxylic acid compounds of the following formula, which comprises preparing .alpha.-halo-oxalacetic acid diesters by reacting oxalacetic acid diester alkali metallic salts with an acid and a halogenating agent or by reacting oxalic acid diesters with halo-acetic acid esters, and then reacting the obtained .alpha.-halo-oxalacetic acid diesters with 2-propenal compounds and ammonia. ##STR1## wherein R.sup.1 and R.sup.2 are, identical or different, a lower alkyl group, and R.sup.3 is a hydrogen atom or a lower alkyl group.The pyridine-2,3-dicarboxylic acid compounds obtained by the process of the invention are useful as an intermediate for manufacturing agricultural chemicals and pharmaceuticals.

Abstract: A process for preparing pyridine-2,3-dicarboxylic acid compounds of the following formula, which comprises preparing .alpha.-halo-oxalacetic acid diesters by reacting oxalacetic acid diester alkali metallic salts with an acid and a halogenating agent or by reacting oxalic acid diesters with halo-acetic acid esters, and then reacting the obtained .alpha.-halo-oxalacetic acid diesters with 2-propenal compounds and ammonia. ##STR1## wherein R.sup.1 and R.sup.2 are, identical or different, a lower alkyl group, and R.sup.3 is a hydrogen atom or a lower alkyl group.The pyridine-2,3-dicarboxylic acid componds obtained by the process of the ivention are useful as an intermediate for manufacturing agricultural chemicals and pharmaceuticals.

Abstract: A process for preparing pyridine-2,3-dicarboxylic acid compounds of the following formula: ##STR1## wherein R.sup.1 and R.sup.3 are, identical or different, each a hydrogen atom or a lower alkyl group, R.sup.2 is a hydrogen atom, a lower alkyl group, or a phenyl-(lower)alkyl group which may have halogen atom or lower alkyl group on its phenyl ring, and R.sup.4 and R.sup.5 are, identical or different, each a lower alkoxy group.The compounds are useful as an intermediate for preparing agricultural chemicals and pharmaceuticals.

Abstract: Disclosed is a heat sensitive sheet which can develop a black image having excellent oil and light resistance, comprising a combination of a record sheet to be printed and a transfer sheet for forming an image on said record sheet, wherein said record sheet is coated with a solution comprising an organic or inorganic nickel compound an an organic and inorganic copper compound and said transfer sheet is coated with dithiooxamide. The present invention also provides a transfer sheet which can form a printed black image having excellent oil and light resistance on any type of record sheets. The transfer sheet is coated with an organic compound having a phenolic hydroxyl group or an amino group directly bonded to aromatic ring and quinone or a quinone derivative substituted by an electron attractive group in such a condition that the organic compound is not reacted with quinone or the quinone derivative.