http://rdf.ncbi.nlm.nih.gov/pubchem/patent/GB-761542-A
Outgoing Links
| Predicate | Object |
|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_a4ce383863936b99d0014e07e769c47b |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C07C47-16 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/C07C47-16 |
| filingDate | 1953-02-06-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationDate | 1956-11-14-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | GB-761542-A |
| titleOfInvention | Improvements in or relating to the method of manufacturing chloral from paraldehyde |
| abstract | The production of chloral comprises chlorinating paraldehyde in an anhydrous menstruum, in order to convert the major portion of paraldehyde to hexachloroparaldehyde, wherein each mol. of paraldehyde is treated with from more than 3 to 7 mols. of chlorine at a temperature within the range 15 DEG to 60 DEG C. and the reaction product is chlorinated in an aqueous menstruum to depolymerize the chlorinated paraldehyde. To obtain pure chloral, the chloral hydrate so obtained is washed with an aqueous solution of sulphuric acid the strength of which is such that the sulphuric acid layer contains more than 70 per cent H2SO4 after the washing. Chloral and the reaction product of the anhydrous chlorination of paraldehyde are suitable for use as the liquid menstruum for the anhydrous chlorination step. It is advantageous to use an excess of chlorine in amounts from 5 to 10 per cent by weight over the maximum of 7 mols. By control of temperature, as much as 5.7 mols. chlorine per mol. of paraldehyde may be reacted at about 35 DEG C. to give a product comprising mainly hexachloro-paraldehyde with some pentachloro- and tetrachloroparaldehyde. In the aqueous chlorination step, the amount of aqueous medium may be varied from 3 to 6-7.5 mols. per mol. of paraldehyde. The aqueous medium may be water or an aqueous solution of an inorganic acid such as sulphuric or hydrochloric acid. The aqueous chlorination may be effected at a temperature within the range of 40-80 DEG C. The chlorine is preferably introduced through a porous plate or other member which breaks up the gas into fine bubbles. The rate of introduction of chlorine is preferably increased as the chlorination progresses, the preferred rate being in the range 0.02 to 0.05 mols. of chlorine per hour per mol. of acetaldehyde, and the reaction being terminated when the quantity of chlorine reacting is less than half to one fourth of the chlorine charged. During the washing of the product with aqueous sulphuric acid, it is preferred to add a proportion of monochlorobenzene. The product may then be given a further wash with 93 to 100 per cent concentrated sulphuric acid. A detailed example is given in which paraldehyde is added in small increments to a first chlorinator containing anhydrous chloral and chlorine addition is balanced to the paraldehyde addition, the temperature being maintained at 35 DEG C.; the product is charged to a second chlorinator with 6 mols. of water per mol. of paraldehyde and chlorine is passed in while the temperature is raised from 40 DEG C. to reflux temperature; the product is washed with aqueous sulphuric acid and then with 100 per cent sulphuric acid. Data are also given for several cycles of chloral production in which one half of the anhydrous product of one cycle is used as the anhydrous menstruum for the next cycle. Specification 668,275 is referred to. |
| priorityDate | 1952-02-06-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
Incoming Links
Total number of triples: 27.