05-07-03 11:07
No 431957
Raf thought he'd isomerize some safrole via known routes.Eleusis says CaO/KOH procedure isn't scaleable,i say it is.
500 grams of maybe 95% pure safrole was heated in a 1 liter RB flask.When safrole started to boil,5 grams of KOH and 50 grams of CaO was added.Over short period of time temp climbed to 252 C and heating was discontinued.Reaction mix was let to cool.It was then vacuum filtered and filtrate was distilled under vacuum to yield 395 grams of isosafrole which was tested for bp at atmosperic pressure and termometer indicated that nothing distilled over below 244 or so degrees and temp slowly went up as fluid came over.Yielded isosafrole looks and smells like isosafrole and will be oxidised tomorrow.Total yield 79%.
For those about to synth,we salute you
(Stoni's sexual toy)
05-08-03 06:53
No 432138
Vac reflux works great for 1L amounts, more if you use good stirring or introduction of a stream of air with a capillary. Yields will be above 90, when doing it at that scale even close to quantitative.
I'm not fat just horizontally disproportionate.
http://www.whatreallyhappened.com
(Hive Addict)
05-08-03 07:54
No 432150
No magnetic stirring apparatus over here available,only for very high cost and even then getting one is hard.Anyways raf is isomerizing at the moment.DCM used was pro Analysi ACS grade,it was bit expensive(20$ a litre) but overall cost is about same as when stripped out of stripper and stripper DCM is nearly as pure.Couldn't get "dirtier" DCM so had to use the best...
For those about to synth,we salute you
(Hive Bee)
05-14-03 15:49
No 433208
Did you have trouble filtering, and did you heat the CaO in the oven first?
Regards,
FF
Be joyful, though you've concided the facts!
(Old P2P Cook)
05-14-03 21:50
No 433253
did you heat the CaO in the oven first?
I don't see that that would do anything for you. If the CaO has been slaked then I don't think that oven temperatures are going to be enough to quicken it.
All those moments will be lost in time, like tears in rain.
(Hive Addict)
05-15-03 06:47
No 433334
CaO used was reagent grade,str8 from the bottle.
For those about to synth,we salute you
(Hive Addict)
05-15-03 17:26
No 433427
why even use CaO? all it does, unless I'm mistaken, is remove water from the reaction, so if you heat th KOH and drive off all the water, it should be fine without the CaO, or am I wrong?
It is seductive, way too seductive. -Eleusis
(Hive Bee)
05-15-03 17:37
No 433434
I just tried the CaO deal with 2% KOH on my 3-Phenyl-1-Propene. No temp rise, no conversion. I've tried it with straight 2% KOH, evaporating first, No conversion. I've even tried it with 3M KOH in BuOH, drying by distilling the azeoptope first. Nothing. I just can't isomerise it!
Regards,
FF
Be joyful, though you've concided the facts.
(Stoni's sexual toy)
05-16-03 00:49
No 433494
How do you know that no isomerisation took place?
I'm not fat just horizontally disproportionate.
http://www.whatreallyhappened.com
(Hive Addict)
05-16-03 16:06
No 433624
How do you know you have the allylbenzene in the first place?
It is seductive, way too seductive. -Eleusis
(Hive Bee)
05-17-03 20:16
No 433821
Well, I don't really know for sure. Maby it's not! I made the allylbenzene with Allylbromide via Friedels-Craft. I've distill it a number of times now and it always comes over at 158°C. What else could it be? If it was isomerised it would boil at around 172°C.
Regards,
FF.
(Chief Bee)
05-18-03 11:10
No 433974
What was your yield of allylbenzene with friedel-crafts alkylation, and which procedure did you follow?
(Hive Bee)
05-19-03 03:12
No 434131
The proceedure I followed was takes from:
"The Action of Allyl Alcohol on Benzene in the presence of Alluminium Chloride"
Huston, RC., et al.,J Am. Chem. Soc., 48, p1955 (1926).
I used 368.5g (3.06 mol) Allylbromide and my yield was 64.5g (0.55 mol) supposed Allylbenzene. 17.9%. Dead end.
Raf, I think I've hijacked your post. Sorry.
Regards.
FF
Be joyful, though you've concided the facts!
(Chief Bee)
05-20-03 16:23
No 434405
(Rated as: excellent)
This is the procedure from the journal you referenced, where they cook up three batches each using 87g of allyl alcohol (= 261 g/4.5 mol in total), then combines the high-boiling distillates from those three and isolate 45g (0.38 mol) of allylbenzene boiling at 105-165°C from it by fractional distillation. That's only a 8.5% yield, so it seems like you got twice that by using allylbromide instead.
Allylbenzene from Allyl Alcohol, Benzene and Aluminum Chloride
87 g of allyl alcohol, bp 95-97°C, was dissolved in 585g of benzene and the solution stirred constantly during the addition of 99 g of aluminum chloride. The addition of the chloride took, in general, from two to three hours, during which time the temperature was maintained at 20-25°C The stirring was continued for about eight hours, while the mixture gradually became dark reddish-brown.
The next morning it was decomposed with ice and dilute hydrochloric acid. The benzene layer was separated and the aqueous portion extracted thrice with ether. The ether was distilled and the residue added to the benzene portion. This was fractionated with a 20cm column, 510 g of benzene and 30 g of allyl alcohol were recovered from those portions which came over below 105°C. The residue weighed 28 g. This was combined with the products of two other runs, and fractionated eight times. The fractions obtained were as follows: 105-165°C 45g; 85-105°C (18mmHg) 10 g; 105-135°C (18mmHg) 1g; 135-170 (18mmHg) 14.5g; tarry residue 14 g. Practically all of the fraction boiling at 105-165°C (746mmHg) proved to be allyl benzene (bp 157-159°C).
In order to verify the identification, 4g of allylbenzene was heated on the water-bath with 8g of potassium hydroxide in 80mL of 95% alcohol for three hours. Most of the alcohol was then distilled and 250 mL of water added. After the solution was neutralized with hydrochloric acid, it was extracted with ether. The ether was distilled and the propenylbenzene treated in chloroform solution with 2 mL of bromine. After two crystallizations from alcohol the 1,2-dibromopropylhenzene melted sharply at 66-66.5°C.
The 85-105°C (18 mmHg) fraction came over after repeated distillation at 90.5-92.5°C (18mmHg). When distilled under atmospheric pressure it had the correct boiling point for 2-chloropropylbenzene, 205-207°C [JCS 52,35 (1887)].
A determination of chlorine (Carius) gave 21.75%. When boiled with dil. nitric acid (10%) it gave p-nitrobenzoic acid (mp 237-238°C) the methyl ester of which melted at 96°C. Oxidation with potassium permanganate gave benzoic acid.
The fraction boiling at 135-170°C (18mmHg) did not give a sharp boiling point after ten distillations. A Carius determination for chlorine gave 5.53%. The entire fraction was dissolved in 50 mL of ether, the solution treated with 1 g of finely chipped sodium and refluxed on a water-bath for four hours. The mixture was filtered, the ether evaporated and the residue fractionated. After three distillations 6.5 g. came over at 277-280°C (745 mmHg). Its properties were those of a saturated hydrocarbon. It is probably 1,2-diphenyIpropane, C6H6-CH2CH2-C6H6 [Compt Rend, 139, 1482 (1904)].
Reference: J Am. Chem. Soc. 48, 1955-1959 (1926)