Rosco P. Coaltrain
2004-02-05 06:17:36 UTC
A simplified method for producing azides was described
in two old British patents issued in 1919 , and this
subject became the topic for a lengthy thread in this
news group . In order to simplify readers access to
the text for the main patent GB128014 , without having
to sort through the presently eighty-six messages
in the original thread , it seems fitting to repost
that patent text as a separate topic here .
GB128014 , Complete Specification ,
Improvements in and relating to the Production of Azides
application date: June 17 , 1918 No. 9952 / 18
complete accepted : June 17 , 1919
I , William Richard Hodgkinson , C.B.E. , of Ordnance College ,
Woolwich , London , S.E. 18 , Professor of Chemistry and Metallurgy ,
do hereby declare the nature of this invention and in what manner
the same is to be performed , to be particularly described and
ascertained in and by the following statement :
This invention relates to the production of azides .
The object of the invention is to provide a process of producing
azides from salts of hydrazine without the employment of
ethyl benzoate or the like , and the formation of benzoyl hydrazine .
According to the invention , salts of hydrazine are diazotised
by means of a suitable nitrite under such conditions that the
reaction mass is at no time so distinctly acid as to redden
litmus paper , but appears on the border line of acidity and
alkalinity . The conditions of acidity under which the reaction
is carried out according to the invention , are preferably
comparable with the conditions of acidity as indicated by
litmus paper , of , for instance a solution of boric acid .
Thus in accordance with the invention , the nitrite solution
is brought together with a salt of hydrazine in approximately
the proportions required on the basis of theory to diazotise
the hydrazine , under such conditions that the acidity never
exceeds the degree of acidity indicated above , and an
acidified salt of the metal of which the azide is required ,
is introduced into the mixture , or alternatively the mixture
is added to the solution of the salt of the metal .
For example , silver azide is formed by adding a neutral solution
of hydrazine sulphate and sodium nitrite in molecular proportions
to a solution of silver nitrate of a degree of acidity with
nitric acid enabling the conditions in regard to acidity
set forth above to be realised , while avoiding the precipitation
of silver sulphate . Thus,for example 130 grams of hydrazine sulphate
is converted to the neutral hydrazine ammonium sulphate , which is
more soluble in water than is the simple hydrazine sulphate ,
by the addition of ammonia solution , the mixture being made up
to about 500 ccs . To this solution contained in a vessel in which
it can be violently agitated , the calculated amount of sodium nitrite
dissolved in 500 ccs. of water is added slowly so that the temperature
does not rise much above 30 degrees Centigrade .
The reaction resulting in the formation of sodium azide may be
represented by the following equation :
N2H4-H-NH3-H-SO4 + NaNO2 -----> NH4HSO4 + NaN3 + 2 H2O
From this equation it will be seen that the solution would
become acid as the result of the reaction were it not for
the fact that sodium nitrite is never pure but is alkaline ,
the alkali in the nitrite ordinarily being sufficient to maintain
the solution on the border line of acidity and alkalinity ,
and addition of a small quantity of alkali being made
should such not be the case . The solution thus made contains
sodium azide , some unchanged reagents , and the by-products
of the reaction .
The sodium sulphate and sodium azide contained in the solution
may be separated by crystallisation but preferably the solution
is added gradually to an acidified solution of silver nitrate
produced by adding 1.0 cc. of 70% of nitric acid to 1000 ccs.
of a normal solution of silver nitrate which is violently agitated
during such adding , the temperature of the reaction mass being
prevented from rising much higher than 30 - 40 degrees Centigrade .
With adequate cooling and agitation the yield of silver azide may
be obtained equivalent to 85 % of the calculated possible amount .
Instead of adding the diazotised solution to the acidifed
silver nitrate solution , the latter may be added to the former .
When starting from hydrazine nitrate which is also an acid salt ,
a solution of ammonia should be added in order to form the
neutral hydrazine ammonium salt or , if desired ,
the neutral hydrazine sodium salt may be produced ,
the remaining steps of the process being then carried out
as above described .
In producing lead azide , a solution of a hydrazine salt
of an acid which will not result in the precipitation
of an insoluble lead salt of the acid in question ,
for instance hydrazine nitrate , is employed , and
the reaction mass in this case should be only just acid ,
as lead azide is particularly easily acted on by acids ,
while in producing silver azide the acidity of the
reaction mass may be greater in order to avoid the precipitation
of silver sulphate and agitation indicated in the foregoing example .
The azides produced in accordance with the invention are
usually amorphous , and in this state they are safer to handle
than when crystalline .
Having now particularly described and ascertained the nature
of my said invention and in what manner the same is to be performed ,
I declare that what I claim is :
1. The process of producing azides from salts of hydrazine
in which salts of hydrazine are diazotised by means of a
suitable nitrite under such conditions that the reaction mass
is at no time so distinctly acid as to redden litmus paper ,
but appears on the border line of acidity and alkalinity .
2. The process as claimed in Claim 1 in which the conditions
of acidity under which the reaction is carried out according
to the invention are preferably comparable with conditions
of acidity as indicated by litmus paper , of , for instance ,
a solution of boric acid .
3. The process of producing azides from salts of hydrazine ,
substantially as hereinbefore described .
Dated this 10th day of December , 1918
in two old British patents issued in 1919 , and this
subject became the topic for a lengthy thread in this
news group . In order to simplify readers access to
the text for the main patent GB128014 , without having
to sort through the presently eighty-six messages
in the original thread , it seems fitting to repost
that patent text as a separate topic here .
GB128014 , Complete Specification ,
Improvements in and relating to the Production of Azides
application date: June 17 , 1918 No. 9952 / 18
complete accepted : June 17 , 1919
I , William Richard Hodgkinson , C.B.E. , of Ordnance College ,
Woolwich , London , S.E. 18 , Professor of Chemistry and Metallurgy ,
do hereby declare the nature of this invention and in what manner
the same is to be performed , to be particularly described and
ascertained in and by the following statement :
This invention relates to the production of azides .
The object of the invention is to provide a process of producing
azides from salts of hydrazine without the employment of
ethyl benzoate or the like , and the formation of benzoyl hydrazine .
According to the invention , salts of hydrazine are diazotised
by means of a suitable nitrite under such conditions that the
reaction mass is at no time so distinctly acid as to redden
litmus paper , but appears on the border line of acidity and
alkalinity . The conditions of acidity under which the reaction
is carried out according to the invention , are preferably
comparable with the conditions of acidity as indicated by
litmus paper , of , for instance a solution of boric acid .
Thus in accordance with the invention , the nitrite solution
is brought together with a salt of hydrazine in approximately
the proportions required on the basis of theory to diazotise
the hydrazine , under such conditions that the acidity never
exceeds the degree of acidity indicated above , and an
acidified salt of the metal of which the azide is required ,
is introduced into the mixture , or alternatively the mixture
is added to the solution of the salt of the metal .
For example , silver azide is formed by adding a neutral solution
of hydrazine sulphate and sodium nitrite in molecular proportions
to a solution of silver nitrate of a degree of acidity with
nitric acid enabling the conditions in regard to acidity
set forth above to be realised , while avoiding the precipitation
of silver sulphate . Thus,for example 130 grams of hydrazine sulphate
is converted to the neutral hydrazine ammonium sulphate , which is
more soluble in water than is the simple hydrazine sulphate ,
by the addition of ammonia solution , the mixture being made up
to about 500 ccs . To this solution contained in a vessel in which
it can be violently agitated , the calculated amount of sodium nitrite
dissolved in 500 ccs. of water is added slowly so that the temperature
does not rise much above 30 degrees Centigrade .
The reaction resulting in the formation of sodium azide may be
represented by the following equation :
N2H4-H-NH3-H-SO4 + NaNO2 -----> NH4HSO4 + NaN3 + 2 H2O
From this equation it will be seen that the solution would
become acid as the result of the reaction were it not for
the fact that sodium nitrite is never pure but is alkaline ,
the alkali in the nitrite ordinarily being sufficient to maintain
the solution on the border line of acidity and alkalinity ,
and addition of a small quantity of alkali being made
should such not be the case . The solution thus made contains
sodium azide , some unchanged reagents , and the by-products
of the reaction .
The sodium sulphate and sodium azide contained in the solution
may be separated by crystallisation but preferably the solution
is added gradually to an acidified solution of silver nitrate
produced by adding 1.0 cc. of 70% of nitric acid to 1000 ccs.
of a normal solution of silver nitrate which is violently agitated
during such adding , the temperature of the reaction mass being
prevented from rising much higher than 30 - 40 degrees Centigrade .
With adequate cooling and agitation the yield of silver azide may
be obtained equivalent to 85 % of the calculated possible amount .
Instead of adding the diazotised solution to the acidifed
silver nitrate solution , the latter may be added to the former .
When starting from hydrazine nitrate which is also an acid salt ,
a solution of ammonia should be added in order to form the
neutral hydrazine ammonium salt or , if desired ,
the neutral hydrazine sodium salt may be produced ,
the remaining steps of the process being then carried out
as above described .
In producing lead azide , a solution of a hydrazine salt
of an acid which will not result in the precipitation
of an insoluble lead salt of the acid in question ,
for instance hydrazine nitrate , is employed , and
the reaction mass in this case should be only just acid ,
as lead azide is particularly easily acted on by acids ,
while in producing silver azide the acidity of the
reaction mass may be greater in order to avoid the precipitation
of silver sulphate and agitation indicated in the foregoing example .
The azides produced in accordance with the invention are
usually amorphous , and in this state they are safer to handle
than when crystalline .
Having now particularly described and ascertained the nature
of my said invention and in what manner the same is to be performed ,
I declare that what I claim is :
1. The process of producing azides from salts of hydrazine
in which salts of hydrazine are diazotised by means of a
suitable nitrite under such conditions that the reaction mass
is at no time so distinctly acid as to redden litmus paper ,
but appears on the border line of acidity and alkalinity .
2. The process as claimed in Claim 1 in which the conditions
of acidity under which the reaction is carried out according
to the invention are preferably comparable with conditions
of acidity as indicated by litmus paper , of , for instance ,
a solution of boric acid .
3. The process of producing azides from salts of hydrazine ,
substantially as hereinbefore described .
Dated this 10th day of December , 1918