Polycarbonates, uses thereof, processes for preparing and purifying same

A lubricating oil useful for refrigerator comprising;

• a polycarbonate represented by the following general formula (II):
• (R.sub.1 O)CH.sub.2 (CH(OR.sub.1)).sub.m CH.sub.2 (OR.sub.1) . . . (II)
• wherein R.sub.1 is a group represented by the following formula (E) or (F) and m is an integer of 1 to 6;
• --(C.sub.3 H.sub.4 O).sub.n COOR.sub.2 . . . (E)
• wherein R.sub.2 is each independently a hydrocarbon group having not more than 30 carbon atoms or a hydrocarbon group containing an ether bond and having 2 to 30 carbon atoms, and n is an integer of 1 to 12,
• --(C.sub.3 H.sub.6 O).sub.n (C.sub.2 H.sub.4 O).sub.p COOR.sub.2 . . . (F)
• wherein R.sub.2 is as defined in the above-mentioned formula (E), and n and p are each an integer of 1 to 12;
• and
• a monocarbonate represented by the following formula (XXX):
• R.sub.i OCOOR.sub.ii . . . (XXX)
• wherein each of R.sub.i and R.sub.ii is independently a hydrocarbon group having 1-36 carbon atoms, or a glycol ether group represented by the following general formula (XXXI):
• R.sub.iii (OR.sub.iv).sub.1 -- . . . (XXXI)
• wherein R.sub.iii is a hydrocarbon group having 1-6 carbon atoms, R.sub.iv is ethylene group or propylene group and l is an integer of 1-100;
• and
• an ozone layer nondestructive refrigerant.