| abstract |
A composition is disclosed which comprises a lubricating oil and a refrigerant, wherein the lubricating oil comprises a polyalkyleneglycol derivative of the formula (I): RX(RaO)x(RbO)y(RcO)zRd, wherein: X = O or S, R is a C¿3? to C15 substituent comprising a heterocyclic ring, in which the heteroatom(s) in said ring is (are) oxygen and/or sulphur, R?a¿ is a C¿2? alkylene group, R?b¿ is a C¿3? alkylene group, R?c¿ is a C¿4? alkylene group, R?d¿ is the same as R, or is H, a C¿1?-C20 alkyl or a C1-C20 acyl, x, y, z are each independently 0 or an integer of 100 or less, and x + y + z = 4 to 100, but excluding compositions where the refrigerant is halogen-free and R contains a carbonate group. The use of borate esters as dehydrogenating agents in conjunction with the above lubricating oils is also disclosed. |