REAKSI PADA ALKOHOL, ETER, ALDEHID, KETON, ASAM ...

R E A K SI PA D A A L K O H O L , E T E R , A L D E H I D , K E T O N , A SA M K A R B O K SI L AT, D A N E S T E R G i l a n g R a d h it ya P r a t a m a , 1 2 5 1 0 0 6 0 1111 0 1 ( K) K et e k n i k a n P er t a n i a n , F a k u l t a s Te k n o l o g i P er t a n i a n , U n i v er s i t a s B r a w i j a y a

Alkohol A l k o ho l a d a l a h s e n ya w a - s e n ya w a d i m a n a s a t u a t a u l e b i h a t o m h i d r o g e n d a l a m s e bu a h a l k a n a d i g a nt i k a n o l e h s e bu a h g u g u s – O H ya n g m e m i l i k i r u m u s k i m i a C n H 2 n + 1 O H . A l k o ho l d i b a g i m e n j a d i be b e r a p a k e lo m p o k , t e r g a nt u ng ba g a i m a n a p o s i s i g u g u s – O H p a d a r a nt a i a t o m- a t o m k a r bo n n ya . ( S u t r e s n a , 2 0 0 7 ) a . A l k o ho l P r i m e r A l k o ho l p r i m e r m e r u p a k a n a l k o ho l ya ng g u g u s – O H t e r i k a p a d a a t o m C p r i m e r ( a t o m C ya ng t e r i k a t p a d a s a t u a t o m C ya ng l a i n n ya ) C o nt o h: e t a no l CH3 – CH2 – OH b. A l k o ho l S e k u n d e r A l k o ho l s e k u nd e r m e r u p a k a n a l k o ho l ya ng t e r i k a t p a d a a t o m C s e k u nd e r ( a t o m C ya n g t e r i k a t p a d a 2 a t o m C l a i n n ya ) C o nt o h: 2 - B u t a no l CH3 – CH – CH2 – CH3 OH

c . A l k o ho l Te r s i e r A l k o ho l Te r s i e r m e r u p a k a n a t o m k a r bo n ya n g m e n g i k a t g u g u s – O H b e r i k a t a n l a n g s u ng d e ng a nt i g a g u g u s a l k i l , ya n g b i s a m e r u p a k a n k o m b i n a s i d a r i a l k i l ya n g s a m a a t a u b e r b e d a . C o nt o h: 2 - m e t i l, 2 - p r o p a no l CH3 CH3 – C – CH3 OH

Reaksi Pada Alkohol R e a k s i – r e a k s i p a d a a l k o ho l d i g u n a k a n s e b a g a i p e n g e n a l a l k o ho l a t a u u nt u k m e n g i d e nt i f i k a s i j e n i s – j e n i s a l k o ho l. a. Rea ksi identi fi kasi a lkoho l d engan mengguna kan loga m n a t ri u m R e a k s i i n i m e r u p a k a n r e a k s i ya n g p a l i n g u m u m d a n m u d a h d i l a k u k a n, s e r t a d i a m a t i. R e a k s i i n i d i g u na k a n u nt u k m e m b e d a k a n a l k o ho l d e ng a n e t e r, k a r e na e t e r t id a k b e r e a k s i d e n g a n lo g a m n a t r iu m . A l k o ho l be r e a k s i d e n g a n na t r iu m d a n m e ng h a s i l k a n g a s h i d r o g e n d e n g a n p e r s a m a a n be r i k u t 2R – OH + 2Na

2R – ONa + H2 (g)

C o nt o h:

b . R e a k s i i d e n t i f i k a s i a l k o h o l m e n g g u n a k a n f o s f o r t ri h a l i d a R e a k s i a l k o ho l d e n g a n fo s fo r t r i h a l i d a i n i m e n g h a s i l k a n a l k i l ha lid a de nga n p ersa ma a n se baga i ber ik ut .

C o nt o h :

alkohol l

c. R e a k s i o k s i d a s i u n t u k m e m e b e d a k a n j e n i s a l k o h o l

U nt u k me m b e d a k a n j e n i s a l k o ho l p r i m e r, s e k u n d e r, d a n t e r s i e r d i g u na k a n r e a k s i o k s i d a s i . P e ng o k s i d a s i a n ya n g d i g u na k a n b e r u p a K M nO 4 u nt u k r e a k s i d a l a m s u a s a na ba s a d a n K 2 C r 2 O 7 u nt u k reak si da la m sua sa na a sa m. a. O k s i d a s i a l k o ho l p r i m e r R e a k s i o k s i d a s i a l k o ho l p r o m e r m e n g h a s i l k a n s e n ya w a a l d e h i d . J i k a a l d e h i d d io k s i d a s i k a n l e b i h l a n j u t ma k a a k a n d i h a s i l k a n a s a m k a r bo k s i l a t , d e n g a n p e r s a m a n s e b a g a i b e r i k u t ;

Z a t a nt a r a ya n g t e r be nt u k t id a k s t a b i l . O l e h k e r e na it u s a l a h s a t u g u g u s – O H a k a n d i b e r i k a n k e a t o m H d a r i g u g u s – O H ya n g l a i n d a n m e m b e nt u k m o l e k u l H 2 . K e m u d i a n , a t o m C d a n a t o m O m e m b e nt u k i k a t a n r a ng k a p d u a .

S e t e l a h s e n ya w a a l d e h i d t e r b e nt u k , s e n ya w a a l d e h i d d a p a t d io k s i d a s i l e b i h l a n j u t m e n j a d i a s a m k a r bo k s i l a t .

b. O k s i d a s i a l k o ho l s e k u nd e r R e a k s i o k s i d a s i a l k o ho l s e k u n d e r m e n g h a s i l k a n k e t o n m e l a l u i m e k a n i s m e be r i k u t :

c . O k s i d a s i a l k o ho l t e r s i e r P a d a a l k o ho l t e r s i e r t i d a k t e r j a d i o k s i d a s i k a r e n a a t o m C ya n g m e n g i k a t g u g u s – O H p a d a a l k o ho l t e r s e bu t t id a k m e ng i k a t a t o m H . B e r be d a d e ng a n a l k o ho l p r i m e r d a n s e k u n d e r ya n g m e n g i k a t a t o m H . U nt u k m e n n g i d e nt i f i k a s i a k o ho l t e r s i e r ya it u d e n g a n m e n g g u na k a n c a r a u j i L u c a s Ya it u d i r e a k s i k a n d e n g a n Z n C l 2 d a l a m H C l p e k a t . U j i l u c a s i n i b e r d a s a r k a n r e a k s i a nt a r a a l c o ho l d a n k a t a l i s Z n C l 2 . A l k o ho l t e r s ie r b e r e a k s i c e p a t d e n g a n g e j a l a r e a k s i b e r u p a t e r be nt u k n ya k a b u t d ip e r m u k a a n l a r u t a n. A l k o ho l s e k u nd e r b e r e a k s i d a l a m w a k t u s e k i t a r 5 me n it , s e d a ng k a n a l c o ho l p r i m e r t i d a k m e n u n n j u k k a n t e r j a d i n ya r e a k s i .

Eter E t e r a d a la h s u a t u s e n ya w a o r g a n i c ya n g m e ng a nd u ng u n s u r R - O - R ` , d e ng a n R s e b g a i a l k i l . G u g u s e t e r i n i j u g a s n g a t u m u m d i g u n a k a n s e b a g a i p e ng h u bu n g p a d a s e n ya w a k a r bo h i d r a t d a n l i g n i n . ( s u ya t no , 2 0 0 6 ) R e a k s i ya ng t e r j a d i p a d a e t e r a. Rea ks i o ks ida si C o nt o h ; CH3 – O – CH3 + 3O2

2 CO2 + 3H2O

E t e r mu d a h t e r ba k a r d a n m e m b e nt u k g a s k a r bo n d i o k s i d a d a n u a p a ir

b. R e a k s i d e ng a n P C l 5 C o nt o h ; R – O – R` + PCl5

R – Cl + R` - Cl + POCl3

c. Rea ks i h idro lis is et er B i l a e t e r d i d i d i h k n d a l a m a i r ya n g m e ng a nd u ng a s a m 9 u m u n ya H 2 S O 4 ) m a k a a k a n t e r j a d i h i d r o l i s i s y a ng m e n h a s i l k a n a l c o ho l C o nt o h C2H5 – O – C2H5 + Cl2

CH3CHcl – O – C2H5 + HCl

Aldehid A l d e h i d a m e r u p a k a n s e n ya w o r g a n i c ya n g m e m i l i k i g u g u s k a r bo n i l t e r m i n a l. G u g u s f u ng s i i n i t e r d i r i d a r i a t o m k a r bo n ya n g b e r i k a t a n d e n g a n a t o m h yd r o g e n d a n b e r i k a t a n r a n g k a p d e ng a n a t o m o k s i g e n. G o lo n g a n a l d e h i d j u g a d i n a m a k a n g o lo ng a n fo r m i l a t a u m e t a no i l . Ka t a a l d e h i d a m e r u p a k a n k e p e n d e k a n d a r i a l c o ho l d e h i d r o g e na s i ya n g be r a r t i a l c o ho l ya n g t e r h i d r o g e n a s i . G o lo ng a n a l d e h i d be r s i f a t p o la r ( s u h e nd a r, 2 0 1 0 )

Rea ksi pada a ld ehid a . R e a k s i i d e nt i f i k a s i U nt u k me n g e n a l a d a n ya g u g u s a l d e h i d d a n k e t o n d a l a m s u a t u s e n ya w a m a k a d i l a k u k a n d e ng a n p e r e a k s i 2 , 4 – d i n i t ro f e n i l h i d r a z i n d a n m e m b e nt u k s u a t u e nd a p a n. P e r s a m a n r e a k s i n ya a d a l a h s e b a g a i ber ikut :

b. R e a k s i d e ng a n H 2 R e a k s i a l d e h i d d e ng a n H 2 a k a n m e n g ha s i l k a n a l k o ho l p r i m e r C o nt o h ;

c . R e a k s i a l d e h i d d e ng a n H C N

d . R e a k s i a l d e h i d d e ng a n N a H S O 3 A d i s i N a H S O 3 p a d a a l d e h i d a k a n m e n g h a s i l k a n z a t ya n g s u k a r l a r u t . R e a k s i i n i d a p a t d i g u n a k a n u nt u k m e m i s a hk a n a l d e h i d a s u a t u ca mp ura n . P ersa ma a n re ak si d ar i re ak si in i a da la h se bag a i ber ikut ;

e. Oksid a si de nga n a ld e hid a A l d e h i d a d a p a t d io k s i d a s i m e n g g u na k a n o k s i d a t o r ya ng l e m a h . P e r e a k s i To l l e n s d a n F e h l i n g a d a l a h o k s i d a t o r l e m a h ya n g m e r u p a k a n p e r e a k s i k hu s u s n u nt u k m e ng e n a l i a l d e h i d a . Perea ksi Fe hling

R e a k s i a nt a r a a l d e h i d d e ng a n f e h l i n g a k a n m e n g ha s i l k a n e n d a p a n m e r e a h j i k a b e na r t e r d a p a t a l d e h i d P e r e a k s i To l l e n s

Rea ks i a ld e hid de nga n t o lle ns me ngk ila p sep ert i c er min per ak

akan

me ng hasilk a n

e nd a p a n

Keton K e t o n a t a u b i s a d i s e b u t d e n g a n a l k a no n m e m i l i k i d u a g u g u s a l k i l ya n g t e r ik a t p a d a g u g u s k a r bo n i l , d a n p a d a a l d e h i d m e m i l i k i s e k u r a n g k u r a ng n ya s a t u a t o m h i d r o g e n ya n g t e r ik a t p a d a a t o m k a r bo n i l n ya . A l d e h i d d a n k e t o n m e m p u n ya i r u m u s mo l e k u l ya n g s a m a , ya it u C n H 2 n . ( S a l i r a w a t i, 2 0 0 6 ) Rea ksi pada K eton (A lkan on) a. Rea ks i ad is i ket o n de nga n H2 A d i s i h i d r o g e n p a d a a l k a no n a k a n m e n g h a s i l k a n a k o ho l s e k u nd e r.

Pada rea ksi ad isi in i t er jad i pe mut u sa n pada ik at an ra ngka p d i gug us a s e t o n d a n a t o m H a k a n t e r ik a t p a d a a t o m O d a n a t o m C .

b. R e a k s i a d i s i k e t o n d e n g a n H C N P e r s a m a a n r e a k s i a d i s i a s a m s i a n i d a p a d a a l k a no n.

c . R e a k s i a d i s i a l k a no n d e n g a n N a H S O 3 P e r s a m a a n r e a k s i a d i s i a l k a no n d a n N a H S O 3 .

A s a m K a rb o k s i l a t A s a m k a r bo k s i l a t a d a l a h s e n ya w a k a r b o n ya ng ba n ya k t e r d a p a t p a d a a l a m , m i s a l n ya a s a m a s e t a t , p a d a a s a m c u k a , a s a m f o r m i a t p a d a s e m u t , a s a m m a l a t p a d a a p e l, d a n a s a m s it r a t p a d a j e r u k . A s a m k a r bo k s i l a t m e m i l i k i r u m u s u m u m mo l e k u l C n H 2 n O 2 . As a m k a r bo k s i l a t ju g a s e r i n g d i s e bu t d e ng a n a s a m a l k a no a t . ( S a l i r a w a t i, 2 0 0 6 ) Rea ksi pada a sa m ka rbo ksi lat a . R e a k s i d e n g a n b a s a m e m b e nt u k g a r a m . At o m H d a r i g u g u s k a r bo k s i l d e ng a n m u d a h d i g a nt i d e ng a n a t o m lo g a m C o nt o h ;

b. R e a k s i e s t e r i f i k a s i ( p e m b u a t a n e s t e r ) P a d a r e a k s i i n i a t o m H d a r i g u g u s - C O O H d i g a nt i d e ng a n g u g u s a l k i l

ya n g b e r a s a l d a r i a l k o ho l

Est er E s t e r a d a l a h s e n ya w a ya n g d a p a t d i a ng g a p t u r u na n d a r i a s a m k a r bo k s i l a t d e ng a n m e n g g a nt i io n h i d r o g e n d e ng a n g u g u s h i d r o k s i l o l e h r a d i k a l h i d r o k a r bo n. R u m u s u m u m d a r i e s t e r a d a l a h

Reaksi pada ester a. H idro lis is e st er H i d r o l i s i s e s t e r b i s a d i s e bu t p e n ya b u n a n e s t e r, ya it u m e n g u b a h e s t e r m e n j a d i a l k o ho l d a n g a r a m ya n g be r a s a l d a r i t u r u na n n ya . N a m u n h i d r o l i s i s e s t e r a k a n s e m p u r n a j i k a d i d i h k a n d e ng a n a s a m basa sepert i NaOH. Ber ik ut reaksi hid ro lis is e st er;

b. Tr a ns e s t e r i f i k a s i Tr a ns e s t e r i f i k a s i a d a l a h p r o s e s k i m i a w i ya n g m e m p e r t u k a r k a n g r u p a l k o k s i p a d a s e n ya w a e s t e r d e ng a n a l k o ho l. Tr a n e s t e r i f i k a s i b i a s a n ya d i s e b u t d e ng a n a l k o ho l i s ya n g m e r u p a k a n t a ha p k o n v e r s i d a r i t r i g l i s e r i d a m e n j a d i a l k i l e s t e r. ( H a m b a l i , 2 0 0 6 ) C o nt o h ;

Daft a r Pust a ka

H a m b a l i , E r l i z a . 2 0 0 6 . J a r a k P a g a r. D e p o k : P e n e ba r S w a d a ya S a l i r a w a t i, D a s . 2 0 0 6 . B e l a j a r K i m i a S e c a r a M e na r i k . B a nd u ng : G r a f i n d o S u he nd a r, C u c u . 2 0 1 0 . K i m i a . B a nd u ng ; : k a i f a S u t r e s na , N a na . 2 0 0 6 . KI M I A. B a n d u ng : G r a f i n d o S u ya t no . 2 0 0 6 . KI M I A. B a n d u n g : g r a f i nd o