ACYL COMPUNDS: SOAPS AND DETERGENTS

EXPERIMENT NO. 12 ACYL COMPUNDS: SOAPS AND DETERGENTS I.

INTRODUCTION

II .

RESULTS AND DISCUSSION

A. Solubili Solubility ty and Acid Acidity ity of Carbox Carboxylic ylic Acids Acids 1. Water Solubili Solubility ty (+ miscible) miscible) Sample

Observation

Reaction it! blue litmus paper #lue$ #asic Red$ Acidic

Acetic acid (+) clear" colorless #en%oic acid (&) clear" colorless Sodium (+) clea clearr" col colorl orless ess #lue$ lue$ #as #asic #en%oate Carboxylic acids are substances t!at !ave a 'eneral formula of RCO . *!ey are considered as #ronsted&ory acids or proton donors. *!ey are polar since t!ey can be bot! be !ydro'en&bond acceptor and donors due to t!e presence of t!e carbonyl and !ydroxyl 'roups respectively. *!ere are instances t!at t!e !ydroxyl and carbonyl 'roup !ave t!e tendency to self&associate and become less soluble if t!e carbon no increases. ,n t!e experiment" all t!e samples are soluble in ater except for ben%oic acid. Acetic acid" C -COO" and sodium ben%oate" aCO -" are very polar t!us t!ey are soluble in ater. #en%oic acid did not dissolve because it contains 'reater number of carbon atoms (C/0COO). Sodium #en%oate is t!e least soluble amon' t!em since it is sli'!tly alaline due to t!e formation of carbonic acid and !ydroxide ion. . Relative elative Aciditie Acidities s of Carboxylic Carboxylic Acids Acids and 2!enols 2!enols Sample #en%oic Acid 2!enol

Reaction it! 134 aO !etero'eneous

Reaction it! 13 4 aCOappearance of  bubbles

 layers are visible  5elly lie li6uid forms  5elly lie li6uid forms at at t!e bottom t!e bottom

#. ydrolys ydrolysis is of Acyl Acyl Compou Compounds nds Sample

Si'n of reaction

 *est  *est it! #lue itmus 2aper

eat evolved$ Acetyl C!loride bubbles formed Red$ Acidic (un!eated) o reaction Acetic Any!ydride Red$ Acidic (!eated) o reaction #en%amide #lue$ #asic (!eated) ydrolysis is t!e reaction of or'anic compound it! ater !erein a bond in an or'anic molecule is broen as ell it! t!e O& bond of ater molecule. Since acyl 'roup is derived from carboxylic acid" t!ey ill become carboxylic acids !en t!ey under'o !ydrolysis. Acetyl c!loride (C -COCl) is an acyl c!loride t!at reacts vi'orously it! ater becomin' rapidly !ydroly%ed. !ydroly%ed. Steamy !ite fumes of !ydro'en c!loride can be seen. *!at is !y in t!e experiment" !eat evolved from t!e test tube. Acetic any!ydride ((C -CO)O) is t!e simplest isolatable of acid an!ydride. W!en it dissolves in ater" it !as a limited stabi stabilit lity y becaus because e it !ydro !ydrolys lyses es to 'ive 'ive acetic acetic acid. acid. *!er *!ere7s e7s no si' si'n n of react reaction ion in t!e experiment but t!ere as a reaction !ic! probably cannot be obviously seen. #en%amide

(C/0CO) is a derivative of ben%oic !ic! is less soluble in ater t!an t!e previous samples due to !i'!er number of carbon atoms compared to acetic c!loride and acetic an!ydride. Since it contains an amide" it is basic. C. Saponi8cation of Coconut Oil Saponi8cation is t!e base&promoted !ydrolysis of fats and oils producin' 'lycerol and a mixture of fatty acid salts called soaps. ,n t!e preparation of soaps" coconut oil !ic! !as tri'lycerides are !eated near to boilin' it! aO. At molecular level" saponi8cation corresponds to t!e base & promoted !ydrolysis of t!e ester 'roups in tri'ylcerides. After t!e !ydrolysis is complete" sodium c!loride is added to precipitate sodium salts as t!ic curds of soap. 9. Comparison of Soaps and 9eter'ents 1. ydrolysis Sample

*est it! red litmus  *est it! blue litmus paper paper 9eter'ent Red to blue #lue to blue Soap Red to blue #lue to blue Soap is dissolved in arm ater because of its insolubility in ater and 'ives a colloidal mixture !ile synt!etic deter'ents are mostly AS or liner alyl&ben%ene& sulfonates$ bot! are basic !en tested on litmus paper. . Reaction it! Acid Sample Observation 9eter'ent #ubbles risin'" colorless layer (clear) Soap Cloudy mixture$ !ite precipitate Soaps are also less e:ective in acidic ater compared to deter'ents (synt!etic deter'ents soluble in bot! acidic and alaline solutions). *!e lon' !ydrocarbon c!ains of  natural soaps are insoluble in ater" t!ey tend to cluster in suc! a ay to minimi%e contact it! ater and t!us form ater&insoluble salts especially !en ions suc! as calcium" ma'nesium" and iron are present in ater. -. Reaction it! ;Soft< and ;ard< Water Sample 9eter'ent

aCl Clear solution

CaCl Cloudy solution Clear solution$ !ite Soap Cloudy solution precipitate 9ue to t!e presence of Ca(,,) ions in ater" for soap" t!ere is less tendency for soaps to produce bubbles and t!e nonpolar !ydrocarbon inner parts of soap micelles !as less tendency to dissolve nonpolar dirt molecules. 9eter'ents are not 'reatly a:ected by !ard ater or presence of Ca(,,)ions and ot!er mineral ions present in ater since t!ey are synt!etically made it! 1&3 carbon atoms lon' and a polar 'roup at one end of t!e molecule t!at does not form insoluble salts. =. >mulsifyin' Action Sample 9eter'ent Soap Water #lan

Observation >mulsi8ed$ less cloudy$ more frot!  *urbid layer$ less emulsions$ less frot!  *o separate layers$ did not emulsify

,n t!e experiment" deter'ent !as emulsi8cation" !ile soap" !as turbid layer !ile t!e ater !as not!in' at all. *!is means t!at deter'ents are not 'reatly a:ected by !ard ater or presence of Ca(,,)ions and ot!er mineral ions and can still convert t!e soluble sodium carboxylates are converted into insoluble metal salts. W!ile soap !as turbid layer !ic! means it emulsi8ed less" and ater as least amon' t!em all to emulsify. III. IV.

CONCLUSION REFERENCES/BIBLIOGRAPHY 

C!em --.1 aboratory ?anual C!em --.1 Course Syllabus @oens. (33/). Solubility of Or'anic Compounds. ort! Seattle BacWeb V.

ANSWERS TO QUESTIONS

1. >xplain t!e di:erence in t!e solubility of ben%oic acid and sodium ben%oate in ater. W!ic! of t!e to ould you predict to be more soluble in CCl - >xplain.  *!e di:erence in t!e solubility of ben%oic acid and sodium ben%oate in ater is t!eir polarity. #en%oic acid is non&polar !ile sodium ben%oate is polar. Wit! t!is" only sodium ben%oate is soluble in polar ater. *!eir di:erence is due to t!eir molecular structure. #en%oic acid is an aromatic carboxylic acid !ile sodium ben%oate is a combination of alali metal it! carboxylic acids. CCl - is polar so sodium ben%oate is predicted to be soluble on it. . #ased on t!e results in 2art A." !at can be said about t!e relative acidities of p!enols and carboxylic acids Arran'e t!e folloin' compound types in order of increasin' acidity carboxylic acid" alco!ol" p!enol and ater. ,n order of increasin' acidity ater D alco!ol D p!enol D carboxylic acid -. #ased on t!e results in 2art #" arran'e t!e folloin' compound types in t!e order of  decreasin' !ydrolysis rate acid !alides" acid an!ydrides" esters" and amides. Eive t!e t!eoretical explanations for t!e observed di:erences in reaction rates.  *!e order of decreasin' !ydrolysis rate is acid !alides F acid an!ydrides F esters F amides. *!is is based on t!eir acidities !ere acid&!alide as t!e more acidic so it can !ydroly%e more" and due to t!e presence of amine in amides" it7s t!e most basic and can7t readily !ydroly%e. =. ,s t!e soap ater mixture a true solution Cite examples to support your anser.  *!e soap ater mixture is considered to be colloidal t!at7s !y it is not a solution. *!e soap solute present in ater is not !omo'enous or totally dissolved in ater. *!is can be seen if li'!t is passes directly to t!e mixture" and t!e scatterin' of  li'!t ould t!en be observed. *!e composition and p!ysical properties vary from one part of t!e mixture to anot!er. ,f t!e soap ater mixture is subGected to a beam of li'!t" a *yndall e:ect ill tae place. *!e evident scatterin' of li'!t is not a c!aracteristic of a true solution" but rat!er a 6uality of colloidal dispersion. 0. W!at is a colloidal mixture o does a colloidal mixture arise !en soap is mixed it! ater A colloidal mixture is a mixture !erein particles !ic! t!e mixture contains is lar'er t!an normal solute but smaller enou'! to remain suspended in t!e dispersin' medium. Colloidal mixture arises !en soap is mixed it! ater because t!e particles tend to attac! more it! eac! ot!er t!an in ell dispersed in ater. /. On t!e basis of t!e litmus test" are t!e soap&ater and deter'ent&ater mixtures acidic" basic or neutral >xplain t!e di:erence" if any in t!e reactions of t!e soap&ater and deter'ent&ater mixtures to litmus paper.

,n t!e experiment" bot! soap&ater and deter'ent&ater mixtures are basic. H. W!ic! ould you predict to !ave a 'reater emulsifyin' poer in ;!ard ater