- WELCOME TO PART FOUR OF THE VIDEO TUTORIAL SERIES
ON ORGANIC FUNCTIONAL GROUP REACTIONS.
THIS PART OF THE SERIES WILL FOCUS ON HYDRATION
AND DEHYDRATION REACTIONS.
THESE REACTIONS ARE ASSOCIATED WITH REACTIONS
AT THE DOUBLE BOND,
PRIMARILY, CARBON-CARBON DOUBLE BONDS.
LET'S GET STARTED. ALL RIGHTY.
SO AS THE NAME WOULD APPLY,
IF IT'S A HYDRATION REACTION WE'RE GOING TO ADD WATER.
IF IT'S DEHYDRATION, WE'RE GOING TO REMOVE, RIGHT?
SO THIS IS ALL ABOUT ADDING OR REMOVING WATER,
BUT IT'S FROM DOUBLE BONDS.
BECAUSE LATER IN THIS SERIES,
WE WILL LOOK AT OTHER REACTIONS THAT INVOLVED WATER
BUT THEY WILL BE HYDROLYSIS.
SO IT'LL BE-- WE WANT TO MAKE SURE THAT HYDROLYSIS
AND HYDRATION AND DEHYDRATION,
WE WANT TO DISCERN THOSE AND RECOGNIZE
THE DIFFERENCE BETWEEN THEM.
SO FOR WATER, IT'S GOING TO BE REALLY HELPFUL
TO THINK OF WATER IN TERMS OF OUR UNDERSTANDING
OF ACID/BASE CHEMISTRY AND THE BONDING.
SO WE'LL THINK OF WATER
AS AN HYDROXYL GROUP AND A HYDROGEN.
AND SO FOR THE DOUBLE BONDS,
MOST OF THE REACTIONS WE'RE GOING TO LOOK AT WILL
BE REACTIONS AT THE CARBON-CARBON DOUBLE BOND.
WHEN WE GET TO OUR BIOCHEMICAL PATHWAYS LATER IN THE COURSE,
WE WILL SEE ONE EXAMPLE
WHERE THE WATER ADDS ACROSS THE CARBONYL GROUP.
SO WE WILL FOCUS HERE BUT BE AWARE
THAT THERE'S ONE IN THE FUTURE WHERE WE WILL SEE THAT.
ALL RIGHT.
SO HYDRATION OF ALKENES PRODUCES ALCOHOLS.
SO LET'S TAKE FOR EXAMPLE CYCLOPENTENE,
RIGHT, FIVE-MEMBERED RING WITH ONE DOUBLE BOND.
NOW, WE WILL ADD WATER ACROSS.
SO WE'LL THINK OF WATER AS HO-H.
SO THE HYDROCARBON SKELETON, RIGHT, IS THE--
IS GOING TO STAY THE SAME,
WE'RE NOT GOING TO BE MAKING OR BREAKING ANY CARBON BONDS.
WE'RE SIMPLY GOING TO ADD WATER ACROSS THIS DOUBLE BOND.
SO THERE ARE TWO CARBON ATOMS SHARING THE DOUBLE BOND,
ONE OF THOSE CARBON ATOMS GETS THE OH
AND THE OTHER CARBON ATOM GETS THE H. SO THIS IS THE HYDRATION
OF CYCLOPENTENE TO PRODUCE CYCLOPENTANOL.
AND THEN REMEMBER THAT TYPICALLY,
WE WON'T SEE ALL OF THIS DETAIL.
SO WHEN WE LOOK AT THE PRODUCT, IT COULD BE WRITTEN AS THIS,
SO THE HYDROGENS ARE FREQUENTLY NOT SHOWN.
HOWEVER, IT CAN BE HELPFUL TO WRITE IN THE HYDROGENS
TO HELP US RECOGNIZE THE CHANGE, RIGHT.
SO EVEN THE CYCLOPENTENE COULD SIMPLY BE WRITTEN LIKE THIS.
SO IT CAN BE VERY HELPFUL TO WRITE IN THE HYDROGENS
AND THE REGION OF THE MOLECULE WHERE WE SEE THE CHANGE
TO HELP US DISCERN WHAT TYPE OF REACTION IS OCCURRING.
AND SO BASICALLY,
THIS IS REVERSIBLE DEPENDING ON THE ENVIRONMENT AND THE ENZYMES.
NOTICE THE DEHYDRATION IS OF AN ALCOHOL TO PRODUCE AN ALKENE.
SO WE'LL JUST DO THE SAME REACT--
WE'LL JUST SWITCH EVERYTHING.
ALL RIGHT.
SO WE START WITH AN ALCOHOL AND NOW--
SO FOR DEHYDRATION,
RIGHT, FOR THE D, WE'LL SEE MINUS, RIGHT?
SO WE'RE GOING TO HAVE--
WE'RE JUST GOING TO HAVE TO DO H2O, RIGHT.
SO THIS IS MINUS IS FOR THE LOSS OF THE WATER, RIGHT?
SO WE'RE GOING TO LOSE WATER.
WE CAN SEE IT RIGHT THERE, RIGHT?
SO-- AND WHEN WE LOSE THE WATER WHAT HAPPENS, RIGHT,
WE FORM THAT DOUBLE BOND.
AND IN THE PROCESS, RIGHT, WATER IS RELEASED.
THERE'S THE-- THIS IS THE LOST WATER, RIGHT.
THE WATER IS LOST RIGHT THERE.
AND THEN, OF COURSE, WE WANT TO BE AWARE
THAT DEPENDING ON WHO'S WRITING THE REACTION,
THEY MAY NOT SHOW US THE HYDROGENS
BECAUSE THEY'LL EXPECT US TO SEE THEM THERE.
SO FOR OUR CLASS, I WILL JUST BE GIVING YOU SYMMETRICAL ALKENES,
SO THAT WE DON'T HAVE TO WORRY ABOUT SOME OTHER CONSIDERATIONS
THAT-- AND THE ADVANCED ORGANIC SYNTHESIS CLASS MIGHT CONSIDER.
SO HERE WE'LL START WITH A SIMPLE ALKENE, RIGHT.
WHAT'S THE NAME OF THIS?
TRANS, RIGHT, ONE, TWO, THREE, FOUR, FIVE,
SIX, RIGHT, TRANS-3-HEXENE.
SO THE FORWARD--
WE'RE GOING TO FOCUS ON THE FORWARD REACTION.
SO, IF WE'RE DOING THE HYDRATION REACTION,
WE'RE GOING TO ADD WATER ACROSS THE DOUBLE BOND.
SO, WE'RE FOCUSING ON CARBONS THREE AND FOUR.
THE CARBON SKELETON WILL REMAIN THE SAME.
THERE'S THE SIX, OKAY.
AND THEN HERE IS OUR--
SO, OUR CARBON CHAIN HASN'T CHANGED,
IT'S STILL SIX CARBONS.
AND NOW, WE WANT TO ADD THE WATER
ACROSS THE DOUBLE BOND AND SO,
WE'LL PUT THE OH HERE ON CARBON THREE
AND THE HYDROGEN ON CARBON FOUR,
RIGHT, RECOGNIZING
THAT WHEN WE SEE THIS WRITTEN IN A TEXT BOOK OR SOMETHING,
THEY MAY NOT SHOW THIS HYDROGEN
IF THEY'RE USING BOND-LINE STRUCTURES.
BUT EITHER WAY, IT'S THE--
THESE ARE THE SAME COMPOUND.
THEY ARE BOTH 3-HEXANOL, OKAY.
SO, THE OR THIS IS JUST SHOWING DIFFERENT WAYS
IT COULD BE REPRESENTED, RIGHT,
REALLY EQUALS. OKAY.
AND NOW, WE HAVE AN EXAMPLE SIMILAR TO UP ABOVE.
HERE WE HAVE OUR CARBON-CARBON DOUBLE BOND.
AND SO, WE HAVE CYCLOHEXENE, RIGHT, THINKING ABOUT WATER
AS HOH AND THE CARBON SKELETON REMAINS THE SAME
AND WE FOCUS OUR ATTENTION ON THE TWO CARBONS
THAT SHARE THE DOUBLE BOND.
ONE OF THOSE CARBONS GETS THE HYDROXYL LOOP
AND ONE OF THOSE CARBONS GETS THE HYDROGEN
AND DEPENDING ON WHO'S WRITING THE WORK,
YOU-- THEY MAY OR MAY NOT SHOW THAT HYDROGEN,
BUT YOU HAVE THE AWARENESS TO PUT IT IN, RIGHT?
THERE ARE OTHER HYDROGENS PRESENT HERE, RIGHT.
WE COULD-- THERE'S THOSE HS, I'LL JUST LEAVE THOSE IN BLACK
BECAUSE THEY ARE NOT PART OF THE REACTIVITY, OKAY.
NOW, WHEN WE GET TO THE METABOLISM OF FAT
IN STEP TWO OF THE BREAKDOWN OF FATTY ACIDS,
SO THIS IS-- THIS COMPOUND HERE WOULD BE DESCRIBED
AS AN OXIDIZED FATTY ACETYL-COA OR ACYL-COA
AND ALL OF THOSE TERMS WE'RE GOING TO LEARN IN THE FUTURE.
YOU'RE NOT RESPONSIBLE FOR THEM NOW,
BUT I JUST WANT TO GIVE YOU SOME CONTEXT
OF WHERE WE'RE GOING WITH THESE REACTIONS.
AND SO, HERE, WE CAN SEE THE WATER COMING IN HOH
AND HERE IS OUR DOUBLE BOND, ALL RIGHT.
SO, WE KNOW THAT THE CARBON SKELETON WILL NOT CHANGE.
SO, WE'LL JUST GO AHEAD AND DRAW THAT.
I THINK I'VE DONE THE CARBONS CORRECTLY.
OKAY. SO, THE CHANGE IS GOING TO OCCUR HERE.
AND SO, IN THIS EXAMPLE WHEN WE--
WHEN WE GET TO STUDYING TRIGLYCERIDES FATS,
HERE IS OUR CARBONYL CARBON.
SO, WE WOULD DESCRIBE THIS AS THE ALPHA CARBON
AND THIS AS THE BETA CARBON.
JUST FOLLOWING THE GREEK--
THE GREEK ALPHABET, ALPHA, BETA, GAMMA,
DELTA ,OKAY.
SO, WHEN WE GET TO THIS REACTION IN THE FUTURE,
IT'S NOT SYMMETRICAL ANYMORE LIKE OUR PREVIOUS EXAMPLES.
AND SO, WHAT WE'RE GOING TO LEARN IS THAT THE HYDROXYL GROUP
ALWAYS WANTS TO GO ON THE BETA CARBON
AND THE HYDROGEN GOES ON THE ALPHA CARBON.
SO, THAT'S NOT A DETAIL YOU'RE RESPONSIBLE FOR NOW,
BUT JUST TO HELP YOU MAKE THE CONNECTIONS
BETWEEN WHAT WE'RE DOING NOW AND THE BIOCHEMISTRY
WE'LL BE LEARNING IN THE FUTURE.
ALL RIGHTY.
SO THAT INCLUDES THIS TUTORIAL
ON HYDRATION AND DEHYDRATION REACTIONS.
PLEASE TAKE THE TIME NOW TO WORK WITH SOME REACTIONS
TO REINFORCE YOUR UNDERSTANDING.