Lab 6 Wittig

POST-LAB REPORT

XiaoYing Lu Lab 6: Wittig

 

9/30/2016

Obsera!ions :

1. The wittig wittig mixture mixture became a thick thick paste from from putty-yello putty-yellow w color after after a few minutes minutes of grinding. grinding. It indicates the wittig reaction successfully formed.

2. The off-whit off-whitee solid was collected collected through through the filtratio filtration n from a Hirsch funnel after after few millilit milliliters ers of deionized water was added to the thick paste. It indicated the off-white solid has no more potassium  phosphate but its its still not pure yet because it consists mainly mainly of the trans! trans isomer and some of the cis! trans isomer as well.

"a!a:

"ctual yield of purified trans! trans product # $.$%1&g ! theoretical yield # $.1%&' g ( yield # )actual yield* theoretical yield+ x 1$$ # )$.$%1&g* $.1%&' g+ x 1$$ # &,.$ ( °

°

°

elting point of the product # 1/1 0 -1/2 0 )literature! 1/1 0+

Pos!-#ab $ues!ion: °

1% T&ere is an a''i!iona# iso(er o) 1*+-'i,&en#-1*3-bu!a'iene .(, 0 * &i& &as no! been s&on in !&is e4,eri(en!% "ra !&e s!ru!ure an' na(e i!% 5& is i! no! ,ro'ue' in !&is e4,eri(en! .7in!: T&e inna(a#'e&'e &as !rans s!ereo&e(is!r%

This is a is-is 1*+-'i,&en#-1*3-bu!a'iene . ormation of this isomer is probably preented by s!eri &in'rane  at the ends of the 3-shaped structure because of the two pheny l groups arwe in the same side of the  plane so it doesn4t form readily. readily.

2% 5& s&ou#' !&e !rans* !rans iso(er be !&e !&er(o'na(ia## (os! s!ab#e one

" trans! trans! trans isomer is thermodynamically most stable than others due to the #oering o) s!eri in!era!ions  in a trans isomer )(ore se,ara!ion  between substituents on ad5acent atoms+. 6o it on)ron!s #ess e#e!ron re,u#sion and the di-trans system is actually the #oes! energ  geometry in this system.

3% A #oer ie#' o) ,&os,&oniu( sa#! is ob!aine' in re)#u4ing ben8ene !&an in 4#ene .E4,eri(en! 39A% Loo u, !&e boi#ing ,oin!s )or !&ese so#en!s* an' e4,#ain & !&e 'i))erene in boi#ing ,oin!s (ig&! in)#uene !&e ie#'%  °

°

7enzenes boiling point is 8$.1 0 while xylenes boiling point is 1&8. 0. 9ylene has a higher boiling point than benzene thus its reaction would be carried out at a higher temperature. Higher temperature means faster reaction and it allows the actiation energy to be easily oercame and forms more product. +% Ou!#ine a sn!&esis )or is an' !rans s!i#bene .!&e 1*2-'i,&en#e!&enes using !&e 5i!!ig rea!ion%

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&!!,://%&egg%o(/&o(eor-&e#,/
&!!,s://%&egg%o(/&o(eor-&e#,/