apparatus and processes are disclosed for converting sensitive organic compounds such as acrolein , methacrolein , acrylic acid and methacrylic acid from liquid to vapor in admixture with a gas stream at super - atmospheric pressures with minimum decomposition and substantially without polymer formation . the acrolein and methacrolein partial pressures being up to super - atmospheric and those of acrylic and methacrylic acids up to about an atmosphere . an apparatus and a process are also disclosed for transferring a sensitive organic material in an energy - efficient manner from a low - pressure , high - temperature gas - vapor stream to a solvent for the sensitive material , and then to another gas stream at increased pressure .