Výroba dalších významných monomerů isokyanáty, k.benzoová, epsilonkaprolaktam, trinitrotoluen, bisfenol A, epichlorhydrin, monomery PET
POLYURETANY (PUR)
Vznik isokyanátu
Vznik uretanu R-NH2 + COCl2 isokyanát
R-N=C=O alkohol
R-N=C=O + HO-R
R-NH-CO-O-R
URETANY = ESTERY KYSELINY KARBAMOVÉ H-O-C-NH2 O
Reakce uretanů – látky s aktivním vodíkem R-NCO + H2N-R*
R –NH-CO-NH-R* ALKYLOVANÉ MOČOVINY
R-NCO + H2O
R-NH2 + CO2
REAKCÍ S VODOU SE UVOLŇUJE OXID UHLIČITÝ
Základní reakce isokyanátů
Technicky důležité polyisokyanáty
Hexamethylendiisokyanát OCN-(CH2)6-NCO
}
{ rozmanitost
diizokyanáto dicyklohexylmethan
2,4 – toluen diisokyanát
4,4′ -diisokyanatodifenylmethan (kondenzace anilinu a formaldehydu)
Vznik polyolů polyetheralkoholy, polyesteralkoholy (propylenoxid, ethylenoxid + voda, alkoholy, dioly) CH2
CH2
+ HO-CH2-CH2-OH
O HO-CH2-CH2-O-CH2-CH2-OH dikarboxylová kyselina + přebytek diolu
Polyesteralkoholy O H3C O C
O C O CH3
O
-2 CH3OH
HO CH2CH2 O C
+
HO CH2CH2 OH
O C O CH2CH2 OH
Tolylendiizokyanát – hlavní monomer pro výrobu polyuretanů 1. Nitrace toluenu na dinitrotoluen 2. Hydrogenace dinitrotoluenu na toluendiamin 3. Fosgenace na tolylendiisokyanát Fosgen vzniká slučováním oxidu uhelnatého s chlorem při trplotě od 130 °C do 150 °C z přítomnosti katlyzátoru, kterým je aktivní uhlí nebo houbovitá platina CO + Cl2 → COCl2
Výroba TDI a MDI
Nitrace toluenu TOLUEN + NITRAČNÍ SMĚS (HNO3+H2SO4) Mírné podmínky, obsah vody v nitrační směsi až 23 %, získá se směs tří izomerů, 63% ortho, 34 % para, 4 % meta Dělení destilací nebo krystalizací Další nitrace směsí o- a p- dává směs 2,4- a 2,6dinitrotoluen
Hydrogenace směsi dinitrotoluenů na toluendiaminy • Redukce v methanolovém roztoku s Raneyovým niklem (palládiem) při teplotě cca 100 °C a tlaku 5 MPa • Série tlakových hydrogenátorů..selektivita až 99 %
Výroba TDI a MDI
Fosgenace 1. krok: studená fosgenace Reakce primárních aminů s fosgenem v rozpouštědle (dichlorbenzen) při 0 až 50 °C za tvorby karbamidchloridu a hydrochloriduaminů 2. krok: horká fosgenace 170 °C až 180 °C …reakce s dalším fosgenem..diisokyanát
Výroba TDI a MDI
Výroba TDI
Výroba 4,4´- difenylmethandiisokyanátu MDI 1. krok: kondenzace anilinu s formaldehydem 2. krok: fosgenace 4,4´- diaminodifenylmethanu
Variantní – méně rozšířené technologie – bez fosgenu
Světové výrobní kapacity TDI
Světové výrobní kapacity MDI
MDI…4,4’-difenylmethandiisokyanát 1. Kondenzace anilinu s formaldehydem 2. Fosgenace na MDI
Další významné diisikyanáty
Hydrogenovaný MDI
Kyselina bonzoová
Hlavni použití je ovšem pro výrobu fenolu
Trinitrotoluen
Nitrace To increase the NO2 + content (3 wt % in pure HNO3), lower the solubility of end products, reduce oxidative side reactions, and facilitate the treatment of spent acids, mixtures of sulfuric and nitric acids (mixed acid) are used. The water content of a mixed acid may be reduced by adding oleum. In 50: 50 wt% mixed acid, the nitric acid is ca. 15 % dissociated. However, sulfuric acid is dificult to remove
Moderní nitrace More recent nitration methods useN2O5 as a solution in pure nitric acid (“nitric oleum”) or in chlorinated solvents (e.g., CH2Cl2). Three processes for the production of nitric oleum are in operation or in development : 1) Oxidative electrolysis of a N2O4 –HNO3 mixture 2) Ozonation of N2O4 3) Distillation of an oleum (H2SO4 +SO3) – NH4NO3 mixture
Nitrace Nitration. Reaction is exothermic. Dilution of the nitric and mixed acids with water liberates heat [52]. Normally, nitration is rapid. However, 70 – 85wt % nitric acid is also an oxidant, and for this reason the reaction is best conducted continuously to limit the contact time of the product with the reactive medium. If the medium is free of solid particles, a tubular reactor can be used; otherwise, reactors in cascade with efficient stirring are employed. These reactors are made of highly polished stainless steel.
Nitroaromatické látky jako expolziva Three nitroaromatic products with a picryl group remain for use as high explosives: TNT, HNS, and TATB. 2,4,6-Trinitrotoluene [118-96-7], TNT, tolite, C7H5O6N3,Mr 227.13 (1,R=CH3), is produced by successive nitration of toluene, producing mono-, di-, and .nally trinitrotoluenes. The mononitration products are 60 % ortho, 35 % para, and 3 – 5 % meta derivative.
TNT Uvolnění vody !
Kaprolaktam
Monomery pro výrobu epoxidů
Reakce dianu (bisfenolu A) s epichlorhydrinem
VÝROBA BISFENOLU A FENOL + ACETON
BISFENOL A
PRINCIP REAKCE Sulfonated cross-linked polystyrenes [372] , [377][378][379] are used as the catalyst which are usually arranged as a fixed bed over which the reaction mixture is passed. The reaction of phenol with acetone takes place at 50 – 90 °C, the molar ratio phenol – acetone is up to 15 :1.
Epichlorhydrin 1. Vysokoteplotní radikálová substituce 2. Adice k.chlorné
3. Eliminace chlorovodíku (vápenné mléko)
Kyselina tereftalová, dimethyltereftalát
OXIDACE P-XYLENU COOH
CH3 + O2 CH3
COOH NEČISTOTOU JE K. FORMYLBENZOOVÁ ČISTŠÍ PRODUKT: OXIDACE NA DIMETHYLTEREFTALÁT P-X + O2 …PMB + CH30H…METESTER PMB+O2…+CH3OH.. DMTF
Oxiace p-xylenu v kapalné fázi. Směs p-xylenu, vzduchu, k. octové a katalyzátoru (soli kobaltu a manganu) je dávkován do reaktoru při teplotě 175 až 230 °C a tlaku 2 až 3 MPa, kde se zdrží 0,5 a 3 hodiny. Vzniklá suspenze je ochlazena, kyselina tereftalová se odstředí (krystalická látka), promyje a vysuší.
VÝROBA K.TEREFTALOVÉ
A feed mixture of p-xylene, acetic acid, and catalyst is continuously fed to the oxidation reactor (Fig. (1)). The feed mixture also contains water, which is a byproduct of the reaction. The reactor is operated at 175 – 225 °C and 1500 – 3000 kPa. Compressed air is added to the reactor in excess of stoichiometric requirements to provide measurable oxygen partial pressure and to achieve high p-xylene conversion.
VÝROBA K.TEREFTALOVÉ
Catalytic, liquid-phase oxidation of p-xylene to terephthalic acid by the Amoco process a) Oxidation reactor ; b) Surge vessel ; c) Filter ; d) Dryer ; e) Residue still ; f ) Dehydration column
VÝROBA K.TEREFTALOVÉ
Purification of terephthalic acid by the Amoco process a) Slurry drum ; b) Hydrogenation reactor ; c) Crystallizers ; d) Centrifuge ; e) Dryer
VÝROBA DIMETHYLTEREFTALÁTU
Fresh and recovered p-xylene, along with catalyst (mostly cobalt with some manganese) are combined with methyl p-toluate and fed to the liquid-phase oxidation reactor. Because bromine and acetic acid are not used, vessels lined with titanium or other expensive metals are not necessary. Oxygen supplied by compressed air is added at the bottom. Oxidation conditions are 140 – 180 °C and 500 – 800 kPa. The heat generated by oxidation is removed by vapors of unreacted p-xylene and the water of reaction. Cooling coils in the reactor are used to generate steam. The steam and reactor vapors are condensed and combined to recover p-xylene for recycle.
The oxidation effluent is then heated and sent to the esterification reactor, operated at 250 °C and 2500 kPa. Excess vaporized methanol is sparged into the esterifier, where the ptoluic acid and monomethyl terephthalate are converted noncatalytically to methyl p-toluate and dimethyl terephthalate, respectively. Overhead vapors from the esterification reactor are condensed and fed to a distillation system, where the water from the esterification is separated from methanol, which is recycled. The remainder of the process separates the dimethyl terephthalate from methanol and methyl p-toluate, which are recycled, and residue and wastewater, which go to waste treatment.
The product from the esterifier goes to an expansion vessel. Vapor from this vessel feeds a methanol recovery column, where the methanol overhead goes to methanol recovery, and the methyl ptoluate bottoms are recycled to the oxidation reactor. Liquid from the expansion vessel feeds two vacuum distillation columns in series, which yield crude dimethyl terephthalate. The first column recovers more methyl p-toluate overhead for recycle to oxidation, and the bottoms feeds the crude dimethyl terephthalate column, where the product is taken overhead. The bottoms from the dimethyl terephthalate column, containing heavy byproducts and catalyst metals, can be mixed with water from the oxidation, which dissolves the catalyst. The resulting slurry is centrifuged ; the catalyst solution is recycled, and the cake is sent to disposal.
