If there is alcohol used to create vinegar such as red wine if it is converted into vinegar and sold as red wine vinegar is it halal or does it remain haram
If it has completely converted such that drinking it will not cause intoxication, no matter how much you drink, then it is tahir and halal, it is permissible to consume it and sell it. The following hadith of the Prophet ﷺ evidences its permissibility of vinegar in general:
نعم الأدم الخل
Vinegar is an excellent condiment
Note that it is agreed upon that the above applies if the conversion has occurred naturally, without any intent from a human. However there is difference among the schools on the status of vinegar that is purposefully made from wine by human actions.
The view of the majority is that such vinegar is haram, based on the following hadith:
أن أبا طلحة، سأل النبي صلى الله عليه وسلم عن أيتام ورثوا خمرا قال أهرقها . قال أفلا أجعلها خلا قال لا
Abu Talhah asked the Prophet (ﷺ) about the orphans who had inherited wine. He replied: Pour it out. He asked: May I not make vinegar of it ? He replied : No.
In the following I'd like to add some additional details and additions to the great answer of @UmH:
When it comes to vinegar we know that it is a product that has formally been or converted to alcohol.
However in some hanabli fiqh books there's a description of procedure to get vinegar which doesn't need alcohol and which is considered as permissible:
It says in al-Insaaf by al-Mirdaawi (1/320): Permissible vinegar is made by adding vinegar to the grapes or to the juice before they ferment, so that they will not ferment. This was stated by a number of scholars. End quote.
In Mataalib Ooli an-Nuha (1/230) it says: Permissible vinegar is made by adding vinegar to the grapes or to the juice before they ferment, before three days and nights have past, so that they will not ferment. This was narrated by a number of scholars from Ahmad. End quote. (Source of both quotes: islamqa #191176)
By default using vinegar is permissible, but one must be aware of some specifications and restrictions:
Case 1: vinegar that results from a natural process
Among Muslim scholars there's no discussion about the permission to use vinegar that has converted naturally from alcohol without any human influence be it addition of Enzyms, vinegar, salt or heating the alcohol etc.. Based on the statement
Allah's Messenger (ﷺ) took hold of my hand one day (and led me) to his residence. There was presented to him some pieces of bread, whereupon he said: Is there no condiment? They (the members of his household) said: No, except some vinegar. He (the Holy Prophet) said: Vinegar is a good condiment. Jabir said: I have always loved vinegar since I heard it trom Allah's Apostle (ﷺ). Talha said: I have always loved vinegar since I heard about it from Jabir. (Sahih Muslim)
But to reach this permission this vinegar must no more include alcohol (or maybe an amount of alcohol) that causes intoxication due to the known hadith:
Every intoxicant is Khamr and every intoxicant is forbidden. (See for example in Sahih Muslim)
and therefore such a vinegar is considered as Najis (containing alcohol) and therefor as not permissible.
Case2: vinegar that is produced by subjecting it to a deliberate process
In the case if the alcohol converted to vinegar by human influence there's a difference of opinion based on ahadith and their interpretation.
It is considered as haram by the shafi'i school of jurisprudence and the hanbali school of jurisprudence and one statement of imam Malik.
Some evidences for that can be found in the sunnah:
Allah's Messenger (ﷺ) was asked about the use of Khamr from which vinegar is prepared. He said: No (it is prohibited). (Sahih Muslim)
Abu Talhah asked the prophet (ﷺ) about the orphans who had inherited wine. He replied: Pour it out. He asked: May I not make vinegar of it ? He replied : No. (Sunan abi Dawod and Musnad Ahmad)
While the hanafi school of jurisprudence and the stronger view in the maliki school of jurisprudence is that it is permissible as the statement of the hadith above:
Vinegar is a good condiment
is general terms and doesn't differentiate the process of production of the vinegar. Furthermore this deliberate process actually has many benefits that make it a reason to declare it permissible by analogy:
That is also because subjecting wine to a deliberate process to turn it into vinegar removes the evil characteristics [of wine] whilst leaving the good characteristics, because it contains some characteristics that are beneficial for medicinal and nutritional purposes, and other purposes. If the corrupt element which dictates the prohibition of wine is removed, it becomes halaal, just as in the case when it turns into vinegar by itself.
That is because subjecting wine to a deliberate process to turn it into vinegar is rectifying its character, therefore it becomes permissible, by analogy with the permissibility of tanning animal hides.
Al-Mawsoo‘ah al-Fiqhiyyah (19/260). (Source: islamqa #276185)
Summary from of the scholarly views
Imam an-Nawawi made a good summary of the scholarly views on the cases described above in his al-Majmo' المجموع -see here in Arabic-:
In the following I'm translating from Arabic language, most of the text is taken from the fatwa linked above nevertheless it is partly my own translatzion so take it with the necessary care!
في مذاهب العلماء في تخلل الخمر وتخليلها .
According to the scholarly views concerning wine that turns into vinegar by itself and subjecting wine to a deliberate process to turn it into vinegar
أما إذا انقلبت بنفسها خلا فتطهر عند جمهور العلماء ونقل القاضي عبد الوهاب المالكي فيه الإجماع وحكى غيره عن سحنون المالكي أنها لا تطهر ،
if it turns into vinegar by itself, then it becomes pure (taahir), according to the majority of scholars. al-Qaadi ‘Abd al-Wahhaab al-Maaliki narrated that there was consensus on that; others narrated from Sahnoon al-Maaliki that it does not become pure.
وأما إذا خللت بوضع شيء فيها فمذهبنا أنها لا تطهر وبه قال أحمد والأكثرون .
But if it turns into vinegar as the result of adding something to it, then our view is that it does not become pure. This was the view of Ahmad and the majority.
وقال أبو حنيفة والأوزاعي والليث : تطهر ،
Abu Haneefah, al-Awzaa‘i and al-Layth said: It does become pure.
وعن مالك ثلاث روايات أصحها عنه أن التخليل حرام [ وتطهر ] فلو خللها طهرت والثانية حرام ولا تطهر والثالثة : حلال وتطهر
Three reports were narrated from Maalik. That which is most soundly narrated from him says that subjecting wine to a deliberate process to turn it into vinegar is haraam, but if it turns into vinegar by itself, it becomes pure. The second view is that it is haraam and does not become pure. The third view is that it is halaal and does become pure.
دليلنا ما سبق . And our evidence is what was quoted earlier (1)
(1): reference to the hadith of Abu Talhah
He also used the above evidences to show that the vinegar from a deliberate process is Najis and can't become tahir in opposition to the view of the hanafis which is described above. He also pointed at the difference of opinion on vinegar that has converted by moving the alcohol from sunlight into shadow and vice versa and held the opinion that the resulting vinegar according to his view is tahir.
What about vinegar that has been produced by non-Muslims?
As for the vinegar produced by ahl-al-Kitab scholars consider it as permissible as they consider wine as permissible (and tahir):
Others said that if it was turned into vinegar by one who believes that wine is permissible, such as the People of the Book, the Jews and Christians, it is permissible and has become pure. But if it is turned into vinegar by someone for whom it is not permissible, then it is haraam and impure. This is the view that is most likely to be correct.
Based on that, the vinegar that comes from the Jews and Christians is halaal and pure, because they did that on the basis of their belief that it is permissible, hence they are not to be prevented from drinking wine.
End quote from ash-Sharh al-Mumti‘ (1/432). (Source islamqa #276185)
See also: Why is this hadith stated this way?.