Green Technology and Green Chemistry PDF

......... ~.... I I Green Technology _and Green Chemistry "Green Chemistry represents the pillars that: hold...

......... ~.... I I Green Technology _and Green Chemistry "Green Chemistry represents the pillars that: hold up our sustainable future. It is imperative to teach the value of green chemistry to_tomorrow's chemists". · Daryle Busch Objectives 1 Introduction Green Technology.. , 1 Green Chemistry ~d it~ Basi~ Principl~s. 1 , r Concept.of Atom Economy ·.·. ,".. 1 1 Tools of Green. Chemistry 1· Zero waste technology 51~- INTRODU.CTION.. -.... --- Chemical Manufact uring has brought revolution in the life on earth. It is the source of many useful products like drugs, antibiotic s, plastics, fuels (like gasoline), agricultur al chemicals (like pesticides and ~nsecticides, fertilisers; synthetic fabrics (like nylon, rayon, polyesters) and many others. The ill effects of the chemical industries are also not less in magnitud e. The re~ipient of the ill effects is not only man but also the environm ent. The alarming increase in the level of pollution forced the governme nts all · over the world to make laws to minimize it. This gave rise to the birth of th Green Technology and Green Chemistry by the middle of 20 centµry. Green chemistry is environm ent friendly chemical synthesis in whi~h schemes are designed in such a way that environm ent pollution is minimized. It is based on this age old principle "Prevention is better than cure". In this field, attempts are made to prevent wastes during chemical synthesis so that later cleaning up the environm ent does not become a problem. Here the starting materials,' solvents, catalysts etc. are so chosen that they. have no or minimum toxic effects on the environm ent. For ~stance the use of Benzene, Toluene etc. are discourag ed as. solvents smce they are carcinoge nic in nature. If possible, the reactions are carried out in the aqueous phase. Thus, alternate methods of chemical synthesis d~v~loped in Green Chemistr y should ·be applied to the maximum to IIllnnnize· the ill effects of pollution. I 115 [ 116 Tex tboo k of Env iron men tal Stud ies 5 ·2 GR ~~ N TE CH NO LO GY · frie ndl y ~e ne ve r the ter m" Gre en" is use pra ctic al. 0 ~ec ts and "Te chn olo me ans the a lica tion of kno wle dge for e ree n new me tho o ogie s enc pur po~ es. Sin ce Gre en Che mis try invo lves sam e in the bro ade r sen se. The Ch em istr y or Tec hno log y me ans the ed in det ails in C~ apt er 1 Ufider con cep ~s of Gre en Tec hno log y is des crib Gre en Tec hno log y · the top ic 'Int rod uct ion of the con cep t of iNCIPL.E S 5.3 GR EE N CHEMISTRY AND ITS 'iiA~IC P.R : wa rne r, "G ree n che mis try or As def ine d by Pau l T. An asta s and J.C des ign of che mic al pro duc ts ent ally ben ign che mis try is the env iro nm ina te the use. a nd. gen era tio n of and pro ces ses tha t red uce or elim g fiel d has g~n cd imp orta nce not haz ard ous sub sta nce s". Thi s eme rgin th e wo rld of bot h elo pm ent but in onl y in the are as of res ear ch and dev aca dem ics and ind ust ry. Bas ic Pri ncip les of_Gre en Che mis try vi~ us s~c tion ). bas i_ca lly a~m s at Gre en C~ em i~tr y (de fine d i~ the pre inv olv ing van ?us u~n ova tion s in red uci ng the env iron me nta l pol luti on by pub lica tio Joh n Wa rne r in the ir the che mic al syn the sis. Pau l An asta s and. "h d ctic e. ave.eve lop ed 12 n d, Gre en Che mis try: "The o1:Y ~d Pra ( 199 8) title deh nes for che mis ts for dev elop in prin cip les (giv en in the box) to give gui · g , Gre en Ch em istr y. · · ed belo w: · Th e Tw elve Bas ic Prin cip les are Exp lain · ·. , ·. d\ Pre ven tion of Waste.r~a ctio n. ~o~ stit ute th~ was te. The UJ · Th~ by- pro duc ts for me d in a che mic ai y or ma y not be haz ard ous ) als unr eac ted sta rtin g ma teri als (wh ich ma the sis sho uld be des ign ed in sue~ for ms par t of. the was te. Che mic al syn a wa y tha t the wa ste pro duc ts min imi zed. Thi s is 1?e cau se sometimes are om es so "exp ens ive tha t it adds the cle ani ng and dis pos al of wa ste bec tio n cos t. By pre ven tio n of waste tre me ndo usl y to the ove rall pro dnc h as haz ard s ass oci ate d wit h waste gen era tion , the ass oci ate d pro ble ms.suc is min imi zed. · sto rag e, tran spo rtat ion and tre atm ent (i} At~,;; Ec~no~~tj - ~ ·~ ~ · ed to ma xim ize the inc orp ora tion of Che mic al Syn the sis sho uld be des ign the, sta rtin g ma teri als _and rea gen ts in the fin al pro duc ts. Thi s concept epa rat e section of.. Tro st is des crib ed in 5rt ail in a ,s developenventional method, Benzyl chloride (a known hazard) t,e d as the protecting group for "OH" group~·, The waste ·generated after 1s u~:protection should be _hct?~led properly~ This reaction is also less atom. we -.ical since a lot of waste is generated. · - - - ·. rr eCono,lJ.A..: '....--- ~- - , -.. -......... ~~. a.o I CHO · C6HsCH2Cl ~6.lisCH201drCH O (OJ.V (Benzyl chloride) ~ M-benzyl ether td-bydrX}' b~nzaldehyde · benzaldehyde J.. a cH o~COOH HO~COOH C6n5. 2 ,...... :::::-... l I HCl 0.+ Benzyl aleen"l.. ,_ M-Benzyl ether M-Hydroxy ~ benzoic acid · · benzoic acid · '. ' ·.IJ~/2)· ~ ~ -y_-:;.-.3 ·. f use of Catalysts ~.nd No~-Stoichiom~ eagents......... Th waste is minimized. i( the catalytic reagents ~re used since_ the. cat:lytic rea_c ~ions ?-re highly· specifif chemicals in a reaction,. tlie unr.eac ed reagents (chemicals ) should be recycled. {[9 Design of Manufacturin~ Plants to Minimiz~.the / · Potential for Accidents The chemicals and· their forms (solid, liquid, or gas) should be chosen to minimize the potential for not only the chemical accidents but also explosion s, fires and release of toxic substance s to the atmospher e. A number of accidents have been found to occur in industrial units for example the infamous Bhopal Gas Tragedy (December 1984)*, resulted not only in loss of thousand s "of human lives but also left n:i,any people in the next generation disabled. 4- , (J::t:.W..t.; b oOl-ait.Lr-0.. CASE STUD Y. The Bhopal Gas ~ak Disaster.. On ·oecembe r 3, 1984, disaster struck Bhopal, the capital city o: the state of Madhya Pradesh located in Central India. The · ·union Carbide Factory involved in the ·m anufactur e of carbamat e type -~ of pesticide used Methyl iso-cyana te (MIC). as a intermedi ate produ·c t. ~Du¢" to 't he. ·~eged functional failure of "vent '.scrubber " outlet, 30 to~es of a potentially toxic, methyliso cyanate  - · Green Technology and Gr~e~. , Che~1stry 121 -. cap ed from the · und erg rou n d stor age tank s 'of the pes tici de gas.es turi ng plan t. As a con e were nea rly 250 0 dea ths · rne.nufac d' bil'ty f' seq uen ce ther survivors... and sever~ 1sfa Mlle O mor e _th~ 1,00 ,000 ses vom if1~g, ·Vlo.· 1ent coughing, suff oca tion. , · J alat 10n o cau · I~,.h , · ,· r. ' 1.. the lung s, PWmbnAn, di d ers,, carl.W...1:...: 1c:w ,-_:, · oval of oxy gen 1ro? h k ' sor :lc ure, rern d t0 8 -J in the eyes cau sed eye and dea ~ ue. c ?. ?g. urn ing sen sati on 1 dne ss in the surv ivor s. illfection~ (conJunct~~t~s) and eve ntua l blin rbe surviv?~s wer e dts~bled not merely for a lifetin ie but everi beyond, on the disabilities to the because sen o~s · gen etic_effec~s would pas s. ·. ture gen~r~tions as ~el l.. ·. · d to~ ~ds the end of fuit is inde ed iron ical tha t the disa ster occ~rre bid e f:,iinited and the tbe Golderi Jub ilee ,' cele brat ions of Union ·C~ wet towc,J cou ld ~v e ~1111pJe pr~~aution of ~re_a thin g thio ugh a , : ·_. ·.. saved so ·m any. Uv:es~. example of ~ i.J:iqustrial _ This 'wo rs! eve r disa ster in:B hop ~ is.a n ,pollution aGCI~~nt._c~~~ed du~ ~o il1:~ _faµu re ~ llanc;lling a _toxic ~at eria l_ in ·1arge.:sc a)e' ch~ m1c ~ proc essi ng. l ,, :. ' '... ,... , ·,., ' ·, -.. '. " 1 i.. ; f t...... ~... ~ ' CHEMIST~X/TECHNOLO~Y'S SOME OF THE FINEST EXAMPLES OF GREE~. · _,., · _ _,.. ·.. · ACHIEVEMENTS ARE AS FOLLOWS 1. Barty fros t's con cep t of Atom Economy f~ expi-es~ing tqe effjciency of..... a reaction (dis cus sed in section 5.4) ·~-- -- · ~ · - 2. New Syn thes is of Ibuprofen. age nt inst ead of CFC 's fo: 3. Use of was te carb on dioxide as a blowing foam poly styr ene syn thes is. clea ning.. 4. Development of CO2 as a solvent for dry de in the s. Development of oxi dan t acti vato rs for hyd rog en pe_roxi man ufac ture oi pap er. 6. Development of new insecticides. ,.,, ~ ,. r··.. -.... f;· · 5.4 CONCEPT.OF ATOM ECONOMY · ""II _,..,.._....J,.,;i/r,,;t..,_,.,. ,. ,. ~ ,.... l.,'\ ~ { ,. :,, - [ ~- h,I,; ·- by Bar ry Tro st in 199 1 which The concept of atom eco nom y was developed a par ticu lar reae,:tion in whi~h is a method of ex ress in the efficienc of e mai n ired m pro uc. reactari atom s are inco rno rate d into the des met hod olog y or des ign a new objecttVe of this con cep t is td develop a new ms becoroe iucarporated into synthesis in whi ch mos t of the.r eac tant ato. If was te or the by p~o duc ts:.,,. the ~al desi red procf.uct thu s redu cing the ulat ed by: he percentage yield of any reac tion is calc Act ual yield of the pro duc t x 100 { · 0 1/o yield =... _Theoretical yield of the pro duc t A reaction may hav e a perc enta ge in yi~l d of 100 % but may not be s of by-p rod ucts are obta ined. ;Typcon~idered as grse n syn thes is ifJarge amo unt u;ve a yiel a of ICal ~xamples are Gri gna rd. and Witting reac tion s whi ch o· loOo/c0 alongwith larg. e amo unt of by- pro duc ts. For a reac tion to be considered ,. ' J..  "...9 - - - '.... - - - 122 Textbook of Envir:onmenta.) Studies as gre.en synthesi~,. the percentage of ~tom economy is calculated by the followmg equation. · / Mass of atom in desired products L/' % atom economy =. x 100. Mass of atoms m reactants Let us consider some common reactions and find which has more percentage of atom economy. , " -~angeme nt Reactions · ·. ( \_./'Allyl phenyl ether gives 0-Allyl phenol by h~ating at 200°C. CH O. CH......._ OH H~ 'c-/ '------cH2 200°c Hc-7 c/ CH2 - 1 II I ---- I II 11 HC~ ,....-CH ~CH Rearrangement HC~ ,....-C......._ ,....-CH CH H2C CH CH2 Allyl phenyl ether O-Allyl phenol (M.W = 134.175 g) ~, (M.W. = 134.175 g) " }desired product) 134.175 F % Atom economy= _ x lOp 134 175 = 100. ,,, This is a 100% atom economical reaction. ~ i o n Reactions ~ Cycloaddiµon reactions of Butadiene to Cyclohexene 82 % Atom economy= x 100 82 = 100 ~CH2. CH I -.+ CH~ CH2 Butadiene Ethene [M.W. = 54 g] [M.W. 28 g). Cyclohexene [M.W. 82 g) (desired product) (b) _.,ehlalytic add~tion re~ ~ / Ni H3C-CH=C H2 + H2 - - - CH3-CH2-CH3 Propene Propane (M.W. 42 g) (M.W. 2 g) [M.W. =44 g) (desired product) - -·.. 44. % Atom economy= - x 100 = 100 ·. 44. Since Ni is used as a catalyst, it can be recovered fully after·the reaction. Thus both type of addition reactions give an atom economy of 100%.  r ·d G · - 12 3 Green Technolo.gy ·a_n_, !,8~!1 Ch emistry , j ~· - · 4 · ·-· ··: -- ·tutfon Reaction 511t>st1 ti f M eth yl ns id er a su bs tit ut io n re a c on o Et hy l pr op io na te wi th o e 0 - i,.r l II ·. p s + H3 C~ NH 2 cf l3.....: :c H2 -C -O -C 2H Eth yl pro pio nat e Methyl am ine (M.W- = 102.132 g) (M.W. = 31.057 g) ~. H 2 + C2 Hs OH C H 3- C H 2- C -C H2 -N M.W. 40.083 g ·. : _. (de sire d pro duc t) M.W. = 87.106 g 87-10 6 x 10 0 % At om ec on om y= 57 · 10 2. 13 2+ 31.0 = 87.1 06 X l0 0 13 3. 18 9 = 65.4 0 I. Reacti~.~ , 0 idation ma lei c an hy d · ln ve rs io n of Be:112ene to ,::::::-0 C. c.....,... "- + 4. 5 02 II o c, / Be nze ne (M.W. = 78 g) (M. W. = 144 g) - c~ 0 Ma leic anh yd rid e (de sire d pro duc t). (M.W. = 96 g) -. -- + x 10 0 % At om ec on om y = 78 14 4 = 43. up ro fe n. nt ex am pl e of at om ec on om y is th e sy nt he sis of Ib A very im po rta ed six ste ps wi th an at om ec on om y of ju st us The co nv en tio na l m et ho d ed a ne w th re e sta ge pr oc es s wi th an C de ve lop 40.1 %. In th e l 99 0s th e HC mm er cia l m et ho d. Th is re ac tio n wo n th e , no w a co atom ec on om y of 77~4% Aw ar d in 19 96 in U. S. A. ist r;1 Ch all enge Presidential Gr ee n Ch em ":\~~~~-~~..,..,_--,..\»I:,.,. ,,..,~_\.,,,_ '-':V ~~~ - R~( -~ ~.,,: :...~~-, -~·-,·:_..:~2:~:~~ , "~ ts.-.........-,...,.....-.. ,:., &~~ ~fPJ;~ Q f ~~1 - =.~N. Q~E~l~! ty in th e is to re du ce. th e to xi ci ee n ch e.m is try Th~ ob jec tiv es of gr th e ne w ar ea s ha ve to be fo un d wh er e r to ac hi ev e th is, ~nVIronment. In or de e$ e ar ea s se rv e as 'to ol s' fo r Gr ee n ca n be m ad e. Th ~~pro_vements ist ry ) ar e as Th e id en tif ied ar ea s (i. e. to ol s of Gr ee n Ch em 11 ell lis by. fiOu ows:..  124 Textbook of En~ronmental Studies Tools of Gree n Che mist ry I l l ·l l / aterials Gree n Star ting ?:::¢ ·R/ R / s Green Green Chem ical Products Green Methodologies / ,..--- GREEN STARTING MATERIALS The star ting mate rial is said to be green whe n it is non toxic, prefer bl renew~ble and does not degrade the quality ~f the acid whi ch is an imp orta nt chem ical used m the envi ronm ~t*. synt hesi s of nyl pie.Y Adf plas ticis ers and lubr ican ts is conventionally prep ared. from benzene-:-:-,;...., wi:onh, car_cmogenic. -. 1s An- - envi ronm enta lly b emg. n synthesis. Of UlC Ad ~ acid is from D_-glucose (a nontoxic and renewable sour ce an solvent used is wate r mst ea o organig solvents. - ~ f ~n ii. ;n al sii,; thes ls ofAdl plc Aci dO 0 Benz ene Ni~: Pt.. Cyclo O.. hexan.. e Ca:y,t 6 Cyclohexanone + 6 Cyclo hexan ol Cu, NH4i l03 l HN03 \, }fO O c.. -\~2-)~- C/JOfj N2 0 + CO OH ~C OO H Adipic acid ~~hesis oiAdlplc Acid from D-Glucose COOH D-Glucose E. Coli (genetically A (1 altered) HO ~ HO ~ OH OH PCA Catec hol (Protocatechoic acid) l COOH CO OH ~C OO H H2IC at COOH F" =1  + CJf_sc.t ~ 0 Green Tec hno l~y and Green OM~ + HU.. Chemistry 125 , 11,,'A~ GRffNREAGENT ~ - ~.. , ~ th. nts are said to be gre en whn ent ~y ~e eas ily availabl:,_(preferably f.he rea~~ral ren ewa ble~- smirces ) imu m ato m eco nom y ,,._, on- mac , l$!Ve max J1l naL L-U ~~~ ~ non-toxic ana biode ada ble. :d ~ e pro duc t~ f~~ ed if an are conventi 7 me t Y atio n _rea ctio ns were car ried oy usm g Me thy l ver y toxic, hen ce the syn the sis is _,;des or Methy_ Sul pha te whi ch are - I ~ -:lf~ble b~aes Tun ao -- dev. elop, ed a m eth od to met hyl ate acti.ve -me thy ene.. : --:-- (DM Q wjt bou t pro du cin g any UJlrnpounds usm g p1m eth yl Car bon ate co · alts. ~~ ' H3CXCN ,':f CN 9 O 1, + H3 C'- o/t ,o, ,..c H3. K2C03 ·+ CH30H + CO2 ¥ R con >4-- ven -~ DMC ~ _. e _ f':" _ tion a me tho d, Sty ren~ (the Mo nom er · R use d for the ·. In the e qua ntit ies ~ve_ry yea r is ~8: de manufacture of pol~styre~e) use d in larg · Crafts alky lati on. from Benzene (carcmogeruc) by Friedal-. HCI/ AICI 3 - (YI CH2CH3 63oo c --~ v·7" CH =C H2 I 0 + ~ = ~Fried. a! c: afts ~ alky latio n ZnO or Cr2 03 ~ Styr ene. by Cha pm an, a sing le ste p In.the green· syn the sis whi ch is developed is used to con ver~t.pced /jm;:;_,;od ~~~e. (better ato m ec ; ; ; ; ~.GREENREACTIO~ ~~ / Li_°7\.!!) ~ { 4/r!> ~ 0' of Atom Eco nomy". The con cep t 'Green Reactions' is bag ed on the "C n~e pt the ear lier sec tion. Few·exa mp les ofAtom Economy is des crib ed in details in of Green Reaction are given below:.zl res iso flb up rof en """"'-- ~ ~ -~ ~ developed by Boo ts Co mp any The conventional syn the sis of Ibu pro fen was ces s wit h an ato m eco nom y of of England in 196 0. Thi s is a six step pro eloped by BHC com pan y is a thr ee 40.1 % where as the gre en Syn the sis dev step proces~ ~. ; ~n~ ~fp;:.1 ~. ✓Tllll Synthesis o/lt,uproJen. 0 II CH · - C i CH3 --, 0- AlCl3 ·~? ~ 'CH CICH2C02C2Hs 3 CH ~ CH3 -C- O-C - CH3 ~ NaOEt -r. II II CH3.w.,,...o· 3· vJ, ~ °'" ~ ~ v A t ; t.--..~ ' ~...,,_..~~ cMJIV./.. 0 & ;~..,.,,(~ ~ J:o ~ 6-v ~ ~ 61 ~ ~~.  - --- li--lllul 126 - Textbook of Envi~nmenial Studie;. CH o C C02C2Hs H30+ CH3 Ibuprofen Atom economy by this process is only 40.1 ~ Gr'1' Synthesis ~ om Economy by this proce~s is ZZ..4~/g_, ' ' 0 II HF I - -: : C........_CH3 Cw3 Q Raney Ni/H2 ➔ CH3-C-O-C-CH3 II II CH3 0 0 CH3 CH~ -~ ~ ·cooH CH3 Ibuprofen ~ ofMethyl Met,.,.;,,ylate Methyl methacrylate is used in large quantities for the manufacture of polymers. The conventional method uses HCN (highly poisonous) with an atbm economy of ·o nly ~ whereas the green ·synthesis developed by Shell corporation uses Pd catalyst with an atom economy of 100%. · Con~ onal Method ✓ 0. II HCN C CH3-C-COO CH3 CHi 'CH3 J II. CH2 - Acetone Atom economy is ~ · Methyl Methacrylate <  l Green T~ch~ !OQY a~d G;~e~ Ch~misiry. 7 127 \ ·- ' 0, -- ~s is ~sc- c- cH + co + CH,OH __ ~e Pd _ CH3 -c - II co o CH3 CH2 Methyl Met hacr y!dt e no.rnY by. this me tho d is I 00%. tJlgco AtO iS ofAd ipi c Ac id.. sgn theS.... the sis of ntit ies for the syn. aci d wh ich is req uir ed 1n larg e qua nic ). The from Ben zen e (ca rcin oge AdiplCers was con ven ti~n ally pre ~ar ed wh ich con trib ute s to gre enh ous e pol ~du ct for.med by this ~et hod 1s N2 0 b)'"P s well as res ult s in the des tru ctio n of Ozo ne lay er. The gre en effect ais of Adi pic aci d is env iron me nta lly ben i~ and is syn the siz ed fro m dev elo pei by j_w. Fro st and K.M. syn oth es se usi ng bio cat aly st. Thi s wa s. D atuc (Reaction 1s th. d esc n"be d 1n. det ails in the.sec tion of gre en. sta rtin g. · vra s · ma~ri~). _ _ _ _,.~ ET HO DO LO GIE S rna tive to the ·e xis ting me tho ds, ~~ ~o do iog ies are ·des ign ed as an alte ts, cat al~ sts , by pro duc ts or Ne~hat tox ic sta rt~ ng ma~e~ia~s, rea gen lly elim ina ted. Few me tho ds. \ ~o rmediates are eith er bm1n. 1mized h. or tota , f..f~~ , fv1. ~1 --r , _ · all : U V, ~ "'n , ,~ ~ 111te the env iron me nt Y en1gn syn t es1s are 1 ~-. ~ ~ J(j ~~ , ~ Q. 1 ~... ~o ca ta ly sts The use of bio c£i~y sts hav e the gnzymes are al~o kno wn as bio cat aly sts. following adv ant age s. nt tem per atu res and pre ssµ res. The rea ctio ns are per for me d at am bie in aqu eou ~ me diu m. Most of the rea ctio ns are car ried out ste p con ver sio ns. The con ver sio ns are nor ma lly 'sin gle · ·,, -· - -.. ~.... Atom eco nom y is · ma xim ize d. ··· ·· ·· Conversion are ster eos pec ific. ma jor cla sse s. The Bio cata lyst s are cla ssif ied into six Bio cata lyst s J ~ Oxidoreductases i Transferases l--ses Hyd rola ! ·Ly s ase Iso ! mera ses l Lig ase s I. 0% ido red uct ase s: Th ese enz ym e cat aly ze oxi dat ion red uct ion reaction. er of var iou s fun ctio nal 2 · 'l'ran.aferases: The y cat aly ze the tra nsf groups. 3 hyd rol ytic rea ctio ns. · H~ las es : The se enz ym es cat aly se  128. - Textbook of Environm~ntal Studies 4. :.yases: Car ry o~t the add itio n and elim inat ions of sma ll moleCUles 3 on sp hybridized carb on atom.. 5. Isomerases: Responsible for the isom eris atio n reac tion s. 6. Ligases: They cata lyse the formation or cleavage of sp3 hybridized carb on...fe ofAquecrus Me diu m as Solvents The adv anta ge of usin g wat er as a solvent st... m ead of org amc solvents. tha t, it is che aply available, safe (n?n-inflam mable), no~-carcinogenic ~~ sim ple in ope rati on. It has the h1gh~st valu e of specific hea t. The few reac tion carr ied out in aqu eou s ·me diu m are. 1. Diels Ald er reru:tion: Heterocyclic com pou nds with Nitrogen or Oxyg con tain ing dienophiles are syn thes ise · d usm · g th'is reac 2... Cla isen Rearrangement: The ther mal rea tion. en rr~ gem ent of Allyl vinyl eth er to give aldehyde it1 pur e wat er. 3. Mif_hae(RPnction~'>: ~-Methyl-cy?lopenta ne-1, 3-?ione whe n reacted wit h vinyl keto ne in wat er gave a 5- 6 fuse d nng syst em without usin g a bas ic. cata lyst (as in conventional method). 4. f\ld ol Conde.nsatiop: yiny l _ke~o nes can be obt ai~e d by the reaction of 2-a lky l-l, 3, diketones wit h aqu eou s form aldehyde usin g 6 _ io M aqu eou s-po tass ium carb ona te as bas e. Atte mpt s are also being mad e to carr y out the reac tion s in the solid stat e. Som e of the solid pha se reac tion s whi ch are alre ady carried out successfully are halogenation, hydrohalogenati on (addition ofHBr), Michael Addition, Dehydration of Alcohols to Alkenes , Aldol con den sati on, Grignar reac tion s and man y othe rs. r. 0 ~ CHEMICAL PRODUCTS · ¼ : :~e n pro duc ts are tho se ~hi ch serv e the sam e function without them selv es bei n[. toxic or brea king down into toxic sub s. For ex~ ple s man y insecticides use organochlorines, org ano pho sph ates , or carb ainat_es. Org ano chlo rine com pou nds (lik a]drin, diel dn nf-ai:e_r_eadily incorporated into the food cha µi,JY_h erea~ org_anophospha tes and carb ama tes although are less per sist ent in the environment (DDT). but they readily ~ecompose in the env iron men t and tend to be toxic to hum an bein gs and othe r non- targ et org anis m. A new clas~ of inse cticides (diacetyl hydrazine) developed by Ro h~ _a nd Has s is non-toxic. e/, (D ~ ¼ k - The conventional antifouling agent use d on ~ boa ts is Tributyltin · (TBT) co m~ ds. Anti[ouling age nts are use d on boa t nul ls to"'r edu ce the build- - - up mar ine org anis ms, suc h as algae, plan ts, diat oms etc). TBTcompounas are per sist ant in the envn:onment and resu lt in bioaccu mulation in v'arious mic ro~. ~ \, m and Has s developed DCOI {4, 5 dichloro-2-n 3-o ne) as anti iou ling age nt which is less. per -octyJ -4;-iso thiazolin- sist ent in 6iarioi: environment as ~el l as the pro du~ t o~ meta?olism are also nor:i:_~oxic. J  l 0 Cl;:; N-( CH 2hC H3 - Cl g/ Ho , C -- · (DOC!) NH ,.......-OH I 0 NH , / 0 I-I1 1C s/. C- 0 / C \ 0 - H1 1C s~ C OH I ~et abo lic rea ctio ns of DCOI 5,G~.l!AO'yij~Si~ :!E~HNqi.~cj~. :·· ·. mistry. In this con~- ~ ·.:;-!· : ,~:.. :~ n che cep t.- was te technology_ is the ess enc e o(g ree zer; dolo ·es are deVIsed for.the syn the sis in suc h· a ma nne r tha t the re · any wa s e ,y pro uct_s are n~ ~m du cts for me d dur ing a rea ctio ~, or sta rtin g ma teri als of oth er 1°-: l~· or ~th e1 -,._ can be use d as raw mat eria int o the fo.__..!fhus zer o wa ste is the rec ycl ing of all ·ma ter ials bac k ' k t 1 · nne- r tha t pro tec ts hu ma n healt h unit s. n a ~ e ma r e P ace r., a ma _.. _ ·. _. an~~nt.. : AJtN. exa mp les. This can be exp lrun ed by the followin~ :· ·. ~ The gla ss mil k bot tle whca.icliIn is con sum ers is ma de of sili use d for dis trib uti ng mil ~ to the the nor ma l wa ste me tho ds, the bot tles t. can be dis pos ed to a lan dfil l by the ' was te me tho d, the bot tle can be rec ycl mu nic ipa lit- J. Bu t in the z_e ro ed, red uce d to its con stit uen t any oth er gla ss pro du~ t.. l&. rfJ par t and fo~ ed into a new mil k bot tle or pro duc t fro m am mo nia. Car bon dio xid e wh ich is for me d~ a · by ts_is use d as a blo win g ag~_n t fo_r 1 - ma nuf act uri ng and nat ura l gas uni ma kin g ext rud ed pol yst yre ne foa m she and hyd rofl uor O car bon s wer e use d tjis et. ·Ea rlie r chl oro fluo ro car bon s... tea d of liqu i~ ~d sup erc riti cal d into the atm osp her e, the y car bon dio xid e. Wh en CF C's are rele ase. ' stra tos phe re; wh ere the y ·.are.,,,,,, , -. I I rise ·tho ugh the tro pos phe re into.the to che mic al dec om pos itio n of dec om pos ed by UV rad iati ons. The pho mic chl ori ne wh ich res ult s.in ·cFC 's res ults in the for ma tion of ato m the atm osp her e. wn ich is the dep leti 9n of the ozo ne lay ets fro c_a tar act am ong ma ny oth er resp ons ible for cau sin g ski,~ can cer and as a blo wir tg age nt in ma kin g dise ase s. The use ol sup erc ntic al CO2 nth esi s) ha s the fol low ing pol yst yre ne foa m she et (gr een Sy · adv ant age s. · ts, the by pro duc t for me d ~ 'Fro m the am mo nia m~ ufa ctu rin g unicon trib ute to gre en hou se. i.e. CO2 is rem ove d hen ce it doe s not · effe ct~ s ~ It rep lac es CF Cs (whimp ich res ult s in ozo ne dep leti on) thu act on the env iro nm ent. red uci ng the adv ers e e£QD.Wllical, eas y,!Q..h,_andle, ~ Ap art from oth er adv ant age s, CO2 is the ozo ne lay er. · and nei the r for ms sm og or dep lete s r '" tlUil iHSl 130. Textboo k of Environ mental Studies EXER CISES 1. What is Green Techno logy? tJl 2. What are the basic princip les of green Chemis try? 3. Which princip le of green chemis try refers to 'Atom Econom y'? " 4. Benzen e is oxidize d to maleic anhydr ide. Calcula te the 'Atom Econom y this reactio n. t or s. It is said "Preven tion is better than cure' Justify this statem ent in c to 'Green Chemis try'. ontext 6. What are the various tools of Green Chemis try? 7. Write Short notes on: (a) Zero waste Techno logy. (b) Green Reagen ts. (c) Atom Econom y. (d) Green Startin g Materi als. 8. Chemi sts someti mes refer to "by-pr oducts " rather than "waste " List one advant age and one disadv antage of using this term. · 9. Consid er the followi ng two reactio ns: H2C H Heat "'/ ~ + H 2o Tri methyl propyne amine ion CH2 Propene Reacti on 1 H3C H 1-propo nol Heat "'/ ~ + H 20 CH2 Propene Reacti on 2 Which of the two reactio ns have a better Atom Econo my? 10. What do you unders tand by the term 'sustai nabilit y'? 11. illustr ate with examp les 'Green Reacti ons'. 12. How do the green startin g materi als help to improv e the enviro nmenta l condit ions. ·· ,. 13. What is "Waste " produc t? How does the law of Conse rvation of Matter justify this word. · 14. How is the new synthe sis of Ibupro fen better than the conven tional synthe sis. 15. Why unnec essary deriuit ization in a reactio n should be avoide d?..oa□ I