Novel low VOC solvent-based adhesives are provided, comprising a mixture of low vapor pressure, isomeric dimethyl-2-piperidones (DMPD) blended with (1) a non-solvent diluent, specifically, acetone (a VOC-exempt compound), or with mixtures of acetone and other known ketonic solvents such as methyl ethyl ketone (MEK), diethyl ketone (DEK), methyl propyl ketone (MPK), and methyl iso-butyl ketone (MIBK), cyclohexanone, and (2) thermoplastic PVC or CPVC resins. Omission of the resin provides a novel primer for pipes. The blended mixture yields PVC or CPVC pipe adhesives and primers that: (1) result in low VOC formulas (e.g., less than 510 g / l for PVC pipe and less than 490 g / l for CPVC pipe); (2) are very economical in the industry; (3) yield strong, quick setting, durable pipe joints that meet the required standards and performance criteria (e.g., ASTM D-2564 lap shear for PVC); (4) yield stable, low viscosity solutions that, in the case of adhesives, can be readily adjusted with thixotropes (e.g., Aerosil 200) to give desirable flow characteristics and body, as well as primers for solvent welding PVC and CPVC pipe and components; and (5) can be formulated with minimal (10 wt %) or no cyclic ethers such as THF.