PL115568B2 - Method of p-cyanophenol manufacture - Google Patents

Method of p-cyanophenol manufacture Download PDF

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Publication number
PL115568B2
PL115568B2 PL22060079A PL22060079A PL115568B2 PL 115568 B2 PL115568 B2 PL 115568B2 PL 22060079 A PL22060079 A PL 22060079A PL 22060079 A PL22060079 A PL 22060079A PL 115568 B2 PL115568 B2 PL 115568B2
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Poland
Prior art keywords
cyanophenol
hydroxybenzaldehyde
mineral acid
manufacture
mol
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Application number
PL22060079A
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Polish (pl)
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PL220600A2 (en
Inventor
Waclaw Zamlynski
Mikolaj Jawdosiuk
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Politechnika Warszawska
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Priority to PL22060079A priority Critical patent/PL115568B2/en
Publication of PL220600A2 publication Critical patent/PL220600A2/xx
Publication of PL115568B2 publication Critical patent/PL115568B2/en

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Description

Przedmiotem wynalazku jest sposób wytwarzania p-cyjanofenolu z aldehydu p-hydroksybenzoesowego. p-Cyjanofenol jest stosowany jako zwiazek wyjsciowy w syntezie rozleglej grupy zwiazków cieklokrystalicznych bedacych estrami p-cyjanofenylowymi podstawionych kwasów benzoesowych,zwlafficzap-alkilo-lubp-alkoksy- benzoesowych. Estry te sa nematycznymi substancjami cieklokrystalicznymi stosowanymi w urzadzeniach elek- trooptycznych, zwlaszcza we wskaznikach cyfrowych zegarków i kalkulatorów elektronicznych.Znany jest sposób wytwarzania p-cyjanofenolu z aldehydu p-hydroksybenzoesowego, który poddaje sie reakcji z hydroksyloamina, ewentualnie w postaci chlorowodorku, w obecnosci zasady. Produktem takiej reakcji jest oksym, który nastepnie poddaje sie odwodnieniu za pomoca srodków odwadniajacych. Tradycyjnym srod¬ kiem stosowanym do odwadniania oksymów do nitryli jest bezwodnik octowy.W przypadku stosowania jako substratu aldehydu hydroksybenzoesowego istnieje mozliwosc estryfikacji, która pociaga za soba koniecznosc dodatkowej hydrolizy wytworzonego estru. Sposób taki jest procesem wielo¬ etapowym.Mozna stosowac takze inne srodki odwadniajace, np. kwas p-toluenosulfonowy, dwucykloheksylokarbo- dwuimid. Zawse jednak nalezy wydzielic przejsciowy oksym i zastosowac srodekodwadniajacy. N Nieoczekiwanie okazalo sie, ze jezeli znana reakcje aldehydu p-hydroksybenzoesowego z chlorowodorkiem hydroksyloaminy prowadzi sie w obecnosci kwasu mineralnego, jako produkt uzyskuje sie p-cyjanofenol, anie oksym,jak to ma miejsce w znanych sposobach.Sposób wedlug wynalazku polega na reakcji aldehydu p-hydroksybenzoesowego z chlorowodorkiem hydro¬ ksyloaminy w srodowisku alkoholu alifatycznego w obecnosci 0,5—10% molowych kwasu mineralnego.Sposób wedlug wynalazku pozwala zatem na wytworzenie p-cyjanofenolu bez klopotliwego wydzielania oksymu i dodatkowego jego odwadniania, co j& wyzej wykazano, jest istotnym utrudnieniem znanych sposo¬ bów.Na podkreslenie zasluguje równiez fakt, ze reakcja prowadzona w identycznych warunkach miedzy hydro¬ ksyloamina i aldehydami z innymi podstawnikami niz grupa hydroksylowa, nie daje w efekcie podstawionych benzonitryli lecz oksymy odpowiednich aldehydów. Potwierdza to nieoczekiwany efekt sposobu wedlug wyna¬ lazku.2 115568 Wydajnosc czystego produktu wytworzonego sposobem wedlug wynalazku wynosi 80% pizy uzyciu tech¬ nicznego aldehydu. Po wstepnym oczyszczeniu aldehydu p-hydroksybenzoesowego od barwnych produktów utlenienia straty w procesie oczyszczania p-cyjanofenolu sa nizsze i wydajnosc moze osiagnac 90%. Jako kwas mineralny koizystnie stosuje sie kwas solny. l Sposób wedlug wynalazku jest zilustrowany nastepujacym przykladem.Przyklad. W kolbie kulistej o pojemnosci 1 litra umieszczono 50,3 g (0,05 mola) aldehydu p-hydro¬ ksybenzoesowego, 35 g (0,05 mola) chlorowodorku hydroksyloaminy oraz 300 ml 96% alkoholu etylowego. Do roztworu dodano 3 krople stezonego kwasu solnego i calosc ogrzewano do wrzenia pod chlodnica zwrotna wciagu 12 godzin.Po ochlodzeniu roztwór zatezono,przy czym powstal krzepnacy olej. Olej ten oczyszczono przez krystali¬ zacje z wrzacej wody z dodatkiem wegla aktywnego. Otrzymano rózowo-pomaranczowy osad p-cyjanofenolu o temperaturze topnienia 89-lll°C. Osad ten przekrystalizowano z mieszaniny chloroformu i czterochlorku wegla otrzymujac 47,6 g produktu o temperaturze topnienia 111-113°C, co stanowi 80% wydajnosci teoretycz¬ nej.Zastrzezenia patentowe 1. Sposób wytwarzania p-cyjanofenolu z aldehydu p-hydroksybenzoesowego i chlorowodorku hydroksylo¬ aminy w roztworze alkoholu alifatycznego, znamienny tym, ze reakcje prowadzi sie w obecnosci 0,5—10% molowych kwasu mineralnego. 2. Sposób wedlug zastrz. 1, znamienny tym, ze jako kwas mineralny stosuje sie kwas solny. ftac PoUgnr: UF PRL naklad 120+18 Cena 45 zl PLThe present invention relates to a process for the preparation of p-cyanophenol from p-hydroxybenzaldehyde. p-Cyanophenol is used as a starting compound in the synthesis of a large group of liquid crystalline compounds which are p-cyanophenyl esters of substituted benzoic acids, especially p-alkyl or p-alkoxybenzoic. These esters are nematic liquid crystalline substances used in electro-optical devices, especially in the indicators of digital watches and electronic calculators. There is a known method of producing p-cyanophenol from p-hydroxybenzaldehyde, which is reacted with hydroxylamine, possibly in the form of a hydrochloride base, in the presence of . The product of this reaction is an oxime, which is then dehydrated by means of dehydrating agents. The traditional agent used to dehydrate oximes to nitriles is acetic anhydride. When hydroxybenzaldehyde is used as a substrate, there is the possibility of esterification which necessitates additional hydrolysis of the ester formed. This process is a multi-step process. Other dehydrating agents can also be used, for example p-toluenesulfonic acid, dicyclohexylcarbodiimide. However, a transient oxime should always be isolated and a dehydrating agent applied. N Surprisingly, it turned out that if the known reaction of p-hydroxybenzaldehyde with hydroxylamine hydrochloride is carried out in the presence of a mineral acid, the product is p-cyanophenol, and not an oxime, as is the case in known processes. -hydroxybenzoic acid with hydroxylamine hydrochloride in the environment of an aliphatic alcohol in the presence of 0.5-10 mol% of a mineral acid. The method according to the invention therefore allows for the production of p-cyanophenol without the troublesome release of oxime and its additional dehydration, which was shown above, is a significant obstacle It is also emphasized that the reaction carried out under identical conditions between hydroxylamine and aldehydes with substituents other than the hydroxyl group does not result in substituted benzonitriles but oximes of the corresponding aldehydes. This confirms the surprising effect of the process according to the invention. The yield of the pure product according to the invention is 80% with the use of technical aldehyde. After the initial purification of p-hydroxybenzaldehyde from colored oxidation products, losses in the purification of p-cyanophenol are lower and the yield can reach 90%. Hydrochloric acid is used as the mineral acid. The method according to the invention is illustrated by the following example. 50.3 g (0.05 mol) of p-hydroxybenzaldehyde, 35 g (0.05 mol) of hydroxylamine hydrochloride and 300 ml of 96% ethyl alcohol were placed in a 1 liter round bottom flask. 3 drops of concentrated hydrochloric acid were added to the solution and it was heated to reflux for 12 hours. After cooling, the solution was concentrated to form a solidifying oil. This oil was purified by crystallization from boiling water with the addition of activated carbon. A pink-orange precipitate of p-cyanophenol with a melting point of 89-11 ° C was obtained. This precipitate was recrystallized from a mixture of chloroform and carbon tetrachloride to obtain 47.6 g of product with a melting point of 111-113 ° C, which is 80% of theoretical yield. Claims 1. Method for the preparation of p-cyanophenol from p-hydroxybenzaldehyde and hydroxyl hydrochloride ¬ amine in a solution of an aliphatic alcohol, characterized in that the reactions are carried out in the presence of 0.5-10 mol% of the mineral acid. 2. The method according to claim A process as claimed in claim 1, characterized in that hydrochloric acid is used as the mineral acid. ftac PoUgnr: UF PRL edition 120 + 18 Price PLN 45 PL

Claims (2)

Zastrzezenia patentowe 1. Sposób wytwarzania p-cyjanofenolu z aldehydu p-hydroksybenzoesowego i chlorowodorku hydroksylo¬ aminy w roztworze alkoholu alifatycznego, znamienny tym, ze reakcje prowadzi sie w obecnosci 0,5—10% molowych kwasu mineralnego.Claims 1. A method for producing p-cyanophenol from p-hydroxybenzaldehyde and hydroxylamine hydrochloride in an aliphatic alcohol solution, characterized in that the reactions are carried out in the presence of 0.5-10 mol% of mineral acid. 2. Sposób wedlug zastrz. 1, znamienny tym, ze jako kwas mineralny stosuje sie kwas solny. ftac PoUgnr: UF PRL naklad 120+18 Cena 45 zl PL2. The method according to claim A process as claimed in claim 1, characterized in that hydrochloric acid is used as the mineral acid. ftac PoUgnr: UF PRL edition 120 + 18 Price PLN 45 PL
PL22060079A 1979-12-21 1979-12-21 Method of p-cyanophenol manufacture PL115568B2 (en)

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PL22060079A PL115568B2 (en) 1979-12-21 1979-12-21 Method of p-cyanophenol manufacture

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PL22060079A PL115568B2 (en) 1979-12-21 1979-12-21 Method of p-cyanophenol manufacture

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PL220600A2 PL220600A2 (en) 1980-10-20
PL115568B2 true PL115568B2 (en) 1981-04-30

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