joyman (Stranger)
10-23-01 09:28
No 228060
      Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Swim is dreaming about going from benzaldehyde to benzyl alcohol using the (cross -) Cannizzaro reaction and then to  BzCL by reacting the BzOH with HCL.

He is interested if - instead of extracting the bzOH in ether as a separate step, whether just adding HCL to the mix after the Cannizzaro has done its job would yield the desired product.

HCL would neutralise the alkali and hopfully convert the BzOH to bzCL. This second step has already been discussed at the hive (BzCL will separate out as an extra layer on top of the aqueuous layer when BzOH is shaken with HCL - cold).

Would the remaining formaldehyde left over be likely to prevent this step? Or the neutralised alkali ie NaCL or KCl? Swim feels this might represent a different method to separate out the product and is not necessarily adopting a lazy approach by avoiding the intermediate step of extracting the BzOH with ether.

Note on the Cannizzaro reaction -
If you have benzaldehyde in aqueous base, it will react to generate benzoic acid and benzyl alcohol.  This is essentially irreversible. The aldehyde undergoes simultaneous oxidation and reduction to form an alcohol and a carboxylic acid. The addition of formaldehyde gives a Cross-Cannizzaro reaction which shifts the reaction balance so that benzyl alcohol is formed at the expense of benzoic acid. Its done cold.
(Hive Bee)
10-23-01 23:09
No 228232
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Sounds What is the ratio of aqueous base to formaldehyde?  That is the question that will lead you to your answer young jedi.  Neutralizing the base and increasing the ionic strength of your solution certainly should help.tongue

something for your mind.......
(Hive Bee)
10-24-01 03:24
No 228286
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

I've been this lazy once and can advise you against it.
What will happen?
For the Cannizzarro you'll need strong (35-50%) NaOH solution.
If you want to react the produced BzOH to BzCl you'll need strong HCl.
Adding strong HCl to your Cannizzarro reaction mixture will produce a lot of NaCl, some Benzoic acid and water. By the time all is neutralised there will be so much water that adding enough HCl to get the concentration needed for the BzCl conversion is not practical.

Hansje high in proteine and fibre!
(Distinctive Doe)
10-24-01 14:32
No 228452
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

HCl is cheap.
Neutralize the basic solution until slightly acidic, extract the BzOH with organic solvent(toluene?), then perform the second reaction.

Could toluene --> BzCl possibly be easier?
Also starts with an easily available precursor.

Here is some helpful info

Producing Benzyl chloride

Benzyl chloride.    
Niki, Senji.  (Japan).    Japan. Kokai  (1977),
JP  52111520  Patent  written in Japanese.

Cl (146 kg) was introduced into a mixt. of 330 kg PhMe and 3 kg red P over 9 h at 90-5.5° and the mixt. stirred 1 h to give 172 kg PhCH2Cl (purity 99.5%).

Synthesis of benzyl chloride by solid-liquid phase-transfer catalysis method.    
Bui Thi Van Nga; Chu Pham Ngoc Son.    Dai Hoc Tong Hop Thanh Pho,  Ho Chi Minh,  Vietnam.   
Tap Chi Hoa Hoc  (1985),  23(4),  6-7. 
CODEN: TCHHDC  ISSN: 0378-2336.  Journal  written in Vietnamese.    CAN 105:193306    AN 1986:593306

PhCH2Cl  [100-44-7] was prepd. by chlorination of PhMe  [108-88-3] with Ca(OCl)2 using tetrabutylammonium hydrogen sulfate  [32503-27-8] or tetrabutylammonium bromide  [1643-19-2] as phase-transfer catalysts.  With suitable ratio of PhMe-catalyst, the yield was high and the reaction was quite selective. 

Toluene derivatives chlorinated in the side chain.
Besta, Josef; Soulek, Miroslav.  (Czech.).    Czech.  (1979),     2 pp.  CODEN: CZXXA9  CS  179600  19790715  Patent  written in Czech.  

Chlorination of PhMe at 20° in the presence .apprx.0.1% (HOCH2CH2)3N (I) gave a mixt. of PhCH2Cl, PhCHCl2 and PhCCl3.  Ring chlorination was also suppressed in the presence of I and Fe3+. 

Studies in catalytic reactions of carbons.  Part X.  Catalytic chlorination of benzene and toluene at ambient temperature in the presence of activated carbons.
Puri, Balwant Rai; Singh, D. D.; Kaura, N. C.; Verma, S. K.      
Indian J. Chem., Sect. A  (1980),  19A(2),  109-12.
CODEN: IJCADU  ISSN: 0376-4710.  Journal  written in English.   

Activated C catalyze conversion of C6H6 to PhCl and Cl2C6H4 and that of PhMe to PhCH2Cl on passing Cl through C6H6 or PhMe contg. C in suspension at 25°.  The catalytic performance of a C for chlorination of PhMe is enhanced on generation of unsatd. sites on the catalyst either by giving small burn-offs or carrying out surface oxidn. followed by evacuation.  The mechanism involves the adsorption of the reactants at unsatd. and other active sites on the surface of C.  Chemisorption of Cl during the process leads to deactivation of the C catalysts.  The catalytic activity of a C sample is restored on treatment with a H2 current at 500°.

Studies in catalytic reactions of carbons:  Part VII.  Catalytic chlorination of toluene in presence of active carbons.    
Puri, Balwant R.; Singh, D. D.; Verma, S. K.   
Indian J. Chem., Sect. A  (1978),  16A(12),  1026-9.  Journal  written in English.   

The optimum temp. for the title chlorination reaction to give PhCH2Cl is in the 250-400° range.  The catalytic performance of a carbon at its optimum temp. varies not so much with surface area as with surface unsatn.  Catalytic activity can be enhanced by generation of addnl. unsatd. sites by suitable treatments.  The reaction involves dissociative chemisorption of Cl at the unsatd. and other active sites and interaction of toluene vapor with some of the Cl atoms released from the surface under the sweeping action of the gas at elevated temps.  As the surface gets increasingly blocked by chemisorbed Cl, the catalytic efficiency falls but can be revived on desorption of Cl by treatment in a current of H2 at 500°.

Benzyl chloride.    
Varshaver, E. V.; Kruglova, T. P.; Razumovskii, Yu. V.; Sumin, M. S.; Uskov, V. Ya.  (USSR).    U.S.S.R.  (1979),     CODEN: URXXAF  SU  644769  19790130  Patent  written in Russian.   

PhCH2Cl was prepd. by chlorination of PhMe at 75-85° in the presence of azobisisobutyronitrile (I) contg. HCONH2 (0.1-0.3 wt.% based on MePH).  A 1:2-3 wt. ratio of I-HCONH2 was used to increase the MePh conversion and selectivity to PhCH2Cl.

New catalytic synthesis of benzyl chloride.    
Tang, Xun; Shi, Guojun; Liu, Pingmin.  
Xiandai Huagong  (1997),  17(2),  23-25. 
CODEN: HTKUDJ  ISSN: 0253-4320.  Journal  written in Chinese.    CAN 127:331230    AN 1997:694942

Synthesis of benzyl chloride by catalytic chlorination of toluene with a composite catalyst was reported.  The yield of benzyl chloride based on toluene was 92%.  The process is superior to thermal-chlorination and photo-chlorination processes.

Highly selective chlorination of toluene to benzyl chloride.
Xu, Zhen.    Washington Univ.,  St. Louis,  MO,  USA.  Avail. UMI, Order No. DA9918677.    (1998),     249 pp.
From: Diss. Abstr. Int., B 1999, 60(2), 747.  Dissertation  written in English.    CAN 131:300731    AN 1999:445826

Distillation of benzyl chloride.   
Boeckmann, Walter.  (Farbenfabriken Bayer A.-G.).   
US  3715283  19730206  Patent  written in English.

Decompn. of PhCH2Cl (I) on distn. of I or mixts. contg. I, esp. in the presence of metal traces, was reduced by addn. of 0.01-1.0% lactams.  Thus, on distn. of I from a tech. mixt. of PhMe with aromatic halides with addn. of 0.01-0.05% e-caprolactam, no measurable decompn. of I was obsd.

The decompn. of PhCH2Cl during its distn. or the distn. of its mixts. which is greatly promoted by Fe compds. is strongly inhibited by carrying out the distn. in the presence of a lactam (e.g., 2-pyrrolidone, caprolactam).  Thus, 96 wt. % PhCH2Cl is decompd. in 90 min at room temp. when FeCl3 is added to it.  With 1.0 wt. % 2-pyrrolidone additive the same decompn. at 95° in 90 min is 13%. 

Do Your Part To Win The War
10-25-01 23:35
No 228938
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Thanks to the Bees for their help.

One way to possibly increase the ionic conentration would be by driving off some of the h20 and formaldehyde by evap and heating. (imagine the smell from the formaldehye!). Probably more straight forward to extract with a solvent. 

Foxy - I have sort of been ignoring the toluene thing since requires chlorine generator and have heard of mixed success with UV - mercury vapour lamp etc (Been considering setting up the welder with a carbon arc). However youve got a lot of great refs there that i hadnt seen before so might need a bit more investigation - Thanks.
(Distinctive Doe)
10-25-01 23:55
No 228947
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

With proper ventalation a chlorine generator is easy.

And considering the scale matchbox RedP could make ALOT of BzCl without to much trouble.

Here are details of chlorine generation, look down the page
../rhodium/chemistry /mercurychloride.html

Do Your Part To Win The War
10-26-01 00:24
No 228958
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Yes I am seeing what you mean - timeframe here would also allow a chlorine generator to work great. Very very interesting ref.   
(Hive Bee)
10-26-01 06:57
No 229031
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Why bother with chlorine or exoctic chemicals? This is all you have to do:

100 ml BzOH mixed with 200ml 31% HCl, 200g CaCl2. Stirred for 32hours at room temp. 90ml crude BzCl seperated from top of mixture (no extraction required).
This is about 100g crude product! Just mixing, stirring, seperating, Isn't that good!

For a full discussion see Post 71906 (uemura: "Easy Benzylchloride Synthesis", Methods Discourse)!
P.S. Do not wash the BzCl with H2SO4!! Read the whole thread!
Carpe Diem
(Hive Bee)
10-26-01 07:26
No 229041
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Yes, check out my findings of benzal/benzyl chloride in a
patent -
post no: Post 224026 (encopo: "Re: Biosynth (homebrewing E)", Serious Chemistry)
patent #: U.S. Pat.#1,280,612

Don't mind me. I'm mentally ill.
(Distinctive Doe)
10-26-01 08:47
No 229054
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Why bother?

Because toluene, Red P and Chlorine can be gotten very easily otc.  Within 1 km of me right now there is enough of the above to produce multi kilograms of BzCl.  I don't think BzOH is as easily available.

Are you positive Lava lamps contain it??
I am not convinced based on reading lots of google search results.  You can make a lava lap with BzOH, but are the commertial ones BzOH?  Anyone know if the Lava Lamps(TM) contain BzOH? PM me if you know.

Do Your Part To Win The War
10-26-01 09:00
No 229057
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   


Swim was trying to go benzaldehyde -> benzyl chloride and
not benzyl/benzal chloride -> benzaldehyde.

(Hive Bee)
10-26-01 11:58
No 229094
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Because toluene, Red P and Chlorine can be gotten very easily otc This is indeed a good reason! smile Uemura also seeks for minimal efforts/costs and risks.

With respect to joymans questions however, Uemura believes that the crossed cannizarro (*), then the above BzOH->BzCl path is the easiest (**).
Carpe Diem.
(*) Uemura doesn't have easy access to formaldehyde but it's easy to get BzOH and Benzaldehyde.
(**) Ohh, to bee honest, Uemura has never opened or used a lava lamp and checked if it contains BzOH. Other bees should be more experts than him.
(Hive Bee)
10-28-01 15:41
No 229690
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Jeeeeeeezzzzz, I don't fookin beeelive this!!! Swill blush has just synth'd this the other way round! BzCl > aldehyde, via Sommlet rxn, Vogel's 5th exp. 6.119 p2002.  Yeild looks like… plenty, not washed and brushed up yet. It's clear though, smells… amaretto.

Joyman, d'y just wanna swap my 2l BzCl for your aldehyde?cool

Linoleum: the 13th element!  Now available at all good DIY stores… & Walmart.
(Hive Bee)
10-28-01 22:56
No 229832
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

Read the post again - it's not Benzyl chloride to Benzaldehyde,

it's Toluene -> Benzyl/Benzal Chloride (given amount
of Ca(OCl)2 used).

then an optional boil in alkaline water to yield benzaldehyde.

This seems to be a MUCH easier way of making benzyl/benzal
chloride or benzaldehyde than using RP, chlorine gas &
toluene. Chlorination via Ca(OCl)2 is very effective,
as shown in the patent.

Check it out. If you like almond cakes, make benzaldehyde
and add it to your recepie :-)

Don't mind me. I'm mentally ill.
10-29-01 21:10
No 230316
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

you go toluene -> bzcl -> phcho
you are obviously referring to the first bit.

i didn't like the look of the pool shock thing since there seemed to be a big work up involved to get anhydrous pool chlorine. also think it still needs the uv for good yields.

Hell man, id gladly do the trade. (2 kgs !! you bastard)  BzCl has the status of p2p where swim lives. pure benzaldehyde is also illegal to buy or sell. Almond essence seemed to me to be a good source. swim reckons you've got more options with bzcl than phcho which locks you into the nitro ethane thing. These simple chems are really hard to obtain - it feels silly that it requries this much work to make them. 


10-29-01 21:56
No 230351
      Post deleted by Rhodium  Bookmark   

10-29-01 22:36
No 230371
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   


i think that the answer is that apparently with toluene ring substitution is not favoured so long as the temperature is kept low.
(Distinctive Doe)
10-30-01 09:46
No 230524
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

i didn't like the look of the pool shock thing since there seemed to be a big work up involved to get anhydrous pool chlorine. also think it still needs the uv for good yields.

NO UV!!!!  There is very strong evidence that UV with the pool shock reaction goes BOOM! That means no sunlight for this reaction unless you like explosions.

The thing I like about the RedP/Chlorine procedure is the near quantitative yeild which will make the work-up a BREEZE.

Do Your Part To Win The War
10-30-01 09:57
No 230528
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   


I think the RP/chlorine is really quite brilliant. Its a great discovery.laughlaughlaugh
Looks like the solution for easy otc bzcl - swims extremely grateful. laughlaughlaugh
12-26-01 10:54
No 250577
      Re: Benzaldehyde -> Benzyl Chloride (cold)  Bookmark   

would it be possibel to recycle the phospher so that when the chlorination of the toulene was  done the benzyl chloride was simply destilated  of trough some CaCl2 and the RP/PCl5 recovered in the chlorination flask was then again recycled for the next batch of toulen.