Patent GB-839351-A (GB)
Title: Improvements in and relating to condensers and the promotion of dropwise condensation of vapours
Inventor: DEWAR MICHAEL JAMES STEUART
IPC: C07F7/08
Filed: 1955-03-29
Abstract: Copper or copper alloy condenser surfaces are treated to promote dropwise condensation of water vapour thereon by applying to the surface a promoter consisting of a compound containing one or more polar groups, each comprising a sulphur or selenium atom, directly attached to one or more unsubstituted open polymethylene chains containing at least 10 carbon atoms, any two such polar groups present being separated by such chain, the said sulphur or selenium atom having free valency electrons available whereby the compound is bound to the metal condenser surface, the compounds being free of any other polar groups.  The compounds may be applied by immersing the surface in or painting it with a solution of the compound in a volatile organic solvent, and this may be effected before assembly of the condenser; alternatively, the solution of the compound may be injected in the steam being condensed on the metal surface.  A film of the compound which is believed to be mono-molecular forms on the surface.  The promoters may be alkyl xanthates, thioxanthates, thiocyanates, acetodithio carbamates, thiol carbamates, seleno cyanates, thiotic esters, thiols, sulphides, thiosilanes or thiophosphates and many examples of each class are given.  Tests are described wherein steam is condensed on an internally cooled brass tube or in ships' condensers, the surfaces being provided with a film of: 1 : 10-decane dipotassium dixanthate, S-ethyl - O - octadecyl xanthate, di - O - octadecyl - SS - 1 : 10 - decane dixanthate, didodecyl trithiocarbonate, didodecyl decane dithiolate, dodecyl 11-seleno cyanato undecane thiolate, octadecyl thiocyanate, octadecyl seleno cyanate, octadecyl aceto-dithiocarbamate, octadecyl thiol carbamate, octadecane thiol, 1 : 10 - bis - (dodecane thio) decane, tetrakis - (dodecane thio) silane, dodecane tris-(ethane thio) silane, tridodecane phosphoro trithioite, tetrakis - (dodecane thio) phosphoro trithiolate, O,O - dioctadecane hydrogen phosphorothiolothiolate, tetra - octadecoxy phosphoro trithioic anhydride and dodecane thiol. The preparation of many such compounds is described (see Group IV (b)).  Some of the thiosilanes and xanthic esters form part of the subject - matter of divisional Specifications 839,352 and 839,353.ALSO:Organic sulphur or selenium containing compounds, most of which are said to be novel, for use in treating a copper or copper alloy condenser surface to promote dropwise condensation of steam thereon (see Group XIII), are prepared as follows : (1) S-benzyl O-octadecyl xanthate by reacting ethyl bromide with potassium octadecyl xanthate in ethanol; (2) di-dodecyl trithiocarbonate by reacting dodecanethiol with thiophosgene in CS2; (3) ethyl dodecyl trithiocarbonate by reacting dodecanethiol with ethyl dithiochlorocarbonate in CS2; (4) dodecyl octadecane thiolate by reacting dodecane thiol with octadecanoyl chloride; (5) di-dodecyl decanedithiolate by reacting decanedioyl chloride with dodecanethiol; (6) 1,10-bis-(octadecanoyl thio)-decane by reacting octadecanoyl chloride with 1,10-decane dithiol; (7) dodecyl 11-dodecyl thioundecane thiolate by reacting dodecyl 11-bromo undecane thiolate with an alcoholic solution of dodecane thiol containing a little of the sodium thiolate; (8) decylene bis-(11-dodecyl thio-undecane thiolate) by similarly reacting decylene bis-(11-bromo-undecane thiolate) with dodecanethiol; (9) dodecyl 11-mercapto-undecane thiolate by reacting dodecyl 11-bromo-undecane thiolate with thiourea in ethanol followed by treating the product with alcoholic NaOH; (10) decylene bis-(11-mercapto-undecane-thiolate) by similarly reacting thiourea with decylene bis-(11-bromo-undecane-thiolate) and hydrolysis of the product; (11) 1,10-decane-dithiocyanate by reacting 1,10-decane-dibromide with KCNS in ethanol; (12) dodecyl 11-thio-cyano-undecanethiolate by similarly reacting the 11-bromo compound with KCNS; (13) decylene bis-(11-thiocyano-undecanethiolate) by similarly reacting the decylene bis (11-bromo) compound; (14) tetrakis-(dodecanethio)-phosphoro-trithio anhydride by reacting thio-pyrophosphoryl tetrabromide with excess sodium dodecane mercaptide in ether; (15) tridodecane phosphorotetrathioate by reacting phosphorus thiochloride with excess sodium dodecane mercaptide in ether; (16) O,O-dioctadecane hydrogen phosphorothiolothionate by heating octadecanol (4 mols.) with P2S5 in toluene; (17) O,O,S-tri-octadecane phosphorodithioate by reacting octadecanol (6 mols.) with P2S5 in toluene; (18) tetraoctadecane phosphorotrithioic anhydride by reacting thiopyrophosphoryl tetrabromide with octadecanol in the presence of pyridine in toluene; (19) dodecyl 11-carbamoyl thio-undecane-thiolate by treating the 11-thiocyano compound with ice-cold sulphuric acid; (20) decylene bis-(11-carbamoyl thioundecanethiolate) by similarly treating the bis-(11-thiocyano) compound; (21) octadecyl thiol carbamate by similarly treating octadecane thiocyanate; (22) 1,10-decane di-thio-carbamate by similarly treating 1,10-decane di-thiocyanate; (23) dodecyl-[11-(N-acetyl thio-carbamoyl thio)-undecane-thiolate] by refluxing the corresponding 11-thiocyano compound with excess thio-acetic acid; (24) decylene bis-[11-N-acetylthio-carbamyl thio)-undecane-thiolate] by similarly treating the corresponding bis-(11-thiocyano) compound; (25) octadecyl aceto-dithiocarbamate by refluxing octadecyl thiocyanate with excess thioacetic acid; (26) 1,10-decane di-acetyl-dithio-carbamate by similarly reacting the 1,10-di-thiocyanate; (27) octadecyl thiododecane by reacting octadecyl bromide with sodium dodecanethiolate in alcohol; (28) 1,10-bis-(dodecane-thio)-decane by similarly reacting the thiolate with 1,10-decanebromide; (29) dodecyl 11-selenocyanato-undecanethiolate by reacting dodecyl 11-bromo-undecanethiolate with KSeCN in alcohol; (30) decylene bis-(11-selenocyanato-undecanethiolate) by similarly reacting the bis-(11-bromo) compound with KSeCN; (31) octadecyl selenocyanate by similarly reacting octadecyl bromide with KSeCN; and (32) 1,10-decane diselenocyanate by similarly using the decane dibromide.  Dodecyl 11-bromo-undecanethiolate used in (7) and (9) is prepared by reacting 11-bromo-undecanoyl chloride with dodecanethiol. 1,10-Bis - (o  - bromo - undecanoyl - thio) - decane used in (8), (10) and (13) is prepared by reacting 11-bromo undecanoyl chloride with 1,10-decane-dithiol.  The Provisional Specification includes the preparation of additional analogous dropwise condensation promoters: (33) potassium octadecyl xanthate by interaction of the alcohol, KOH and CS2; (34) 1,10-decane di-potassium xanthate by similarly reacting the decane-diol; (35) di-dodecyl oxalodithiolate by reacting dodecane thiol with an ice-cold solution of oxalyl chloride and pyridine; (36) dodecyl ethane-thiolate by reacting dodecanethiol with acetic anhydride in the presence of sodium acetate; (37) octadecyl thiocyanate by refluxing octadecyl bromide with KCNS in alcohol; (38) octa-decanethiol by reacting octadecanol with thio-urea in aqueous HBr and hydrolysing the product; (39) 1,10-decanedithiol by similarly reacting the decane-diol; (40) di-dodecane di-sulphide and di-octadecane disulphide by oxidizing the corresponding thiols with H2O2; (41) di-octadecane sulphoxide by oxidizing the corresponding sulphide with 50% HNO3; (42) tridodecane phosphorotrithioite by reacting PCl3 with excess sodium dodecane mercaptide in ether; and (43) tri-dodecane phosphorotrithiolate by similarly reacting POCl3, most products of which are said to be novel.  Specifications 839,352 and 839,353 are referred to.