Preparation of terpyridines

A process for preparing C1-C4-alkyl pyridine-2-carboxylate derivatives of the formula a

• 30
• in which
• R is hydrogen or a C1-C12-alkyl or C1-C12-alkox radical and
• n is 0, 1, 2, 3 or 4,
• by acid hydrolysis of a 2-cyanopyridine derivative of the formula a′
• 31
• by means of an anhydrous inorganic acid or its anhydride in the presence of water and a C1-C4-alkanol, wherein an equimolar amount of water is added to the 2-cyanopyridine derivative of the formula a′ prior to addition of the anhydrous inorganic acid or its anhydride.

A process for preparing 1,5-bis(2-pyridyl)pentane-1,3,5-trione derivatives of the formula b

• 32
• in which
• R are hydrogens or identical C1-C12-alkyl or C1-C12-alkoxy radicals and
• n is 0, 1, 2, 3 or 4 and is the same for both sets of radicals R,
• by condensation of the C1-C4-alkyl pyridine-2-carboxylate derivative of the formula a
• 33
• with acetone in an aprotic solvent in the presence of an alkali metal C1-C4-alkoxide or alkaline earth metal C1-C4-alkoxide as base.

A process for preparing 2,6-bis(2-pyridyl)-4(1H)pyridinone derivatives of the formula c

• 34
• in which
• R are hydrogens or identical C1-C12-alkyl or C1-C12-alkoxy radicals,
• n is 0, 1, 2, 3 or 4 and is the same for both sets of radicals R,
• Z is NH or NH2⊕[Y1/q]⊖ and
• Y is the anion of a q-basic acid HqY,
• by reacting the 1,5-bis(2-pyridyl)pentane-1,3,5-trione derivative of the formula b
• 35
• with ammonia or ammonium salts (NH4)qY with removal of the water of reaction formed, wherein the removal of the water of reaction is carried out using a C1-C4-alkanol as entrainer.

A process for preparing terpyridines of the formula I

• 36
• in which
• R are hydrogens or identical C1-C12-alkyl or C1-C12-alkoxy radicals,
• n is 0, 1, 2, 3 or 4 and is the same for both sets of radicals R,
• Z′ is nitrogen or NH⊕ ([Y1/q]⊖ and
• Y is the acid anion of a q-basic acid HqY,
• by chlorination of the 2,6-bis(2-pyridyl)-4(1H)pyridinone derivative of the formula b (b),
• 37
• where Z is NH or NH2⊕ [Y1/q]⊖,
• wherein the chlorination is carried out using phosphorus oxide chloride (POCl3) or using a mixture comprising phosphorus oxide chloride and at least one organic solvent selected from the group consisting of toluene, o-xylene, m-xylene and p-xylene.