Ce qui fait que I'ancien bandagiste renie
Le compioir dont le faste alléchait les passants,
C'est son jardin d'Auteuil, ou, veufs de tout encens,
Les Zinnias ont I'air d'être en tôle vernie.
Hi Bees!
How about making a neet DOX-series precursor (2-allyl-1,4-dimethoxy-benzene or it's isomer) from p-methoxy-phenol? This potential route came to me yesterday while I was reading books and drinking a glas of wine.
Preparation of 2-allylphenol followed by isomerisation (a la safrol to isosafrol) is a well known, classic reaction, described in most practical org. chem. course books.
Can someone please follow below proposed procedure and report the results, that would bee super-great! I'm myself unable to preform this synth right now, yet I'm dying to know if it would work as planned as soon as possible. A true researcher can even take this to higher level and obtain some asymmetric ethers, like 2-ethoxy-5-methoxy[5] just to name one, that would bee fun. The precursor described herein is perfect for that purpose!
Bandil, I was thinking about you when I came up with this! Wouldn't this bee a nice project for you since you are interested in DOX family! Have fun Bandil!!!
Outline:
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000428230-file_2nr2.gif)
Experimental:
[1]:
ATTENTION: Instead of using 47 g of phenol as described below, use 62 g of 4-methoxy-phenol and proceed! The product should bee 1-Allyloxy-4-methoxy-benzene. Distill under the reduced pressure and record the yield and the b.p.
Place 47 g (0.5 mol) of phenol, 60.5 g (0.5 mol) of allyl bromide, 69.1 g (0.5 mol) of anhydrous potassium carbonate and 100 mL of acetone in a 250-mL, two-necked round-bottomed flask fitted with a reflux condenser and sealed stirrer unit, and boil on a steam bath for 8 hours with stirring. Pour the reaction mixture into 500 mL of water, separate the organic layer and extract the aqueous layer with three 20 mL portions of ether. Wash the combined organic layer with 2 M sodium hydroxide solution, and dry over anhydrous potassium carbonate. Remove the ether with a rotary evaporator and distil the residue under reduced pressure. Collect the allyl phenyl ether, b.p. 85°C/19 mmHg; the yield is 57 g (85%).
[2]:
ATTENTION: Use 61.2 g of 1-Allyloxy-4-methoxy-benzene MW = 164 g/mol instead of allyl phenyl ether and proceed! Record the yield and b.p.
Boil 50 g of allyl phenyl ether gently in a RB flask fitted with an air reflux condenser. Determine the refractive index of the mixture at intervals; the rearrangemant is complete and the boiling is stopped when the refractive index has risen to 1.55 (about 6 hours are required). Dissolve the product in 100 mL of 5 M sodium hydroxide solution and extract with two 30 mL portions of light petroleum (b.p. 40-60°C) which removes the small amount of 2-methyldihydrobenzofuran formed as a by-product and which is neutral. Carefully acidify the alkaline solution with 5 M HCl (aq) with cooling and extract the mixture with one 50 mL portion and two 25 mL portions of ether. Dry the extract over anhydrous sodium sulphate and remove the ether with a rotary evaporator. Distil the residue under reduced pressure to give 2-allylphenol, b.p. 103-106°C/19 mmHg or b.p. 96°C/13 mmHg; refractive index 1.5440. The yield is 35 g (70%).
[3]:
ATTENTION: Instead of using 20 g p-hydroxybenzaldehyde as described below, use 26.9 g of 2-Allyl-4-methoxy-phenol and proceed! The product should bee 2-Allyl-1,4-dimethoxy-benzene. The yield should bee excellent. Record the yield!
20.g of p-hydroxybenzaldehyde (0.164 mol) was reacted with 29.0 g of dimethyl sulfate (0.230 mol) and 22.0 g of sodium carbonate (0.20 mol) for 2 hr. at 75°-80° C. A total of 12 ml of water was added in small portions over the last hour. Work-up by addition of water, acidification and benzene extraction yielded 22.27 g of p-methoxybenzaldehyde (99.9%).
Patent US4065504 (http://l2.espacenet.com/dips/viewer?PN=US4065504&CY=gb&LG=en&DB=EPD)
[4] (Optional, isomerisation):
ATTENTION: Use 26.7 g of 2-Allyl-1,4-dimethoxy-benzene MW = 178 g/mol instead of 20 g of 2-allylphenol and proceed. Record yield and b.p.
Prepare a saturated solution (about 50% w/v) of potassium hydroxide in 60 mL of methanol. Place this solution together with 20 g of 2-allylphenol in a RB flask fitted with a still-head and condenser set for downward distillation. Arrange a thermometer so that the bulb dips into the mixture and distil the latter slowly until the temperature reaches 110°C. Remove the still-head, attach an air condenser to the flask and boil the reaction mixture gently under reflux for 6 hours. Cool the mixture, cautiously acidify with concentrated HCl (aq) and extract the product with tree 30-mL portions of ether. Dry the extract, remove the ether and distil the residue under reduced pressure. Collect the 2-(prop-1-enyl)phenol as a fraction, b.p. 100-115°C/15 mmHg; it crystallises on cooling in an ice bath; yield 15 g (75%). Recrystallisation from dry light petroleum (b.p. 60-80°C) gives shining needles, m.p. 37°C.
[5]:
Diethyl Sulphate
This can bee found on rhodium.ws...
Ninety grams of sodium sulfate is placed in a dry 1 liter flask connected with a condenser and a receiver arranged for vacuum distillation. The flask is heated by means of an oil bath to 155-165°C. The apparatus is exhausted as nearly as possible by means of a filter pump, and misture of 50 grams of ethanol and 104.5 grams of concentrated sulfuric acid is allowed to drop through a capillary tube on the sodium sulfate at a rate of 120-150 drops per minute. The distillation of the mixture requires about one and one half hours for completion. The distillate, which consists of ethanol and diethyl sulfate is poured into a separatory funnel, the ethanol may be recovered for further use. The diethyl sulfate is washed with a dilute solution of sodium carbonate and then several times with cold water, then dried with anhydrous sodium sulfate, yielding 32.4 grams.
JACS 46, 999-1001 (1924)
References:
[1] Vogel's 5:th, page 986
[2] Vogel's, 5:th, page 984
[3] Us patent 4065504
[4] Vogel's, 5:th, page 984
[5] www.rhodium.ws
but someone had it before: https://www.thevespiary.org/rhodium/Rhodium/chemistry/25.meo.allylbenzene.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/25.meo.allylbenzene.html)
:)
for possible allyl iodide preparations see also this thread: Post 402920 (https://www.thevespiary.org/talk/index.php?topic=6975.msg40292000#msg40292000)
(hypo: "allyl iodide: is this article useful?", Chemistry Discourse)
Hey pH:
Look here Post 406068 (https://www.thevespiary.org/talk/index.php?topic=11698.msg40606800#msg40606800)
(Rhodium: "For 2,5-Dimethoxyallylbenzene prep", Novel Discourse)
And synth allyl bromide instead of the iodide, it is easier.
Glycerol -> allyl alcohol
https://www.thevespiary.org/rhodium/Rhodium/chemistry/allylalcohol.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/allylalcohol.html)
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0042 (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0042)
allyl alcohol -> allyl bromide
(A) ALLYL BROMIDE, CH2=CHCH2Br
In a 3-l. round-bottomed flask, a hydrobromic acid solution is prepared (p. 26) by the sulfur dioxide reduction of 480 g. (150.5 cc., 3 moles) of bromine in the presence of 510 g. of ice water or a mixture is made of 1 kg. (5.9 moles) of aqueous 48 per cent hydrobromic acid and 300 g. (162 cc.) of concentrated sulfuric acid. To this is added 385 cc. of aqueous allyl alcohol (p. 42), which, according to bromine titration, contains 233 g. (4 moles) of pure allyl alcohol. The 3-l. round-bottomed flask is fitted with a mechanical stirrer (Note 11), separatory funnel, and an efficient condenser set for downward distillation. Stirring is started, and 300 g. (162 cc.) of concentrated sulfuric acid is added gradually through the separatory funnel to the warm solution. The allyl bromide distils over completely in about one-half to one hour. The crude allyl bromide is washed with dilute sodium carbonate solution, dried over calcium chloride, and then distilled. The yield of product boiling at 69–72° from a number of experiments varies from 445–465 g. (92–96 per cent of the theoretical amount). A small high-boiling fraction is also obtained and examination has shown this to consist of propylene bromide.
from http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0025 (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0025)
If you wanna use allyl chloride, it is synthetised easily from allyl alcohol + HCl(aq) + CuCl(cat); the allyl chloride separate directly and is decanted in quantitative yield.