How to create custom parser to get entities in given Text using ChemDataExtractor?

Can anyone share me how to write custom parser to fetch Chemical molecule name with constituents details in desired format

[Chemical name + addition : Constituents]

doc = Paragraph('4-Methylmorpholine N-oxide (1.76 mL, 8.42 mmol) and potassium osmate dihydrate (97.3 mg, 0.38 mmol) ')

This is my code:

class BoilingPoint(BaseModel):
 name=StringType()
 Quan = StringType()
 units =StringType()

Compound.addition = ListType(ModelType(BoilingPoint))

import re
from chemdataextractor.parse import R, I, W, Optional, merge

units = R('^(mg|mL|mmol)$')(u'units').add_action(merge)  # Define all units in parser
Quan = R(u'^\d+(\.\d+)?$')(u'value')
bp = (Quan+ units)(u'mL')


from chemdataextractor.parse.base import BaseParser
from chemdataextractor.utils import first

class BpParser(BaseParser):
   root=bp

 def interpret(self, result, start, end):
    compound = Compound(
        addition=[BoilingPoint(

                #name=first(result.xpath('./name/text()'))
                Quan=first(result.xpath('./value/text()')),
                units=first(result.xpath('./units/text()'))


            )
        ]
     )
    yield compound

Paragraph.parsers = [CompoundParser()]+[BpParser()]

Result: [{'names': ['4-Methylmorpholine N-oxide']}, {'names': ['potassium osmate dihydrate']}, {'addition': [{'Quan': '1.76', 'units': 'mL'}]}, {'addition': [{'Quan': '8.42', 'units': 'mmol'}]}, {'addition': [{'Quan': '97.3', 'units': 'mg'}]}, {'addition': [{'Quan': '0.38', 'units': 'mmol'}]}]

Expected Result: Chemical name + addition : Constituents

[{'names': ['4-Methylmorpholine N-oxide'],'addition': [{'Quan': '1.76', 'units': 'mL'}]},{'Quan': '8.42', 'units': 'mmol'}}]