Reaction Composition

Notices

1) Essential Due Date ranges: Experiment #6: Diels-Alder November. 1/2

Diene NMR in website Merchandise NMR in server (note: Exp. # follows HawkID) Experiment #7: Wittig 2) 3) Next Week: Experiment #8: Grignard Do it again Wittig lecture Nov. your five Nov. 8/9

Experiment #8: Grignard Response

- Grignard reaction: carbonyl compound and Grignard reagent - beneficial reaction in organic activity: forms C-C bond

Ur

X

3rd there’s r

MgX

Grignard reagent

3rd there’s r = 1o, 2o, or 3o alkyl, aryl, vinylic X = Cl, Bayerischer rundfunk, or I

O C

OH C

1 . RMgX, ether 2 . H3O+

+

R

HOMgX

Mechanism

Um C Ur

O C

R

H3O+

OH C R

carbonyl compound

alkoxide intermediate

alcoholic beverages

- Grignard reagent provides for a nucleophilic carbon anion, or perhaps carbanion; the addition of the Grignard is similar to the addition of a hydride

Formaldehyde Reaction

MgBr Um

+

L

1 . Blend

H

CH2OH

C

2 . H3O+

cyclohexylmagnesium bromide

chemical

cyclohexylmethanol (65%)

Aldehyde Effect

CH3 H3C C L O CH2 CH

MgBr

+

1 . ether solvent r installment payments on your H3 O+

CH3 H3C C L

OH CH2 C They would

3-methylbutanal

phenylmagnesium bromide

3-methyl-1-phenyl-1butanol (73%)

Ketone Reaction

Um OH CH2CH3

1 . CH3CH2MgBr, ether installment payments on your H3O+

cyclohexanone

1-ethylcyclohexanol (89%)

Ester Effect

O CH3CH2CH2CH2 C OCH2CH3

1 . 2(CH3MgBr), ether installment payments on your H3O+

OH CH3CH2CH2CH2 C CH3 CH3

ethylpentanoate

2-methyl-2-hexanol (85%)

+ CH3CH2OH

Limits of Grignard Reagents

-- Grignard reagent cannot be prepared from a great organohalide in the event there are additional reactive functional groups inside the same molecule - this kind of limits the structures from the products

Bayerischer rundfunk

molecule

FG

- Grignard cannot be built where FG =

sama dengan -OH, -NH, -SH, -COOH

O CH,

C D, O CR, O CNR2 SO2R

protonate Grignard

Therefore, water is a problem!

=

adds to Grignard

NO2,

Our Grignard Reaction

O O C OCH2CH3

HO WOW

O

O

O C OCH2CH3

PhMgBr Et2O

one particular (IR)

2 [IR, NMR (provided on web)]

To

O

OH C Ph level Ph

H3O+

O

WOW C Ph Ph

To

Ph C PH

three or more [IR, NMR (provided on web)]

some

5 [IR, NMR (determined)]

Protecting group (add step 1 to a couple of, remove step 3 to 4): - permits a molecule with several active centers to undergo response selectively at one centre while departing the various other center in one piece

Procedures and Precautions

Part A (Day 1): Security of Ketone (Formation of Ketal)

1) react ethyl acetoacetate with ethylene glycol to produce ketal

Note: uses Dean-Stark snare - azeotrope: liquid combination with regular boiling level (e. g. hexane-water)

2) transfer to separatory direct and isolate/dry organic level 3) separate product (rotary evaporator): MARCHAR, NMR (on web), TLC (later), megapixel

Procedures and Precautions

Parts B & C (Day 2): Preparing of Phenyl Magnesium Bromide/Grignard Reaction 1) weigh out magnesium turnings and grind to expose metal 2) add magnesium to a dry out, three-necked flask with fondre 3) flame dry the apparatus (start at the bottom and work your path up)* Note: must make use of drying Drierite (drying tubes) 4) enable to awesome, start normal water running, through adding bromobenzene, put ether (drop) Note: onset of reaction can be appearance of bubbles in metal 5) reflux for 20 min., cool in ice bath, and instantly add ketal 6) blend for 40 min. through adding ice to quench the reaction 7) work-up reaction employing extraction and re-crystallization 8) characterize: IR, NMR (on web), TLC (later), mega-pixel

Apparatus for Grignard Response

Procedures and Precautions

Parts D & E (Day 3): Ketal Hydrolysis and Column Chromatography 1) reflux tertiary alcoholic beverages in acetone and HCl solution 2) work-up response by way of a great extraction (note: separatory funnel) 3) characterize: IR, NMR, TLC (later), mp 4) purify final product by using column chromatography i) build the column (TA will provide lots of instruction) ii) elute the line using hexane: ether solution (16 Г— 150 mm test tubes) iii) measure the fractions employing TLC iv) visualize dishes using UV (line) and...