TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The composition comprises: HFC-1234yf (1-99 wt.%); and at least one compound (1-99 wt.%) comprising propane, n-butane, isobutane and/or DME. The composition further comprises: a lubricant comprising polyol esters, polyalkylene glycols, polyvinyl ethers, mineral oil, alkylbenzenes, synthetic paraffins, synthetic napthenes, or poly (alpha)olefins; and a tracer comprising hydrofluorocarbons, deuterated hydrocarbons, deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodated compounds, alcohols, aldehydes, ketones, and/or nitrous oxide. The composition further comprises at least one ultraviolet fluorescent dye comprising naphthalimides, perylenes, coumarins, anthracenes, phenanthracenes, xanthenes, thioxanthenes, naphthoxanthenes, fluoresceins and/or their derivatives; at least one solubilizing agent comprising hydrocarbons, dimethylether, polyoxyalkylene glycol ethers, amides, ketones, nitriles, chlorocarbons, esters, lactones, aryl ethers, fluoroethers or 1,1,1-trifluoroalkanes; an odor masking agent; and a stabilizer. The composition is an azeotropic or near-azeotropic composition comprising: HFC-1234yf (1-80 (preferably 51.5) wt.%) and propane (99-20 (preferably 48.5) wt.%) at 33.5 psi (231 kPa) and -25 degrees C; HFC-1234yf (71-99 (preferably 98.1) wt.%) and n-butane (29-1 (preferably 1.9) wt.%) at 17.9 psi (123 kPa) and -25 degrees C; HFC-1234yf (60-99 (preferably 88.1) wt.%) and isobutane (40-1 (preferably 11.9) wt.%) at 19 psi (131 kPa) and -25 degrees C; and HFC-1234yf (1-99 (preferably 53.5) wt.%) and DME (99-1 (preferably 46.5) wt.%) at 13.1 psi (90 kPa) and -25 degrees C. The azeotropic or near-azeotropic composition is: HFC-1234yf (1-98 (preferably 48.9) wt.%), DME (1-98 (preferably 46.4) wt.%), and n-butane (1-40 (preferably 4.6) wt.%) at 13.15 psi (90.7 kPa) and -25 degrees C; HFC-1234yf (1-98 (preferably 31.2) wt.%), DME (1-98 (preferably 26.2) wt.%), and isobutane (1-50 (preferably 26.2) wt.%) at 14.19 psi (97.8 kPa) and -25 degrees C; HFC-1234yf (1-98 (preferably 16.3) wt.%), DME (1-98 (preferably 10) wt.%), and iodotrifluoromethane (1-98 (preferably 73.7) wt.%) at 15.65 psi (108 kPa) and -25 degrees C; and HFC-1234yf (1-98 (preferably 34.3) wt.%), DME (1-40 (preferably 10.5) wt.%), and bis(trifluoromethyl)sulfide (1-80 (preferably 55.2) wt.%) at 14.57 psi (100 kPa) and -25 degrees C. Preferred Components: The tracer is 83 components e.g. hexadeuterio ethane, octadeuterio propane, difluoro dideuterio ethane, hexafluoro dideuterio propane, tetrafluoro dideuterio ethane, trifluoro trideuterio ethane, 1,1,1,2,2-pentafluoro monodeuterio propane, 1,1,1,3,3-pentafluoropropane, 1,1,2,2-tetrafluoropropane, 1,1,1,2-tetrafluoropropane, 1,1,1-trifluoropropane, 2,2-difluoropropane, monofluoropropane, 1,1,2,2,3,3,4,4,4-nonafluorobutane, 1,1,1,3,3,4,4,4-octafluorobutane, 1,1,2,2,3,3,4,4-octafluorobutane, 2,2,3,3,4,4,4-heptafluorobutane, 1,1,1,2,3,4,4,5,5,5-decafluoropentane. ethane, 1,1,1,2,3,3,3-heptafluoro monodeuterio propane, 1,1,1,2,2,3,3-heptafluo monodeuterio propane, tetrafluoro dideuterio ethane, pentafluoro trideuterio propane, trifluoro dideuteriopropane, difluoro trideuterio propane, hexafluoroethane, cyclo-hexafluoro propane, octafluoropropane, cyclo-octafluoro butane-, decafluoro butane, 1,1,1,2,3,3,3-heptafluoro-2-trifluoromethyl-propane, trifluoromethyl tetramethyl ether, trifluoromethyl pentafluoroethyl ether, trifluoromethyl tetrafluoro ethylether, trifluoroethyl difluoromethyl ether, methyl pentafluoroethyl ether, difluoroethyl trifluoromethyl ether, octafluoropropyl tetrafluoro ethyl ether, trifluoroethane, monofluoro ethane, difluoroethane, tetrafluoroethane, octafluoropropane, 1,1,1,2,2,3,3-octafluoro propane, 1,1,1,2,2,3-hexafluoropropane, 1,1,2,3,3,3-hexafluoropropane, 1,1,1,2,2,3,3,3-octafluoropropane, 1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-pentafluoropropane, 1,1,2,2-tetrafluoropropane, 1,1,1,2,2-pentafluoro propane, 1,1,1,2,2-pentafluoropropane, 1,1,2,2-tetrafluoropropane, 1,1,1,2-tetrafluoropropane, 1,1,1-trifluoropropane, 2,2-difluoropropane and 2-fluoropropane, 1-fluoropropane, perfluoromethylcyclopentane, perfluoromethylcyclohexane, perfluorodimethylcyclohexane (ortho, meta, or para), perfluoroethylcyclohexane, perfluoroindane, perfluorotrimethylcyclohexane or their isomers, perfluoroisopropylcyclohexane, cis-perfluorodecalin, transperfluorodecalin and cis- or trans-perfluoromethyldecalin or their isomers. The compatibilizer comprises: (a) polyoxyalkylene glycol ether compounds of formula (R1((OR2)xOR3)y) (i), where (i) have a molecular weight of 100-300 atomic mass units; (b) amide compounds of formulae (R1C(O)NR2R3) or (cyclo-(R4CON(R5))) (ii), where (ii) have a molecular weight of 100-300 atomic mass units; (c) ketone compounds of formula (R1C(O)R2) (iii), where (iii) have a molecular weight of 70-300 atomic mass units; (d) nitrile compounds of formula (R1CN) (iv), where (iv) have a molecular weight of 90-200 atomic mass units; (e) chlorocarbon compounds of formula (RClx) (v), where (v) have a molecular weight of 100-200 atomic mass units; (f) aryl ether compounds of formula (R1OR2) (vi), where (vi) have a molecular weight of 100-150 atomic mass units; (g) 1,1,1-trifluoroalkane compounds of formula (CF3R1) (vii); (h) fluoroether compounds of formula (R1OCF2CF2H) (viii) or where (viii) are derived from fluoroolefin compounds and polyol compounds; (i) lactone compounds of formula (B), (C) or (D), where the molecular weight of (B), (C) or (D) is 100-300 atomic mass units; and (j) ester compounds of formula (R1CO2R2) (ix), which have a molecular weight of 80-550 atomic mass units. The stabilizer is nitromethane, hindered phenols, hydroxylamines, thiols, phosphites or lactones. The solubilizing agent comprises the compounds (a)-(i). The fluoroolefin compounds are of formula (CF2=CXY1) (viiia). The polyol compounds are linear polyol compounds of formula (HOCH2CRR1(CH2)z(CHOH)xCH2(CH2OH)y) (viiib) or the branched polyol compounds of formula (C(OH)t(R)u(CH2OH)v((CH2)mCH2OH)w) (viiic). In formula (i):x = 1-3;y = 1-4;R1 = H or 1-6C-aliphatic hydrocarbon radicals, where y is bonding sites;R2 = 2-4C-aliphatic hydrocarbylene radicals; andR3 = H, 1-6C-aliphatic hydrocarbon radicals or 1-6C-alicyclic hydrocarbon radicals, where at least one R1 and R3 is the hydrocarbon radicals.In formula (ii):R1, R2, R3, R5 = 1-12C-aliphatic or alicyclic hydrocarbon radicals, where at most one aromatic radical have 6-12C; andR4 = 3-12C-aliphatic hydrocarbylene radicals.In formula (iii):R1, R2 = 1-12C-aliphatic, -alicyclic or -aryl hydrocarbon radicals.In formula (iv):R1 = 5-12C-aliphatic, alicyclic or aryl hydrocarbon radicals.In formula (v):x = 1 or 2; andR = 1-12C-aliphatic or alicyclic hydrocarbon radicals.In formula (vi):R1 = 6-12C-aryl hydrocarbon radicals; andR2 = 1-4C-aliphatic hydrocarbon radicals.In formula (vii):R1 = 5-15C-aliphatic or alicyclic hydrocarbon radicals.In formula (viii):R1 = 5-15C-aliphatic, alicyclic, or aromatic hydrocarbon radicals.In formula (viiia):X = H, Cl or F;Y1 = Cl, F, CF3 or ORf; andRf = CF3, C2F5 or C3F7.In formula (viiib):R, R1 = H, CH3 or C2H5;x = 0-4;y = 0-3; andz = 0 or 1In formula (viiic):R = H, CH3 or C2H5;m = 0-3;t, u = 0 or 1; andv, w = 0-4, where t+u+v+w = 4.In formulae (B)-(D):R1-R8 = H, linear or branched, cyclic or bicyclic, optionally saturated hydrocarbyl radicals.In formula (ix):R1, R2 = linear or cyclic, optionally saturated, alkyl or aryl radicals. EXAMPLE - Typical composition comprised of (in wt.%): 1,2,3,3,3 -pentafluoropropene (25); 2,3,3,3-tetrafluoropropene (73); and difluoromethane (2).